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2015 |
Sara Spotorno; George L. Malcolm; Benjamin W. Tatler Disentangling the effects of spatial inconsistency of targets and distractors when searching in realistic scenes Journal Article In: Journal of Vision, vol. 15, no. 2, pp. 1–21, 2015. @article{Spotorno2015, Previous research has suggested that correctly placed objects facilitate eye guidance, but also that objects violating spatial associations within scenes may be prioritized for selection and subsequent inspection. We analyzed the respective eye guidance of spatial expectations and target template (precise picture or verbal label) in visual search, while taking into account any impact of object spatial inconsistency on extrafoveal or foveal processing. Moreover, we isolated search disruption due to misleading spatial expectations about the target from the influence of spatial inconsistency within the scene upon search behavior. Reliable spatial expectations and precise target template improved oculomotor efficiency across all search phases. Spatial inconsistency resulted in preferential saccadic selection when guidance by template was insufficient to ensure effective search from the outset and the misplaced object was bigger than the objects consistently placed in the same scene region. This prioritization emerged principally during early inspection of the region, but the inconsistent object also tended to be preferentially fixated overall across region viewing. These results suggest that objects are first selected covertly on the basis of their relative size and that subsequent overt selection is made considering object-context associations processed in extrafoveal vision. Once the object was fixated, inconsistency resulted in longer first fixation duration and longer total dwell time. As a whole, our findings indicate that observed impairment of oculomotor behavior when searching for an implausibly placed target is the combined product of disruption due to unreliable spatial expectations and prioritization of inconsistent objects before and during object fixation. |
William W. Sprague; Emily A. Cooper; Ivana Tošić; Martin S. Banks Stereopsis is adaptive for the natural environment Journal Article In: Science Advances, vol. 1, pp. e1400254, 2015. @article{Sprague2015, Humans and many animals have forward-facing eyes providing different views of the environment. Precise depth estimates can be derived from the resulting binocular disparities, but determining which parts of the two retinal images correspond to one another is computationally challenging. To aid the computation, the visual system focuses the search on a small range of disparities. We asked whether the disparities encountered in the natural environment match that range. We did this by simultaneously measuring binocular eye position and three-dimensional scene geometry during natural tasks. The natural distribution of disparities is indeed matched to the smaller range of correspondence search. Furthermore, the distribution explains the perception of some ambiguous stereograms. Finally, disparity preferences of macaque cortical neurons are consistent with the natural distribution. |
Beth A. Stankevich; Joy J. Geng The modulation of reward priority by top-down knowledge Journal Article In: Visual Cognition, vol. 23, no. 1-2, pp. 206–228, 2015. @article{Stankevich2015, Reward-associated features capture attention automatically and continue to do so even when the reward contingencies are removed. This profile has led to the hypothesis that rewards belong to a separate class of attentional biases that is neither typically top-down nor bottom-up. The goal of these experiments was to understand the degree to which top-down knowledge can modulate value-driven attentional capture within (a) the timecourse of a single trial and (b) when the reward contingencies change explicitly over trials. The results suggested that top-down knowledge does not affect the size of value-driven attentional capture within a single trial. There were clear top-down modulations in the magnitude of value-driven capture when reward contingencies explicitly changed, but the original reward associations continued to have a persistent bias on attention. These results contribute to a growing body of evidence that reward associations bias attention through mechanisms separate from other top-down and bottom-up attentional biases. |
Supriya Ray; Stephen J. Heinen A mechanism for decision rule discrimination by supplementary eye field neurons Journal Article In: Experimental Brain Research, vol. 233, no. 2, pp. 459–476, 2015. @article{Ray2015, A decision to select an action from alternatives is often guided by rules that flexibly map sensory inputs to motor outputs when certain conditions are satisfied. However, the neural mechanisms underlying rule-based decision making remain poorly understood. Two complementary types of neurons in the supplementary eye field (SEF) of macaques have been identified that modulate activity differentially to interpret rules in an ocular go–nogo task, which stipulates that the animal either visually pursue a moving object if it intersects a visible zone (‘go'), or maintain fixation if it does not (‘nogo'). These neurons discriminate between go and nogo rule-states by increasing activity to signal their preferred (agonist) rule-state and decreasing activity to signal their non-preferred (antagonist) rule-state. In the current study, we found that SEF neurons decrease activity in anticipation of the antagonist rule-state, and do so more rapidly when the rule-state is easier to predict. This rapid decrease in activity could underlie a process of elimination in which trajectories that do not invoke the preferred rule-state receive no further computational resources. Furthermore, discrimination between difficult and easy trials in the antagonist rule-state occurs prior to when discrimination within the agonist rule-state occurs. A winner-take-all like model that incorporates a pair of mutually inhibited integrators to accumulate evidence in favor of either the decision to pursue or the decision to continue fixation accounts for the observed neural phenomena. |
Eric A. Reavis; Sebastian M. Frank; Peter U. Tse Caudate nucleus reactivity predicts perceptual learning rate for visual feature conjunctions Journal Article In: NeuroImage, vol. 110, pp. 171–181, 2015. @article{Reavis2015, Useful information in the visual environment is often contained in specific conjunctions of visual features (e.g., color and shape). The ability to quickly and accurately process such conjunctions can be learned. However, the neural mechanisms responsible for such learning remain largely unknown. It has been suggested that some forms of visual learning might involve the dopaminergic neuromodulatory system (Roelfsema et al., 2010; Seitz and Watanabe, 2005), but this hypothesis has not yet been directly tested. Here we test the hypothesis that learning visual feature conjunctions involves the dopaminergic system, using functional neuroimaging, genetic assays, and behavioral testing techniques. We use a correlative approach to evaluate potential associations between individual differences in visual feature conjunction learning rate and individual differences in dopaminergic function as indexed by neuroimaging and genetic markers. We find a significant correlation between activity in the caudate nucleus (a component of the dopaminergic system connected to visual areas of the brain) and visual feature conjunction learning rate. Specifically, individuals who showed a larger difference in activity between positive and negative feedback on an unrelated cognitive task, indicative of a more reactive dopaminergic system, learned visual feature conjunctions more quickly than those who showed a smaller activity difference. This finding supports the hypothesis that the dopaminergic system is involved in visual learning, and suggests that visual feature conjunction learning could be closely related to associative learning. However, no significant, reliable correlations were found between feature conjunction learning and genotype or dopaminergic activity in any other regions of interest. |
Alexandra Reichenbach; Jörn Diedrichsen Processing reafferent and exafferent visual information for action and perception Journal Article In: Journal of Vision, vol. 15, no. 8, pp. 1–12, 2015. @article{Reichenbach2015, A recent study suggests that reafferent hand-related visual information utilizes a privileged, attention-independent processing channel for motor control. This process was termed visuomotor binding to reflect its proposed function: linking visual reafferences to the corresponding motor control centers. Here, we ask whether the advantage of processing reafferent over exafferent visual information is a specific feature of the motor processing stream or whether the improved processing also benefits the perceptual processing stream. Human participants performed a bimanual reaching task in a cluttered visual display, and one of the visual hand cursors could be displaced laterally during the movement. We measured the rapid feedback responses of the motor system as well as matched perceptual judgments of which cursor was displaced. Perceptual judgments were either made by watching the visual scene without moving or made simultaneously to the reaching tasks, such that the perceptual processing stream could also profit from the specialized processing of reafferent information in the latter case. Our results demonstrate that perceptual judgments in the heavily cluttered visual environment were improved when performed based on reafferent information. Even in this case, however, the filtering capability of the perceptual processing stream suffered more from the increasing complexity of the visual scene than the motor processing stream. These findings suggest partly shared and partly segregated processing of reafferent information for vision for motor control versus vision for perception. |
Regina M. Reinert; Stefan Huber; Hans-Christoph Nuerk; Korbinian Moeller Strategies in unbounded number line estimation? Evidence from eye-tracking Journal Article In: Cognitive Processing, vol. 16, no. 1, pp. 359–363, 2015. @article{Reinert2015, For bounded number line estimation, recent studies indicated influences of proportion-based strategies as documented by eye-tracking data. In the current study, we investigated solution strategies in bounded and unbounded number line estimation by directly comparing participants' estimation performance as well as their corresponding eye-fixation behaviour. For bounded number line estimation, increased numbers of fixations at and around reference points (i.e. start, middle and endpoint) confirmed the prominent use of proportion-based strategies. In contrast, in unbounded number line estimation, the number of fixations on the number line decreased continuously with increasing magnitude of the target number. Additionally, we observed that in bounded and unbounded number line estimation participants' first fixation on the number line was a valid predictor of the location of the target number. In sum, these data corroborate the idea that unbounded number line estimation is less influenced by proportion-based estimation strategies not directly related to numerical estimations. |
James D. Retell; Dustin Venini; Stefanie I. Becker Oculomotor capture by new and unannounced color singletons during visual search Journal Article In: Attention, Perception, and Psychophysics, vol. 77, pp. 1529–1543, 2015. @article{Retell2015, The surprise capture hypothesis states that a stimulus will capture attention to the extent that it is preattentively available and deviates from task-expectancies. Interestingly, it has been noted by Horstmann (Psychological Science 13: 499–505. doi:10.1111/1467-9280.00488, 2002, Human Perception and Performance 31: 1039–1060. doi:10.1037/ 00961523.31.5.1039, 2005, Psychological Research, 70, 13- 25, 2006) that the time course of capture by such classes of stimuli appears distinct from that of capture by expected stimuli. Specifically, attention shifts to an unexpected stimulus are delayed relative to an expected stimulus (delayed onset account). Across two experiments, we investigated this claim under conditions of unguided (Exp. 1) and guided (Exp. 2) search using eye-movements as the primary index of attentional selection. In both experiments, we found strong evidence of surprise capture for the first presentation of an unannounced color singleton. However, in both experiments the pattern of eye-movements was not consistent with a delayed onset account of attention capture. Rather, we observed costs associated with the unexpected stimulus only once the target had been selected. We propose an interference account of surprise capture to explain our data and argue that this account also can explain existing patterns of data in the literature. |
Michael R. Richards; Henry W. Fields; F. Michael Beck; Allen R. Firestone; Dirk B. Walther; Stephen F. Rosenstiel; James M. Sacksteder Contribution of malocclusion and female facial attractiveness to smile esthetics evaluated by eye tracking Journal Article In: American Journal of Orthodontics and Dentofacial Orthopedics, vol. 147, no. 4, pp. 472–482, 2015. @article{Richards2015, There is disagreement in the literature concerning the importance of the mouth in overall facial attractiveness. Eye tracking provides an objective method to evaluate what people see. The objective of this study was to determine whether dental and facial attractiveness alters viewers' visual attention in terms of which area of the face (eyes, nose, mouth, chin, ears, or other) is viewed first, viewed the greatest number of times, and viewed for the greatest total time (duration) using eye tracking. Methods Seventy-six viewers underwent 1 eye tracking session. Of these, 53 were white (49% female, 51% male). Their ages ranged from 18 to 29 years, with a mean of 19.8 years, and none were dental professionals. After being positioned and calibrated, they were shown 24 unique female composite images, each image shown twice for reliability. These images reflected a repaired unilateral cleft lip or 3 grades of dental attractiveness similar to those of grades 1 (near ideal), 7 (borderline treatment need), and 10 (definite treatment need) as assessed in the aesthetic component of the Index of Orthodontic Treatment Need (AC-IOTN). The images were then embedded in faces of 3 levels of attractiveness: attractive, average, and unattractive. During viewing, data were collected for the first location, frequency, and duration of each viewer's gaze. Results Observer reliability ranged from 0.58 to 0.92 (intraclass correlation coefficients) but was less than 0.07 (interrater) for the chin, which was eliminated from the study. Likewise, reliability for the area of first fixation was kappa less than 0.10 for both intrarater and interrater reliabilities; the area of first fixation was also removed from the data analysis. Repeated-measures analysis of variance showed a significant effect (P <0.001) for level of attractiveness by malocclusion by area of the face. For both number of fixations and duration of fixations, the eyes overwhelmingly were most salient, with the mouth receiving the second most visual attention. At times, the mouth and the eyes were statistically indistinguishable in viewers' gazes of fixation and duration. As the dental attractiveness decreased, the visual attention increased on the mouth, approaching that of the eyes. AC-IOTN grade 10 gained the most attention, followed by both AC-IOTN grade 7 and the cleft. AC-IOTN grade 1 received the least amount of visual attention. Also, lower dental attractiveness (AC-IOTN 7 and AC-IOTN 10) received more visual attention as facial attractiveness increased. Conclusions Eye tracking indicates that dental attractiveness can alter the level of visual attention depending on the female models' facial attractiveness when viewed by laypersons. |
Gerulf Rieger; Brian M. Cash; Sarah M. Merrill; James Jones-Rounds; Sanjay Muralidharan Dharmavaram; Ritch C. Savin-Williams Sexual arousal: The correspondence of eyes and genitals Journal Article In: Biological Psychology, vol. 104, pp. 56–64, 2015. @article{Rieger2015, Men's, more than women's, sexual responses may include a coordination of several physiological indices in order to build their sexual arousal to relevant targets. Here, for the first time, genital arousal and pupil dilation to sexual stimuli were simultaneously assessed. These measures corresponded more strongly with each other, subjective sexual arousal, and self-reported sexual orientation in men than women. Bisexual arousal is more prevalent in women than men. We therefore predicted that if bisexual-identified men show bisexual arousal, the correspondence of their arousal indices would be more female-typical, thus weaker, than for other men. Homosexual women show more male-typical arousal than other women; hence, their correspondence of arousal indices should be stronger than for other women. Findings, albeit weak in effect, supported these predictions. Thus, if sex-specific patterns are reversed within one sex, they might affect more than one aspect of sexual arousal. Because pupillary responses reflected sexual orientation similar to genital responses, they offer a less invasive alternative for the measurement of sexual arousal. |
Arryn Robbins; Michael C. Hout Categorical target templates: Typical category members are found and identified quickly during word-cued search Journal Article In: Visual Cognition, vol. 23, no. 7, pp. 817–821, 2015. @article{Robbins2015, What information do people use to guide search when they lack precise details about the appearance of their target? In this study, we employed categorical (word-cued) search and eye tracking, to examine how category typicality influences search performance. We found that typical category members were fixated and identified more quickly than atypical categories. This finding held when the participant was cued at the superordinate level (finding “clothing” among non-clothing items) or the basic level (finding a “shirt” among other clothing items). This suggests that categorical target templates may be constructed by piecing together features from the most typical category member(s). |
Joanne S. Robertson; Jason D. Forte; Michael E. R. Nicholls Deviating to the right: Using eyetracking to study the role of attention in navigation asymmetries Journal Article In: Attention, Perception, and Psychophysics, vol. 77, no. 3, pp. 830–843, 2015. @article{Robertson2015, The ability to navigate accurately through the environment and avoid obstacles is essential for effective interactions with the environment. It is therefore surprising that systematic rightward errors are observed when neurologically intact participants navigate through doorways-most likely due to the operation of biases in spatial attention. These rightward errors may arise due to the operation of an extinction-like process, whereby participants overattend to the left doorpost and collide with the right one. Alternatively, rightward biases might reflect a bisection bias, such that the extrapersonal nature of the aperture causes participants to misbisect the aperture slightly to the right of true center. Because eye movements and spatial attention are closely related, in this study we used eyetracking to test the extinction and bisection models in a remote wheelchair navigation task. University students (n = 16) made rightward errors when navigating the wheelchair through a doorway, and fixated more frequently toward the right side of the aperture throughout the trial. These results are inconsistent with an extinction-based theory of navigation asymmetry, which predicts a leftward bias in eye position due to participants overattending to the left side of the doorway. Instead, the observed rightward bias in eye movements strongly supports a bisection-based theory of navigation asymmetry, whereby participants mentally "mark" the midpoint of a doorway toward the right and then head toward that point, resulting in rightward deviations. The rightward nature of participants' navigation errors and eye positions is consistent with the existence of a rightward attentional bias for extrapersonal stimuli. |
Eefje W. M. Rondeel; Henk Steenbergen; Rob W. Holland; Ad Knippenberg A closer look at cognitive control: differences in resource allocation during updating, inhibition and switching as revealed by pupillometry Journal Article In: Frontiers in Human Neuroscience, vol. 9, pp. 494, 2015. @article{Rondeel2015, The present study investigated resource allocation, as measured by pupil dilation, in tasks measuring updating (2-Back task), inhibition (Stroop task) and switching (Number Switch task). Because each cognitive control component has unique characteristics, differences in patterns of resource allocation were expected. Pupil and behavioral data from 35 participants were analyzed. In the 2-Back task (requiring correct matching of current stimulus identity at trial p with the stimulus two trials back, p -2) we found that better performance (low total of errors made in the task) was positively correlated to the mean pupil dilation during correctly responding to targets. In the Stroop task, pupil dilation on incongruent trials was higher than those on congruent trials. Incongruent vs. congruent trial pupil dilation differences were positively related to reaction time differences between incongruent and congruent trials. Furthermore, on congruent Stroop trials, pupil dilation was negatively related to reaction times, presumably because more effort allocation paid off in terms of faster responses. In addition, pupil dilation on correctly-responded-to congruent trials predicted a weaker Stroop interference effect in terms of errors, probably because pupil dilation on congruent trials were diagnostic of task motivation, resulting in better performance. In the Number Switch task we found higher pupil dilation in switch as compared to non-switch trials. On the Number Switch task, pupil dilation was not related to performance. We also explored error-related pupil dilation in all tasks. The results provide new insights in the diversity of the cognitive control components in terms of resource allocation as a function of individual differences, task difficulty and error processing. |
Tao He; Yun Ding; Zhiguo Wang Environment- and eye-centered inhibitory cueing effects are both observed after a methodological confound is eliminated Journal Article In: Scientific Reports, vol. 5, pp. 16586, 2015. @article{He2015, Inhibition of return (IOR), typically explored in cueing paradigms, is a performance cost associated with previously attended locations and has been suggested as a crucial attentional mechanism that biases orientation towards novelty. In their seminal IOR paper, Posner and Cohen (1984) showed that IOR is coded in spatiotopic or environment-centered coordinates. Recent studies, however, have consistently reported IOR effects in both spatiotopic and retinotopic (eye-centered) coordinates. One overlooked methodological confound of all previous studies is that the spatial gradient of IOR is not considered when selecting the baseline for estimating IOR effects. This methodological issue makes it difficult to tell if the IOR effects reported in previous studies were coded in retinotopic or spatiotopic coordinates, or in both. The present study addresses this issue with the incorporation of no-cue trials to a modified cueing paradigm in which the cue and target are always intervened by a gaze-shift. The results revealed that a) IOR is indeed coded in both spatiotopic and retinotopic coordinates, and b) the methodology of previous work may have underestimated spatiotopic and retinotopic IOR effects. |
Wei He; Jon Brock; Blake W. Johnson Face processing in the brains of pre-school aged children measured with MEG Journal Article In: NeuroImage, vol. 106, pp. 317–327, 2015. @article{He2015a, There are two competing theories concerning the development of face perception: a late maturation account and an early maturation account. Magnetoencephalography (MEG) neuroimaging holds promise for adjudicating between the two opposing accounts by providing objective neurophysiological measures of face processing, with sufficient temporal resolution to isolate face-specific brain responses from those associated with other sensory, cognitive and motor processes. The current study used a customized child MEG system to measure M100 and M170 brain responses in 15 children aged three to six years while they viewed faces, cars and their phase-scrambled counterparts. Compared to adults tested using the same stimuli in a conventional MEG system, children showed significantly larger and later M100 responses. Children's M170 responses, derived by subtracting the responses to phase-scrambled images from the corresponding images (faces or cars) were delayed in latency but otherwise resembled the adult M170. This component has not been obtained in previous studies of young children tested using conventional adult MEG systems. However children did show a markedly reduced M170 response to cars in comparison to adults. This may reflect children's lack of expertise with cars relative to faces. Taken together, these data are in accord with recent behavioural and neuroimaging data that support early maturation of the basic face processing functions. |
Wei He; Marta I. Garrido; Paul F. Sowman; Jon Brock; Blake W. Johnson Development of effective connectivity in the core network for face perception Journal Article In: Human Brain Mapping, vol. 36, no. 6, pp. 2161–2173, 2015. @article{He2015b, This study measured effective connectivity within the core face network in young children using a paediatric magnetoencephalograph (MEG). Dynamic casual modeling (DCM) of brain responses was performed in a group of adults (N = 14) and a group of young children aged from 3 to 6 years (N = 15). Three candidate DCM models were tested, and the fits of the MEG data to the three models were compared at both individual and group levels. The results show that the connectivity structure of the core face network differs significantly between adults and children. Further, the relative strengths of face network connections were differentially modulated by experimental conditions in the two groups. These results support the interpretation that the core face network undergoes significant structural configuration and functional specialization between four years of age and adulthood. |
John M. Henderson; Wonil Choi Neural correlates of fixation duration during real-world scene viewing: Evidence from fixation-related (FIRE) fMRI Journal Article In: Journal of Cognitive Neuroscience, vol. 27, no. 6, pp. 1137–1145, 2015. @article{Henderson2015, During active scene perception, our eyes move from one location to another via saccadic eye movements, with the eyes fixating objects and scene elements for varying amounts of time. Much of the variability in fixation duration is accounted for by attentional, perceptual, and cognitive processes associated with scene analysis and comprehension. For this reason, current theories of active scene viewing attempt to account for the influence of attention and cognition on fixation duration. Yet almost nothing is known about the neurocognitive systems associated with variation in fixation duration during scene viewing. We addressed this topic using fixation-related fMRI, which involves coregistering high-resolution eye tracking and magnetic resonance scanning to conduct event-related fMRI analysis based on characteristics of eye movements. We observed that activation in visual and prefrontal executive control areas was positively correlated with fixation duration, whereas activation in ventral areas associated with scene en- coding and medial superior frontal and paracentral regions associated with changing action plans was negatively correlated with fixation duration. The results suggest that fixation duration in scene viewing is controlled by cognitive processes associated with real-time scene analysis interacting with motor planning, consistent with current computational models of active vision for scene perception. |
Frouke Hermens Fixation instruction influences gaze cueing Journal Article In: Visual Cognition, vol. 23, no. 4, pp. 432–449, 2015. @article{Hermens2015a, Studies have shown that perceiving another person's gaze shift facilitates responses in the direction of the perceived gaze shift. While it is often assumed that participants in these experiments remain fixated on the cue in the cueing interval, eye gaze is not always recorded to confirm this. The data presented here suggest that the effect of gaze cues on responses to peripheral targets depends on whether participants make eye movements prior to the onset of the target. Participants who were required to fixate showed cueing effects at short cue-target intervals, but no cueing at later intervals. Participants who could look around, often chose to do so, and showed the same positive cueing effects at the shorter interval, but negative cueing effects (suggestive of inhibition of return) at the longer interval. |
Arvid Herwig; Katharina Weiß; Werner X. Schneider When circles become triangular: How transsaccadic predictions shape the perception of shape Journal Article In: Annals of the New York Academy of Sciences, vol. 1339, no. 1, pp. 97–105, 2015. @article{Herwig2015, Human vision is characterized by a consistent pattern of saccadic eye movements. With each saccade, internal object representations change their retinal position and spatial resolution. This raises the question as to how peripheral perception is affected by imminent saccadic eye movements. Here, we suggest that saccades are accompanied by a prediction of their perceptual consequences (i.e., the foveation of the target object). Accordingly, peripheral perception should be biased toward previously associated foveal input. In this study, we first exposed participants to an altered visual stimulation where one object systematically changed its shape during saccades. Subsequently, participants had to judge the shape of briefly presented peripheral saccade targets. The results showed that targets were perceived as less curved for objects that previously changed from more circular in the periphery to more triangular in the fovea. Similarly, shapes were perceived as more curved for objects that previously changed from triangular to circular. Thus, peripheral perception seems to depend not solely on the current input but also on memorized experiences, enabling predictions about the perceptual consequences of saccadic eye movements. |
Florian Hintz; Antje S. Meyer Prediction and production of simple mathematical equations: Evidence from visual world eye-tracking Journal Article In: PLoS ONE, vol. 10, no. 7, pp. e0130766, 2015. @article{Hintz2015, The relationship between the production and the comprehension systems has recently become a topic of interest for many psycholinguists. It has been argued that these systems are tightly linked and in particular that listeners use the production system to predict upcoming content. In this study, we tested how similar production and prediction processes are in a novel version of the visual world paradigm. Dutch speaking participants (native speakers in Experiment 1; German-Dutch bilinguals in Experiment 2) listened to mathematical equations while looking at a clock face featuring the numbers 1 to 12. On alternating trials, they either heard a complete equation ("three plus eight is eleven") or they heard the first part ("three plus eight is") and had to produce the result ("eleven") themselves. Participants were encouraged to look at the relevant numbers throughout the trial. Their eye movements were recorded and analyzed. We found that the participants' eye movements in the two tasks were overall very similar. They fixated the first and second number of the equations shortly after they were mentioned, and fixated the result number well before they named it on production trials and well before the recorded speaker named it on comprehension trials. However, all fixation latencies were shorter on production than on comprehension trials. These findings suggest that the processes involved in planning to say a word and anticipating hearing a word are quite similar, but that people are more aroused or engaged when they intend to respond than when they merely listen to another person. |
Elizabeth R. Goldenberg; Scott P. Johnson Category generalization in a new context: The role of visual attention Journal Article In: Infant Behavior and Development, vol. 38, pp. 49–56, 2015. @article{Goldenberg2015, Infants and children have difficulty categorizing objects in new contexts. However, learning in both same and varied contexts can help young word learners overcome contextual learning difficulties. We examined the relation between infants' visual attention to the category member and background context during learning and their ability to generalize a new category member in a new context. Of particular interest is how this relation is affected by learning in various contextual conditions. Infants (16-20 months; n= 48) were presented with eight novel noun categories in one of three contextual conditions (same context, varied context, or a combination of same and varied contexts), and tested for their generalization ability in a new context. Context was defined as the colored and patterned fabric upon which the object was presented. Results suggest that visual attention during learning is associated with category generalization ability in a new context only for infants whose learning took place in a combination of same and varied background contexts. The results are discussed in terms of the mechanisms by which context affects generalization. |
Julie D. Golomb Divided spatial attention and feature-mixing errors Journal Article In: Attention, Perception, and Psychophysics, vol. 77, no. 8, pp. 2562–2569, 2015. @article{Golomb2015, Spatial attention is thought to play a critical role in feature binding. However, often multiple objects or locations are of interest in our environment, and we need to shift or split attention between them. Recent evidence has demonstrated that shifting and splitting spatial attention results in different types of feature-binding errors. In particular, when two locations are simultaneously sharing attentional resources, subjects are susceptible to feature-mixing errors; that is, they tend to report a color that is a subtle blend of the target color and the color at the other attended location. The present study was designed to test whether these feature-mixing errors are influenced by target-distractor similarity. Subjects were cued to split attention across two different spatial locations, and were subsequently presented with an array of colored stimuli, followed by a postcue indicating which color to report. Target-distractor similarity was manipulated by varying the distance in color space between the two attended stimuli. Probabilistic modeling in all cases revealed shifts in the response distribution consistent with feature-mixing errors; however, the patterns differed considerably across target-distractor color distances. With large differences in color, the findings replicated the mixing result, but with small color differences, repulsion was instead observed, with the reported target color shifted away from the other attended color. |
Pablo Gomez; Roger Ratcliff; Russ Childers Pointing, looking at, and pressing keys: A diffusion model account of response modality Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 41, no. 6, pp. 1515–1523, 2015. @article{Gomez2015, Accumulation of evidence models of perceptual decision making have been able to account for data from a wide range of domains at an impressive level of precision. In particular, Ratcliff's (1978) diffusion model has been used across many different 2-choice tasks in which the response is executed via a key-press. In this article, we present 2 experiments in which we used a letter-discrimination task exploring 3 central aspects of a 2-choice task: the discriminability of the stimulus, the modality of the response execution (eye movement, key pressing, and pointing on a touchscreen), and the mapping of the response areas for the eye movement and the touchscreen conditions (consistent vs. inconsistent). We fitted the diffusion model to the data from these experiments and examined the behavior of the model's parameters. Fits of the model were consistent with the hypothesis that the same decision mechanism is used in the task with 3 different response methods. Drift rates are affected by the duration of the presentation of the stimulus while the response execution time changed as a function of the response modality. |
Claudia C. Gonzalez; Mark Mon-Williams; Melanie R. Burke Children and older adults exhibit distinct sub-optimal cost-benefit functions when preparing to move their eyes and hands Journal Article In: PLoS ONE, vol. 10, no. 2, pp. e0117783, 2015. @article{Gonzalez2015, Numerous activities require an individual to respond quickly to the correct stimulus. The pro-vision of advance information allows response priming but heightened responses can cause errors (responding too early or reacting to the wrong stimulus). Thus, a balance is re-quired between the online cognitive mechanisms (inhibitory and anticipatory) used to pre-pare and execute a motor response at the appropriate time. We investigated the use of advance information in 71 participants across four different age groups: (i) children, (ii) young adults, (iii) middle-aged adults, and (iv) older adults. We implemented 'cued' and 'non-cued' conditions to assess age-related changes in saccadic and touch responses to targets in three movement conditions: (a) Eyes only; (b) Hands only; (c) Eyes and Hand. Children made less saccade errors compared to young adults, but they also exhibited lon-ger response times in cued versus non-cued conditions. In contrast, older adults showed faster responses in cued conditions but exhibited more errors. The results indicate that young adults (18–25 years) achieve an optimal balance between anticipation and execu-tion. In contrast, children show benefits (few errors) and costs (slow responses) of good in-hibition when preparing a motor response based on advance information; whilst older adults show the benefits and costs associated with a prospective response strategy (i.e., good anticipation). |
Michele Graffeo; Luca Polonio; Nicolao Bonini Individual differences in competent consumer choice: The role of cognitive reflection and numeracy skills Journal Article In: Frontiers in Psychology, vol. 6, pp. 844, 2015. @article{Graffeo2015, In this paper, we investigate whether cognitive reflection and numeracy skills affect the quality of the consumers' decision-making process in a purchase decision context. In a first (field) experiment, an identical product was on sale in two shops with different initial prices and discounts. One of the two deals was better than the other and the consumers were asked to choose the best one and to describe which arithmetic operations they used to solve the problem; then they were asked to complete the numeracy scale (Lipkus et al., 2001). The choice procedures used by the consumers were classified as "complete decision approach" when all the arithmetic operations needed to solve the problem were computed, and as "partial decision approach" when only some operations were computed. A mediation model shows that higher numeracy is associated with use of the complete decision approach. In turn, this approach is positively associated with the quality of the purchase decision. Given that these findings highlight the importance of the decision processes, in a second (laboratory) experiment we used a supplementary method to study the type of information search used by the participants: eye-tracking. In this experiment the participants were presented with decision problems similar to those used in Experiment 1 and they completed the Lipkus numeracy scale and the Cognitive Reflection Test (CRT; Frederick, 2005). Participants with a high CRT score chose the best deal more frequently, and showed a more profound and detailed information search pattern compared to participants with a low CRT score. Overall, results indicate that higher levels of cognitive reflection and numeracy skills predict the use of a more thorough decision process (measured with two different techniques: retrospective verbal reports and eye movements). In both experiments the decision process is a crucial factor which greatly affects the quality of the purchase decision. |
Joshua A. Granek; Lauren E. Sergio Evidence for distinct brain networks in the control of rule-based motor behavior Journal Article In: Journal of Neurophysiology, vol. 114, no. 2, pp. 1298–1309, 2015. @article{Granek2015, Reach guidance when the spatial location of the viewed target and hand movement are incongruent (i.e., decoupled) necessitates use of explicit cognitive rules (strategic control) or implicit recalibration of gaze and limb position (senso- rimotor recalibration). In a patient with optic ataxia (OA) and bilateral superior parietal lobule damage, we recently demonstrated an in- creased reliance on strategic control when the patient performed a decoupled reach (Granek JA, Pisella L, Stemberger J, Vighetto A, Rossetti Y, Sergio LE. PLoS One 8: e86138, 2013). To more generally understand the fundamental mechanisms of decoupled visuomotor control and to more specifically test whether we could distinguish these two modes of movement control, we tested healthy participants in a cognitively demanding dual task. Participants continuously counted backward while simultaneously reaching toward horizontal (left or right) or diagonal (equivalent to top-left or top-right) targets with either veridical or rotated (90°) cursor feedback. By increasing the overall neural load and selectively compromising potentially overlapping neural circuits responsible for strategic control, the com- plex dual task served as a noninvasive means to disrupt the integration of a cognitive rule into a motor action. Complementary to our previous results observed in patients with optic ataxia, here our dual task led to greater performance deficits during movements that re- quired an explicit rule, implying a selective disruption of strategic control in decoupled reaching. Our results suggest that distinct neural processing is required to control these different types of reaching because in considering the current results and previous patient results together, the two classes of movement could be differentiated depend- ing on the type of interference. |
Leigh D. Grant; Alison C. Bowling Gambling attitudes and beliefs predict attentional bias in non-problem gamblers Journal Article In: Journal of Gambling Studies, vol. 31, no. 4, pp. 1487–1503, 2015. @article{Grant2015, Problem gambling has been identified as a public health concern in Australia, and a considerable proportion of regular gamblers may be at risk of developing gambling related problems. Attentional bias to salient cues has been observed in substance addictions, and to some extent, in problem gamblers. This bias appears to be indicative of an increase in sensitisation to salient cues as a result of continued reforcement of a related behaviour. To test for an attentional bias to gambling-related stimuli in non-problem gamblers, the relationships between gambling frequency, gambling attitudes and beliefs (GABS-23), and attentional bias were investigated. Participants (N = 38) viewed simultaneous pairs of gambling-related and neutral images and performed a dot probe task, during which their eye-movements were recorded. This enabled both direct and indirect measures of attentional bias to be obtained. Gambling frequency and GABS-23 scores predicted both direct and indirect measures of a bias in the maintenance of attention to gambling cues. No bias in attentional engagement was found. These results suggest that regular gamblers who have not yet developed any related problems show signs of sensitisation to gambling cues and may be at risk of progressing further towards problem gambling. |
Michael J. Gray; Hans Peter Frey; Tommy J. Wilson; John J. Foxe Oscillatory recruitment of bilateral visual cortex during spatial attention to competing rhythmic inputs Journal Article In: Journal of Neuroscience, vol. 35, no. 14, pp. 5489–5503, 2015. @article{Gray2015, Selective attention uses temporal regularity of relevant inputs to bias the phase of ongoing population-level neuronal oscillations. This phase entrainment streamlines processing, allowing attended information to arrive at moments of high neural excitability. How entrainment resolves competition between spatially segregated inputs during visuospatial tasks is not yet established. Using high-density electroencephalography in humans, a bilateral entrainment response to the rhythm (1.3 or 1.5 Hz) of an attended stimulation stream was observed, concurrent with a considerably weaker contralateral entrainment to a competing rhythm. That ipsilateral visual areas strongly entrained to the attended stimulus is notable because competitive inputs to these regions were being driven at an entirely different rhythm. Strong modulations of phase locking and weak modulations of single-trial power suggest that entrainment was primarily driven by phase-alignment of ongoing oscillatory activity. In addition, interhemispheric differences in entrained phase were found to be modulated by attended hemifield, implying that the bilateral nature of the response reflected a functional flow of information between hemispheres. This modulation was strongest at the third of at least four harmonics that were strongly entrained. Ipsilateral increases in alpha-band (8-12 Hz) power were also observed during bilateral entrainment, reflecting suppression of the ignored stimulation stream. Furthermore, both entrainment and alpha lateralization significantly affected task performance. We conclude that oscillatory entrainment is a functionally relevant mechanism that synchronizes endogenous activity across the cortical hierarchy to resolve spatial competition. We further speculate that concurrent suppression of ignored input might facilitate the widespread propagation of attended information during spatial attention. |
Nicola J. Gregory; Beatriz López; Gemma Graham; Paul Marshman; Sarah Bate; Niko Kargas Reduced gaze following and attention to heads when viewing a "live" social scene Journal Article In: PLoS ONE, vol. 10, no. 4, pp. e0121792, 2015. @article{Gregory2015, Social stimuli are known to both attract and direct our attention, but most research on social attention has been conducted in highly controlled laboratory settings lacking in social context. This study examined the role of social context on viewing behaviour of participants whilst they watched a dynamic social scene, under three different conditions. In two social groups, participants believed they were watching a live webcam of other participants. The socially-engaged group believed they would later complete a group task with the people in the video, whilst the non-engaged group believed they would not meet the people in the scene. In a third condition, participants simply free-viewed the same video with the knowledge that it was pre-recorded, with no suggestion of a later interaction. Results demonstrated that the social context in which the stimulus was viewed significantly influenced viewing behaviour. Specifically, participants in the social conditions allocated less visual attention towards the heads of the actors in the scene and followed their gaze less than those in the free-viewing group. These findings suggest that by underestimating the impact of social context in social attention, researchers risk coming to inaccurate conclusions about how we attend to others in the real world. |
Joseph C. Griffis; Abdurahman S. Elkhetali; Ryan J. Vaden; Kristina M. Visscher Distinct effects of trial-driven and task set-related control in primary visual cortex Journal Article In: NeuroImage, vol. 120, pp. 285–297, 2015. @article{Griffis2015, Task sets are task-specific configurations of cognitive processes that facilitate task-appropriate reactions to stimuli. While it is established that the trial-by-trial deployment of visual attention to expected stimuli influences neural responses in primary visual cortex (V1) in a retinotopically specific manner, it is not clear whether the mechanisms that help maintain a task set over many trials also operate with similar retinotopic specificity. Here, we address this question by using BOLD fMRI to characterize how portions of V1 that are specialized for different eccentricities respond during distinct components of an attention-demanding discrimination task: cue-driven preparation for a trial, trial-driven processing, task-initiation at the beginning of a block of trials, and task-maintenance throughout a block of trials. Tasks required either unimodal attention to an auditory or a visual stimulus or selective intermodal attention to the visual or auditory component of simultaneously presented visual and auditory stimuli. We found that while the retinotopic patterns of trial-driven and cue-driven activity depended on the attended stimulus, the retinotopic patterns of task-initiation and task-maintenance activity did not. Further, only the retinotopic patterns of trial-driven activity were found to depend on the presence of inter-modal distraction. Participants who performed well on the intermodal selective attention tasks showed strong task-specific modulations of both trial-driven and task-maintenance activity. Importantly, task-related modulations of trial-driven and task-maintenance activity were in opposite directions. Together, these results confirm that there are (at least) two different processes for top-down control of V1: One, working trial-by-trial, differently modulates activity across different eccentricity sectors - portions of V1 corresponding to different visual eccentricities. The second process works across longer epochs of task performance, and does not differ among eccentricity sectors. These results are discussed in the context of previous literature examining top-down control of visual cortical areas. |
Marcus Grueschow; Rafael Polania; Todd A. Hare; Christian C. Ruff Automatic versus choice-dependent value representations in the human brain Journal Article In: Neuron, vol. 85, no. 4, pp. 874–885, 2015. @article{Grueschow2015, The subjective values of choice options can impact on behavior in two fundamentally different types of situations: first, when people explicitly base their actions on such values, and second, when values attract attention despite being irrelevant for current behavior. Here we show with functional magnetic resonance imaging (fMRI) that these two behavioral functions of values are encoded in distinct regions of the human brain. In the medial prefrontal cortex, value-related activity is enhanced when subjective value becomes choice-relevant, and the magnitude of this increase relates directly to the outcome and reliability of the value-based choice. In contrast, activity in the posterior cingulate cortex represents values similarly when they are relevant or irrelevant for the present choice, and the strength of this representation predicts attentional capture by choice-irrelevant values. Our results suggest that distinct components of the brain's valuation network encode value in context-dependent manners that serve fundamentally different behavioral aims. |
Tjerk P. Gutteling; Luc P. J. Selen; W. Pieter Medendorp Parallax-sensitive remapping of visual space in occipito-parietal alpha-band activity during whole-body motion Journal Article In: Journal of Neurophysiology, vol. 113, pp. 1574–1584, 2015. @article{Gutteling2015, Despite the constantly changing retinal image due to eye, head, and body movements, we are able to maintain a stable representation of the visual environment. Various studies on retinal image shifts caused by saccades have suggested that occipital and parietal areas correct for these perturbations by a gaze-centered remapping of the neural image. However, such a uniform, rotational, remapping mechanism cannot work during translations when objects shift on the retina in a more complex, depth-dependent fashion due to motion parallax. Here we tested whether the brain's activity patterns show parallax-sensitive remapping of remembered visual space during whole-body motion. Under continuous recording of electroencephalography (EEG), we passively translated human subjects while they had to remember the location of a world-fixed visual target, briefly presented in front of or behind the eyes' fixation point prior to the motion. Using a psychometric approach we assessed the quality of the memory update, which had to be made based on vestibular feedback and other extraretinal motion cues. All subjects showed a variable amount of parallax-sensitive updating errors, i.e., the direction of the errors depended on the depth of the target relative to fixation. The EEG recordings show a neural correlate of this parallax-sensitive remapping in the alpha-band power at occipito-parietal electrodes. At parietal electrodes, the strength of these alpha-band modulations correlated significantly with updating performance. These results suggest that alpha-band oscillatory activity reflects the time-varying updating of gaze-centered spatial information during parallax-sensitive remapping during whole-body motion. |
Ralf Engbert; Hans A. Trukenbrod; Simon Barthelmé; Felix A. Wichmann Spatial statistics and attentional dynamics in scene viewing Journal Article In: Journal of Vision, vol. 15, no. 1, pp. 1–17, 2015. @article{Engbert2015, In humans and in foveated animals visual acuity is highly concentrated at the center of gaze, so that choosing where to look next is an important example of online, rapid decision-making. Computational neuroscientists have developed biologically-inspired models of visual attention, termed saliency maps, which successfully predict where people fixate on average. Using point process theory for spatial statistics, we show that scanpaths contain, however, important statistical structure, such as spatial clustering on top of distributions of gaze positions. Here, we develop a dynamical model of saccadic selection that accurately predicts the distribution of gaze positions as well as spatial clustering along individual scanpaths. Our model relies on activation dynamics via spatially-limited (foveated) access to saliency information, and, second, a leaky memory process controlling the re-inspection of target regions. This theoretical framework models a form of context-dependent decision-making, linking neural dynamics of attention to behavioral gaze data. |
Jonas Everaert; Ernst H. W. Koster Interactions among emotional attention, encoding, and retrieval of ambiguous information: An eye-tracking study Journal Article In: Emotion, vol. 15, no. 5, pp. 539–543, 2015. @article{Everaert2015, Emotional biases in attention modulate encoding of emotional material into long-term memory, but little is known about the role of such attentional biases during emotional memory retrieval. The present study investigated how emotional biases in memory are related to attentional allocation during retrieval. Forty-nine individuals encoded emotionally positive and negative meanings derived from ambiguous information and then searched their memory for encoded meanings in response to a set of retrieval cues. The remember/know/new procedure was used to classify memories as recollection-based or familiarity-based, and gaze behavior was monitored throughout the task to measure attentional allocation. We found that a bias in sustained attention during recollection-based, but not familiarity-based, retrieval predicted subsequent memory bias toward positive versus negative material following encoding. Thus, during emotional memory retrieval, attention affects controlled forms of retrieval (i.e., recollection) but does not modulate relatively automatic, familiarity-based retrieval. These findings enhance understanding of how distinct components of attention regulate the emotional content of memories. Implications for theoretical models and emotion regulation are discussed. |
Michel Failing; Tom Nissens; Daniel Pearson; Mike Le Pelley; Jan Theeuwes Oculomotor capture by stimuli that signal the availability of reward Journal Article In: Journal of Neurophysiology, vol. 114, no. 4, pp. 2316–2327, 2015. @article{Failing2015, It is well known that eye movement patterns are influenced by both goal- and salience-driven factors. Recent studies, however, have demonstrated that objects that are nonsalient and task irrelevant can still capture our eyes if moving our eyes to those objects has previously produced reward. Here we demonstrate that training such an association between eye movements to an object and delivery of reward is not needed. Instead, an object that merely signals the availability of reward captures the eyes even when it is physically nonsalient and never relevant for the task. Furthermore, we show that oculomotor capture by reward is more reliably observed in saccades with short latencies. We conclude that a stimulus signaling high reward has the ability to capture the eyes independently of bottom-up physical salience or top-down task relevance and that the effect of reward affects early selection processes. |
Rebecca M. Foerster; Werner X. Schneider Expectation violations in sensorimotor sequences: Shifting from LTM-based attentional selection to visual search Journal Article In: Annals of the New York Academy of Sciences, vol. 1339, no. 1, pp. 45–59, 2015. @article{Foerster2015, Long-term memory (LTM) delivers important control signals for attentional selection. LTM expectations have an important role in guiding the task-driven sequence of covert attention and gaze shifts, especially in well-practiced multistep sensorimotor actions. What happens when LTM expectations are disconfirmed? Does a sensory-based visual-search mode of attentional selection replace the LTM-based mode? What happens when prior LTM expectations become valid again? We investigated these questions in a computerized version of the number-connection test. Participants clicked on spatially distributed numbered shapes in ascending order while gaze was recorded. Sixty trials were performed with a constant spatial arrangement. In 20 consecutive trials, either numbers, shapes, both, or no features switched position. In 20 reversion trials, participants worked on the original arrangement. Only the sequence-affecting number switches elicited slower clicking, visual search-like scanning, and lower eye-hand synchrony. The effects were neither limited to the exchanged numbers nor to the corresponding actions. Thus, expectation violations in a well-learned sensorimotor sequence cause a regression from LTM-based attentional selection to visual search beyond deviant-related actions and locations. Effects lasted for several trials and reappeared during reversion. |
Rebecca M. Foerster; Werner X. Schneider Anticipatory eye movements in sensorimotor actions: On the role of guiding fixations during learning Journal Article In: Cognitive Processing, vol. 16, no. 1, pp. 227–231, 2015. @article{Foerster2015a, During object-based sensorimotor tasks, humans look at target locations for subsequent hand actions. These anticipatory eye movements or guiding fixations seem to be necessary for a successful perfor- mance. By practicing such a sensorimotor task, humans become faster and perform fewer guiding fixations (Foer- ster and Schneider, In Prep; Foerster et al. in J Vis 11(7):9:1–16, 2011). We aimed at clarifying whether this decrease in guiding fixations is the cause or effect of faster task completion time. Participants may learn to use less visual input (fewer fixations) allowing shorter completion times. Alternatively, participants may speed up their hand movements (e.g., more efficient motor control) leaving less time for visual intake. The latter would imply that the number of fixations is directly connected to task speed. We investigated the relationship between the number of fixa- tions and task speed in a computerized version of the number connection task (Foerster and Schneider in Ann N Y Acad Sci 2015. doi:10.1111/nyas.12729). Eye move- ments were recorded while participants clicked in ascend- ing order on nine numbered circles. In 90 learning trials, they clicked the sequence with a constant spatial configu- ration as fast as possible. In the subsequent experimental phase, they should perform 30 trials again under high- speed instruction and 30 trials under slow-speed instruc- tion. During slow-speed instruction, fixation rates were & Rebecca M. Foerster rebecca.foerster@uni-bielefeld.de 1 Department of Psychology, Bielefeld University, Bielefeld, Germany 2 Cognitive Interaction Technology - Center of Excellence (CITEC), Bielefeld University, P. O. Box 100131, 33501 Bielefeld, Germany lower with longer fixation durations and more fixations were performed than during high-speed instruction. The results suggest that the number of fixations depends on both the need for visual intake and task completion time. It seems that the decrease in anticipatory eye movements through sensorimotor learning is at the same time a result and a cause of faster task performance. |
Tom Foulsham; Maria Lock How the eyes tell lies: Social gaze during a preference task Journal Article In: Cognitive Science, vol. 39, no. 7, pp. 1704–1726, 2015. @article{Foulsham2015, Social attention is thought to require detecting the eyes of others and following their gaze. To be effective, observers must also be able to infer the person's thoughts and feelings about what he or she is looking at, but this has only rarely been investigated in laboratory studies. In this study, participants' eye movements were recorded while they chose which of four patterns they preferred. New observers were subsequently able to reliably guess the preference response by watching a replay of the fixations. Moreover, when asked to mislead the person guessing, participants changed their looking behavior and guessing success was reduced. In a second experiment, naïve participants could also guess the preference of the original observers but were unable to identify trials which were lies. These results confirm that people can spontaneously use the gaze of others to infer their judgments, but also that these inferences are open to deception. |
Tom P. Freeman; Ravi K. Das; Sunjeev K. Kamboj; H. Valerie Curran Dopamine urges to smoke and the relative salience of drug versus non-drug reward Journal Article In: Social Cognitive and Affective Neuroscience, vol. 10, no. 1, pp. 85–92, 2015. @article{Freeman2015, When addicted individuals are exposed to drug-related stimuli, dopamine release is thought to mediate incentive salience attribution, increasing attentional bias, craving and drug seeking. It is unclear whether dopamine acts specifically on drug cues versus other rewards, and if these effects correspond with craving and other forms of cognitive bias. Here, we administered the dopamine D2/D3 agonist pramipexole (0.5 mg) to 16 tobacco smokers in a double-blind placebo-controlled crossover design. Visual fixations on smoking and money images were recorded alongside smoking urges and fluency tasks. Pramipexole attenuated a marked bias in initial orienting towards smoking relative to money but did not alter a maintained attentional bias towards smoking. Pramipexole decreased urges to smoke retrospectively after the task but not on a state scale. Fewer smoking words were generated after pramipexole but phonological and semantic fluency were preserved. Although these treatment effects did not correlate with each other, changes in initial orienting towards smoking and money were inversely related to baseline scores. In conclusion, pramipexole can reduce the salience of an addictive drug compared with other rewards and elicit corresponding changes in smoking urges and cognitive bias. These reward-specific and baseline-dependent effects support an 'inverted-U' shaped profile of dopamine in addiction. |
Adam Frost; Matthias Niemeier Suppression and reversal of motion perception around the time of the saccade Journal Article In: Frontiers in Systems Neuroscience, vol. 9, pp. 143, 2015. @article{Frost2015, We make fast, "saccadic" eye movements to capture finely resolved foveal snapshots of the world but these saccades cause motion artefacts. The artefacts go unnoticed, perhaps because the brain suppresses them through subcortical oculomotor signals feeding back into visual cortex. Opposing views, however, claim that passive mechanisms suffice: saccadic shearing forces might render the retina insensitive to the artefacts or post-saccadic snapshots might mask them before they enter consciousness. Crucially, only active suppression could explain perceptual changes that precede saccades but existing evidence for presaccadic misperception are ill-suited for addressing this issue: Previous studies have found misperceptions of space for objects briefly flashed before saccades, but perhaps only because observers confused the timing of flashes and saccades before they could be tested ("postdiction"), and presaccadic motion perception might have appeared to decline because motion stimuli persisted past eye movement onset. Here we addressed these concerns using briefly flashed two-frame animations (50 ms) to probe people's motion sensitivity during and around saccades. We found that sensitivity declined before saccade onset, even when the probe appeared entirely outside the saccade, and this sensitivity decline was present for motion in every direction relative to saccade, ruling out problems with postdiction. Intriguingly, brief periods during the saccade produced negative sensitivity as if motion was reversed, arguably due to postsaccadic enhancement. These data suggest that motion perception is minimized during saccades through active suppression, complementing neurophysiological findings of colliculo-pulvinar projections that suppress the cortical middle temporal area around the time of the saccade. |
Anja Gampe; Anne Keitel; Moritz M. Daum Intra-individual variability and continuity of action and perception measures in infants Journal Article In: Frontiers in Psychology, vol. 6, pp. 327, 2015. @article{Gampe2015, The development of action and perception, and their relation in infancy is a central research area in socio-cognitive sciences. In this Perspective Article, we focus on the developmental variability and continuity of action and perception. At group level, these skills have been shown to consistently improve with age. We would like to raise awareness for the issue that, at individual level, development might be subject to more variable changes. We present data from a longitudinal study on the perception and production of contralateral reaching skills of infants aged 7, 8, 9, and 12 months. Our findings suggest that individual development does not increase linearly for action or for perception, but instead changes dynamically. These non-continuous changes substantially affect the relation between action and perception at each measuring point and the respective direction of causality. This suggests that research on the development of action and perception and their interrelations needs to take into account individual variability and continuity more progressively. |
Elad Ganmor; Michael S. Landy; Eero P. Simoncelli Near-optimal integration of orientation information across saccades Journal Article In: Journal of Vision, vol. 15, no. 16, pp. 1–12, 2015. @article{Ganmor2015, We perceive a stable environment despite the fact that visual information is essentially acquired in a sequence of snapshots separated by saccadic eye movements. The resolution of these snapshots varies-high in the fovea and lower in the periphery-and thus the formation of a stable percept presumably relies on the fusion of information acquired at different resolutions. To test if, and to what extent, foveal and peripheral information are integrated, we examined human orientation-discrimination performance across saccadic eye movements. We found that humans perform best when an oriented target is visible both before (peripherally) and after a saccade (foveally), suggesting that humans integrate the two views. Integration relied on eye movements, as we found no evidence of integration when the target was artificially moved during stationary viewing. Perturbation analysis revealed that humans combine the two views using a weighted sum, with weights assigned based on the relative precision of foveal and peripheral representations, as predicted by ideal observer models. However, our subjects displayed a systematic overweighting of the fovea, relative to the ideal observer, indicating that human integration across saccades is slightly suboptimal. |
Ouazna Habchi; Elodie Rey; Romain Mathieu; Christian Urquizar; Alessandro Farnè; Denis Pélisson Deployment of spatial attention without moving the eyes is boosted by oculomotor adaptation Journal Article In: Frontiers in Human Neuroscience, vol. 9, pp. 426, 2015. @article{Habchi2015, Vertebrates developed sophisticated solutions to select environmental visual information, being capable of moving attention without moving the eyes. A large body of behavioral and neuroimaging studies indicate a tight coupling between eye movements and spatial attention. The nature of this link, however, remains highly debated. Here, we demonstrate that deployment of human covert attention, measured in stationary eye conditions, can be boosted across space by changing the size of ocular saccades to a single position via a specific adaptation paradigm. These findings indicate that spatial attention is more widely affected by oculomotor plasticity than previously thought. |
Jason Haberman; Timothy F. Brady; George A. Alvarez Individual differences in ensemble perception reveal multiple, independent levels of ensemble representation Journal Article In: Journal of Experimental Psychology: General, vol. 144, no. 2, pp. 432–446, 2015. @article{Haberman2015, Ensemble perception, including the ability to “see the average” from a group of items, operates in numerous feature domains (size, orientation, speed, facial expression, etc.). Although the ubiquity of ensemble representations is well established, the large-scale cognitive architecture of this process remains poorly defined. We address this using an individual differences approach. In a series of experiments, observers saw groups of objects and reported either a single item from the group or the average of the entire group. High-level ensemble representations (e.g., average facial expression) showed complete independence from low-level ensemble representations (e.g., average orientation). In contrast, low-level ensemble representations (e.g., orientation and color) were correlated with each other, but not with high-level ensemble representations (e.g., facial expression and person identity). These results suggest that there is not a single domain-general ensemble mechanism, and that the relationship among various ensemble representations depends on how proximal they are in representational space. |
Harry H. Haladjian; Ella Wufong; Tamara L. Watson Spatial compression: Dissociable effects at the time of saccades and blinks Journal Article In: Journal of Vision, vol. 15, no. 9, pp. 1–19, 2015. @article{Haladjian2015, Various studies have identified systematic errors, such as spatial compression, when observers report the locations of objects displayed around the time of saccades. Localization errors also occur when holding spatial representations in visual working memory. Such errors, however, have not been examined in the context of eye blinks. In this study, we examined the effects of blinks and saccades when observers reproduced the locations of a set of briefly presented, randomly placed discs. Performance was compared with a fixation-only condition in which observers simply held these representations in working memory for the same duration; this allowed us to elucidate the relationship between the perceptual phenomena related to blinks, saccades, and visual working memory. Our results indicate that the same amount of spatial compression is experienced prior to a blink as is experienced in the control fixation-only condition, suggesting that blinks do not increase compression above that occurring from holding a spatial representation in visual memory. Saccades, however, tend to increase these compression effects and produce translational shifts both toward and away from saccade targets (depending on the time of the saccade onset in relation to the stimulus offset). A higher numerosity recall capacity was also observed when stimuli were presented prior to a blink in comparison with the other conditions. These findings reflect key differences underlying blinks and saccades in terms of spatial compression and translational shifts. Such results suggest that separate mechanisms maintain perceptual stability across these visual events. |
Shahrbanoo Hamel; Dominique Houzet; Denis Pellerin; Nathalie Guyader Does color influence eye movements while exploring videos? Journal Article In: Journal of Eye Movement Research, vol. 8, no. 1, pp. 1–10, 2015. @article{Hamel2015, Although visual attention studies consider color as one of the most important features in guiding visual attention, few studies have investigated how color influences eye movements while viewing natural scenes without any particular task. To better understand the visual features that drive attention, the aim of this paper was to quantify the influence of color on eye movements when viewing dynamic natural scenes. The influence of color was investigated by comparing the eye positions of several observers eye-tracked while viewing video stimuli in two conditions: color and grayscale. The comparison was made using the dispersion between the eye positions of observers, the number of attractive regions measured with a clustering method applied to the eye positions, and by comparing eye positions to the predictions of a saliency model. The mean amplitude of saccades and the mean duration of fixations were compared as well. Globally, a slight influence of color on eye movements was measured; only the number of attractive regions for color stimuli was slightly higher than for grayscale stimuli. However, a luminance-based saliency model predicts the eye positions for color stimuli as efficiently as for grayscale stimuli. |
Bruce C. Hansen; Pamela J. Rakhshan; Arnold K. Ho; Sebastian Pannasch Looking at others through implicitly or explicitly prejudiced eyes Journal Article In: Visual Cognition, vol. 23, no. 5, pp. 612–642, 2015. @article{Hansen2015, It is well known that we utilize internalized representations (or schemas) to direct our eyes when exploring visual stimuli. Interestingly, our schemas for human faces are known to reflect systematic differences that are consistent with one's level of racial prejudice. However, whether one's level or type of racial prejudice can differentially regulate how we visually explore faces that are the target of prejudice is currently unknown. Here, White participants varying in their level of implicit or explicit prejudice viewed Black faces and White faces (with the latter serving as a control) while having their gaze behaviour recorded with an eye-tracker. The results show that, regardless of prejudice type (i.e., implicit or explicit), participants high in racial prejudice examine faces differently than those low in racial prejudice. Specifically, individuals high in explicit racial prejudice were more likely to fixate on the mouth region of Black faces when compared to individuals low in explicit prejudice, and exhibited less consistency in their scanning of faces irrespective of race. On the other hand, individuals high in implicit racial prejudice tended to focus on the region between the eyes, regardless of face race. It therefore seems that racial prejudice guides target-race specific patterns of looking behaviour, and may also contribute to general patterns oflooking behaviour when visually exploring human faces. |
Anthony M. Harris; Stefanie I. Becker; Roger W. Remington Capture by colour: Evidence for dimension-specific singleton capture Journal Article In: Attention, Perception, and Psychophysics, vol. 77, no. 7, pp. 2305–2321, 2015. @article{Harris2015a, Previous work on attentional capture has shown the attentional system to be quite flexible in the stimulus properties it can be set to respond to. Several different attentional "modes" have been identified. Feature search mode allows attention to be set for specific features of a target (e.g., red). Singleton detection mode sets attention to respond to any discrepant item ("singleton") in the display. Relational search sets attention for the relative properties of the target in relation to the distractors (e.g., redder, larger). Recently, a new attentional mode was proposed that sets attention to respond to any singleton within a particular feature dimension (e.g., colour; Folk & Anderson, 2010). We tested this proposal against the predictions of previously established attentional modes. In a spatial cueing paradigm, participants searched for a colour target that was randomly either red or green. The nature of the attentional control setting was probed by presenting an irrelevant singleton cue prior to the target display and assessing whether it attracted attention. In all experiments, the cues were red, green, blue, or a white stimulus rapidly rotated (motion cue). The results of three experiments support the existence of a "colour singleton set," finding that all colour cues captured attention strongly, while motion cues captured attention only weakly or not at all. Notably, we also found that capture by motion cues in search for colour targets was moderated by their frequency; rare motion cues captured attention (weakly), while frequent motion cues did not. |
Jesse A. Harris Structure modulates similarity-based interference in sluicing: An eye tracking study Journal Article In: Frontiers in Psychology, vol. 6, pp. 1839, 2015. @article{Harris2015, In cue-based content-addressable approaches to memory, a target and its competitors are retrieved in parallel from memory via a fast, associative cue-matching procedure under a severely limited focus of attention. Such a parallel matching procedure could in principle ignore the serial order or hierarchical structure characteristic of linguistic relations. I present an eye tracking while reading experiment that investigates whether the sentential position of a potential antecedent modulates the strength of similarity-based interference, a well-studied effect in which increased similarity in features between a target and its competitors results in slower and less accurate retrieval overall. The manipulation trades on an independently established Locality bias in sluiced structures to associate a wh-remnant (which ones) in clausal ellipsis with the most local correlate (some wines), as in "The tourists enjoyed some wines, but I don't know which ones." The findings generally support cue-based parsing models of sentence processing that are subject to similarity-based interference in retrieval, and provide additional support to the growing body of evidence that retrieval is sensitive to both the structural position of a target antecedent and its competitors, and the specificity of retrieval cues. |
Jonathan W. Harris; Christopher D. Cowper-Smith; Raymond M. Klein; David A. Westwood Further evidence against a momentum explanation for IOR Journal Article In: PLoS ONE, vol. 10, no. 4, pp. e0123666, 2015. @article{Harris2015b, Reaction times to targets presented in the same location as a preceding cue are greater than those to targets presented opposite the cued location. This observation can be explained as a result of inhibition at the attended location (IOR), or as facilitation at the location opposite the cue (opposite facilitation effect or OFE). Past research has demonstrated that IOR is observed reliably, whereas OFE is observed only occasionally. The present series of four experiments allows us to determine whether or not OFE can be explained by eye movements as suggested by previous authors. Participants' eye movements were monitored as they were presented with an array of four placeholders aligned with the four cardinal axes. Exogenous cues and targets were presented successively. Participants (N=37) completed either: i.) cue-manual and cue-saccade experiments, ignoring the cue and then responding with a keypress or saccade, respectively, or ii.) manual-manual and saccade-saccade experiments, responding to both the cue and the target with a keypress or saccade respectively. Results demonstrated a reliable IOR effect in each of the four experiments (reaction time greater for same versus adjacent and opposite cue-target trials). None of the four experiments demonstrated evidence of an OFE (reaction times were not significantly lower for opposite versus adjacent cue-target trials). These results are inconsistent with a momentum-based account of cue-target task performance, and furthermore suggest that the OFE cannot be attributed to occasional eye movements to the cue and/or target in previous studies. |
Nabil Hasshim; Benjamin A. Parris In: Attention, Perception, and Psychophysics, vol. 77, no. 8, pp. 2601–2610, 2015. @article{Hasshim2015, Conflict in the Stroop task is thought to come from various stages of processing, including semantics. Two-to-one response mappings, in which two response-set colors share a common response location, have been used to isolate stimulus-stimulus (semantic) from stimulus-response conflict in the Stroop task. However, the use of congruent trials as a baseline means that the measured effects could be exaggerated by facilitation, and recent research using neutral, non-color-word trials as a baseline has supported this notion. In the present study, we sought to provide evidence for stimulus-stimulus conflict using an oculomotor Stroop task and an early, preresponse pupillometric measure of effort. The results provided strong (Bayesian) evidence for no statistical difference between two-to-one response-mapping trials and neutral trials in both saccadic response latencies and preresponse pupillometric measures, supporting the notion that the difference between same-response and congruent trials indexes facilitation in congruent trials, and not stimulus-stimulus conflict, thus providing evidence against the presence of semantic conflict in the Stroop task. We also demonstrated the utility of preresponse pupillometry in measuring Stroop interference, supporting the idea that pupillary effects are not simply a residue of making a response. |
Rebecca Haworth; Stephanie Sobey; Jill M. Chorney; Michael Bezuhly; Paul Hong Measuring attentional bias in children with prominent ears: A prospective eye-tracking study Journal Article In: Journal of Plastic, Reconstructive & Aesthetic Surgery, vol. 68, no. 12, pp. 1662–1666, 2015. @article{Haworth2015, Background and aim: When observing new faces, most people focus their attention on the central triangle of the face containing the eyes, nose and mouth. When viewing faces with prominent ears, observers may divert their attention from the central triangle. The objective of this study was to determine whether there was an objective attentional bias to prominent ears in comparison to non-prominent ears. Methods: A total of 24 naïve participants (13 female; mean age 22.88 years) viewed 15 photographs of children with bilateral prominent ears, unilateral prominent ears and non-prominent ears. Both pre- and post-otoplasty photographs of two patients were included. The eye movements of participants were recorded using the EyeLink 1000, a table-mounted eye-tracking device. Results: Overall, the participants spent more time looking at the ear regions for faces with prominent ears in comparison to faces without prominent ears (p = 0.007 |
Taylor R. Hayes; Alexander A. Petrov; Per B. Sederberg Do we really become smarter when our fluid-intelligence test scores improve? Journal Article In: Intelligence, vol. 48, pp. 1–14, 2015. @article{Hayes2015, Recent reports of training-induced gains on fluid intelligence tests have fueled an explosion of interest in cognitive training-now a billion-dollar industry. The interpretation of these results is questionable because score gains can be dominated by factors that play marginal roles in the scores themselves, and because intelligence gain is not the only possible explanation for the observed control-adjusted far transfer across tasks. Here we present novel evidence that the test score gains used to measure the efficacy of cognitive training may reflect strategy refinement instead of intelligence gains. A novel scanpath analysis of eye movement data from 35 participants solving Raven's Advanced Progressive Matrices on two separate sessions indicated that one-third of the variance of score gains could be attributed to test-taking strategy alone, as revealed by characteristic changes in eye-fixation patterns. When the strategic contaminant was partialled out, the residual score gains were no longer significant. These results are compatible with established theories of skill acquisition suggesting that procedural knowledge tacitly acquired during training can later be utilized at posttest. Our novel method and result both underline a reason to be wary of purported intelligence gains, but also provide a way forward for testing for them in the future. |
Andreas Gartus; Nicolas Klemer; Helmut Leder The effects of visual context and individual differences on perception and evaluation of modern art and graffiti art Journal Article In: Acta Psychologica, vol. 156, pp. 64–76, 2015. @article{Gartus2015, Traditionally, artworks are seen as autonomous objects that stand (or should stand) on their own. However, at least since the emergence of Conceptual Art in the 1920s and Pop Art in the 1960s, art lacks any distinctive perceptual features that define it as such. Art, therefore, cannot be defined without reference to its context. Some studies have shown that context affects the evaluation of artworks, and that specific contexts (street for graffiti art, museum for modern art) elicit specific effects (Gartus & Leder, 2014). However, it is yet unclear how context changes perception and appreciation processes. In our study we measured eye-movements while participants (64 psychology undergraduates, 48% women) perceived and evaluated beauty, interest, emotional valence, as well as perceived style for modern art and graffiti art embedded into either museum or street contexts. For modern art, beauty and interest ratings were higher in a museum than in a street context, but context made no difference for the ratings of graffiti art. Importantly, we also found an interaction of context and individual interest in graffiti for beauty and interest ratings, as well as for number of fixations. Analyses of eye-movements also revealed that viewing times were in general significantly longer in museum than in street contexts. We conclude that context can have an important influence on aesthetic appreciation. However, some effects depend also on the style of the artworks and the individual art interests of the viewers. |
B. P. Geelen; Alexander H. Wertheim The prevalence effect in lateral masking and its relevance for visual search Journal Article In: Experimental Brain Research, vol. 233, no. 4, pp. 1119–1124, 2015. @article{Geelen2015, In stimulus displays with or without a single target amid 1,644 identical distractors, target prevalence was varied between 20, 50 and 80 %. Maximum gaze deviation was measured to determine the strength of lateral masking in these arrays. The results show that lateral masking was strongest in the 20 % prevalence condition, which differed significantly from both the 50 and 80 % prevalence conditions. No difference was observed between the latter two. This pattern of results corresponds to that found in the literature on the prevalence effect in visual search (stronger lateral masking corresponding to longer search times). The data add to similar findings reported earlier (Wertheim et al. in Exp Brain Res, 170:387-402, 2006), according to which the effects of many well-known factors in visual search correspond to those on lateral masking. These were the effects of set size, disjunctions versus conjunctions, display area, distractor density, the asymmetry effect (Q vs. O's) and viewing distance. The present data, taken together with those earlier findings, may lend credit to a causal hypothesis that lateral masking could be a more important mechanism in visual search than usually assumed. |
Joy J. Geng; Zachary Blumenfeld; Terence L. Tyson; Michael J. Minzenberg Pupil diameter reflects uncertainty in attentional selection during visual search Journal Article In: Frontiers in Human Neuroscience, vol. 9, pp. 453, 2015. @article{Geng2015, Pupil diameter has long been used as a metric of cognitive processing. However, recent advances suggest that the cognitive sources of change in pupil size may reflect LC-NE function and the calculation of unexpected uncertainty in decision processes (Aston-Jones & Cohen, 2005b; Yu & Dayan, 2005). In the current experiments, we explored the role of uncertainty in attentional selection on task-evoked changes in pupil diameter during visual search. We found that task-evoked changes in pupil diameter were related to uncertainty during attentional selection as measured by reaction time and performance accuracy (Experiments 1-2). Control analyses demonstrated that the results are unlikely to be due to error monitoring or response uncertainty. Our results suggest that pupil diameter can be used as an implicit metric of uncertainty in ongoing attentional selection requiring effortful control processes. |
Peggy Gerardin; Judith Nicolas; Alessandro Farnè; Denis Pélisson Increasing attentional load boosts saccadic adaptation Journal Article In: Investigative Ophthalmology & Visual Science, vol. 56, no. 11, pp. 6304–6312, 2015. @article{Gerardin2015, PURPOSE: Visual exploration relies on saccadic eye movements and attention processes. Saccadic adaptation mechanisms, which calibrate the oculomotor commands to continuously maintain the accuracy of saccades, have been suggested to act at downstream (motor) and upstream (visuoattentional) levels of visuomotor transformation. Conversely, whether attention can directly affect saccadic adaptation remains unknown. To answer this question, we manipulated the level of attention engaged in a visual discrimination task performed during saccadic adaptation. METHODS: Participants performed low or high attention demanding orientation discrimination tasks on largely or faintly oriented Gabor patches, respectively, which served as targets for reactive saccades. Gabor patches systematically jumped backward during eye motion to elicit an adaptive shortening of saccades, and replaced 50 msec later (100 msec in two subjects) by a mask. Subjects judged whether Gabors' orientation was "nearly horizontal" versus "nearly vertical" (low attention demanding) or "slightly left" versus "slightly right" (high attention demanding), or made no discrimination (control task). RESULTS: We found that the build-up and the retention of adaptation of reactive saccades were larger in the "high attention demanding" condition than in the "low attention demanding" and the no-discrimination control conditions. CONCLUSIONS: These results indicate that increasing the level of attention to the perceptual processing of otherwise identical targets boosts saccadic adaptation, and suggest that saccadic adaptation mechanisms and attentional load effects may functionally share common neural substrates. |
Mónika Gergelyfi; Benvenuto Jacob; Etienne Olivier; Alexandre Zénon Dissociation between mental fatigue and motivational state during prolonged mental activity Journal Article In: Frontiers in Behavioral Neuroscience, vol. 9, pp. 176, 2015. @article{Gergelyfi2015, Mental fatigue (MF) is commonly observed following prolonged cognitive activity and can have major repercussions on the daily life of patients as well as healthy individuals. Despite its important impact, the cognitive processes involved in MF remain largely unknown. An influential hypothesis states that MF does not arise from a disruption of overused neural processes but, rather, is caused by a progressive decrease in motivation-related task engagement. Here, to test this hypothesis, we measured various neural, autonomic, psychometric and behavioral signatures of MF and motivation (EEG, ECG, pupil size, eye blinks, Skin conductance responses (SCRs), questionnaires and performance in a working memory (WM) task) in healthy volunteers, while MF was induced by Sudoku tasks performed for 120 min. Moreover extrinsic motivation was manipulated by using different levels of monetary reward. We found that, during the course of the experiment, the participants' subjective feeling of fatigue increased and their performance worsened while their blink rate and heart rate variability (HRV) increased. Conversely, reward-induced EEG, pupillometric and skin conductance signal changes, regarded as indicators of task engagement, remained constant during the experiment, and failed to correlate with the indices of MF. In addition, MF did not affect a simple reaction time task, despite the strong influence of extrinsic motivation on this task. Finally, alterations of the motivational state through monetary incentives failed to compensate the effects of MF. These findings indicate that MF in healthy subjects is not caused by an alteration of task engagement but is likely to be the consequence of a decrease in the efficiency, or availability, of cognitive resources. |
Franziska Geringswald; Anne Herbik; Wolfram Hofmüller; Michael B. Hoffmann; Stefan Pollmann Visual memory for objects following foveal vision loss Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 41, no. 5, pp. 1471–1484, 2015. @article{Geringswald2015a, Allocation of visual attention is crucial for encoding items into visual long-term memory. In free vision, attention is closely linked to the center of gaze, raising the question whether foveal vision loss entails suboptimal deployment of attention and subsequent impairment of object encoding. To investigate this question, we examined visual long-term memory for objects in patients suffering from foveal vision loss due to age-related macular degeneration. We measured patients' change detection sensitivity after a period of free scene exploration monocularly with their worse eye when possible, and under binocular vision, comparing sensitivity and eye movements to matched normal-sighted controls. A highly salient cue was used to capture attention to a nontarget location before a target change occurred in half of the trials, ensuring that change detection relied on memory. Patients' monocular and binocular sensitivity to object change was comparable to controls, even after more than 4 intervening fixations, and not significantly correlated with visual impairment. We conclude that extrafoveal vision suffices for efficient encoding into visual long-term memory. |
Franziska Geringswald; Stefan Pollmann Central and peripheral vision loss differentially affects contextual cueing in visual search Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 41, no. 5, pp. 1485–1496, 2015. @article{Geringswald2015, Visual search for targets in repeated displays is more efficient than search for the same targets in random distractor layouts. Previous work has shown that this contextual cueing is severely impaired under central vision loss. Here, we investigated whether central vision loss, simulated with gaze-contingent displays, prevents the incidental learning of contextual cues or the expression of learning, that is, the guidance of search by learned target-distractor configurations. Visual search with a central scotoma reduced contex-tual cueing both with respect to search times and gaze parameters. However, when the scotoma was subsequently removed, contextual cueing was observed in a comparable magnitude as for controls who had searched without scotoma simulation throughout the experiment. This indicated that search with a central scotoma did not prevent incidental context learning, but interfered with search guidance by learned contexts. We discuss the role of visuospatial working memory load as source of this interference. In contrast to central vision loss, peripheral vision loss was expected to prevent spatial configuration learning itself, because the restricted search window did not allow the integration of invariant local configurations with the global display layout. This expectation was confirmed in that visual search with a simulated peripheral scotoma eliminated contextual cueing not only in the initial learning phase with scotoma, but also in the subsequent test phase without scotoma. |
Steven M. Gillespie; Pia Rotshtein; Laura Jean Wells; Anthony R. Beech; Ian J. Mitchell Psychopathic traits are associated with reduced attention to the eyes of emotional faces among adult male non-offenders Journal Article In: Frontiers in Human Neuroscience, vol. 9, pp. 552, 2015. @article{Gillespie2015, Psychopathic traits are linked with impairments in emotional facial expression recognition. These impairments may, in part, reflect reduced attention to the eyes of emotional faces. Although reduced attention to the eyes has been noted among children with conduct problems and callous-unemotional traits, similar findings are yet to be found in relation to psychopathic traits among adult male participants. Here we investigated the relationship of primary (selfish, uncaring) and secondary (impulsive, antisocial) psychopathic traits with attention to the eyes among adult male non-offenders during an emotion recognition task. We measured the number of fixations, and overall dwell time, on the eyes, and the mouth of male and female faces showing the six basic emotions at varying levels of intensity. We found no relationship of primary or secondary psychopathic traits with recognition accuracy. However, primary psychopathic traits were associated with a reduced number of fixations, and lower overall dwell time, on the eyes relative to the mouth across expressions, intensity, and sex. Furthermore, the relationship of primary psychopathic traits with attention to the eyes of angry and fearful faces was influenced by the sex and intensity of the expression. We also showed that a greater number of fixations on the eyes, relative to the mouth, were associated with increased accuracy for angry and fearful expression recognition. These results are the first to show effects of psychopathic traits on attention to the eyes of emotional faces in an adult male sample, and may support amygdala based accounts of psychopathy. These findings may also have methodological implications for clinical studies of emotion recognition. |
Aline Godfroid; Shawn Loewen; Sehoon Jung; Ji-Hyun Park; Susan M. Gass; Rod Ellis Timed and untimed grammaticality judgments measure distinct types of knowledge: Evidence from eye-movement patterns Journal Article In: Studies in Second Language Acquisition, vol. 37, no. 2, pp. 269–297, 2015. @article{Godfroid2015a, Grammaticality judgment tests (GJTs) have been used to elicit data refl ecting second language (L2) speakers' knowledge of L2 grammar. However, the exact constructs measured by GJTs, whether primarily implicit or explicit knowledge, are disputed and have been argued to differ depending on test-related variables (i.e., time pressure and item grammaticality). Using eye-tracking, this study replicates the GJT results in R. Ellis (2005). Twenty native and 40 nonnative English speakers judged sentences with and without time pressure. Analyses revealed that time pressure suppressed regressions (right-to-left eye movements) in nonnative speakers only. Conversely, both groups regressed more on untimed, grammatical items. These findings suggest that timed and untimed GJTs measure different constructs, which could correspond to implicit and explicit knowledge, respectively. In particular, they point to a difference in the levels of automatic and controlled processing involved in responding to the timed and untimed tests. Furthermore, untimed grammatical items may induce GJT- specific task effects. |
Hayward J. Godwin; Tamaryn Menneer; Kyle R. Cave; Michael Thaibsyah; Nick Donnelly The effects of increasing target prevalence on information processing during visual search Journal Article In: Psychonomic Bulletin & Review, vol. 22, no. 2, pp. 469–475, 2015. @article{Godwin2015a, The proportion of trials on which a target is presented (referred to as the target prevalence) during visual search influences the probability that the target will be detected. As prevalence increases, participants become biased toward reporting that the target is present. This bias results in an increase in detection rates for the target, coupled with an increased likelihood of making a false alarm. Previous work has demonstrated that, as prevalence increases, participants spend an increasing period of time searching on target-absent trials. The goal of the present study was to determine the information processing during the additional time spent searching on target-absent trials as prevalence increased. We recorded participants' eye movement behavior as they were engaged in low-prevalence (25% target-present trials), medium-prevalence (50%), or high-prevalence (75%) search. Increased prevalence primarily influenced search by increasing the time spent examining objects in the display, rather than by increasing the proportion of objects examined in each display. In addition, the additional time spent examining objects in high-prevalence target-absent trials was the result of revisiting objects. We discuss the implications of these results in relation to current models of search as well as ongoing efforts to alleviate the prevalence effect. |
Hayward J. Godwin; Tamaryn Menneer; Charlotte A. Riggs; Kyle R. Cave; Nick Donnelly Perceptual failures in the selection and identification of low-prevalence targets in relative prevalence visual search Journal Article In: Attention, Perception, and Psychophysics, vol. 77, no. 1, pp. 150–159, 2015. @article{Godwin2015b, Previous research has shown that during visual search tasts target prevalence (the proportion of trials in which a target appears) influences both the probability that a target will be detected, and the speed at which participants will quit searching and provide an 'absent' response. When prevelence is low (e.g., target presented on 2% of trials), participants are less likely to detect the target than when the prevelence is higher (e.g., 50% of trials). In the present set of experiments we examined perceptula faliures to detect low prevalence targets in visual search. We used a relative prevelence search task in order to be able to present and overall 50% target prevalence and thereby prevent the results being accounted for by early quitting behavour. Participants searched for two targets, one of which appeared on 45% of trials and another tha appeared on 5% of trials, leaving overall target prevalence at 50%. In the first experiment, participants searched for two dissimilar targets; in the second experiment, participants searched for two similar targets. Overall the results supported the notion that a reduction in prevalence primarily influenced perceptulal faliures of identification, rather than of selection. Thogether, these experiments add to a growing body of research exploring how and why observers fail to detect low prevalence targets, espically in real-world tasks in which some targets are more likely to appear than others. |
Ahu Gokce; Hermann J. Müller; Thomas Geyer Positional priming of visual pop-out search is supported by multiple spatial reference frames Journal Article In: Frontiers in Psychology, vol. 6, pp. 838, 2015. @article{Gokce2015, The present study investigates the representations(s) underlying positional priming of visual ‘pop-out' search (Maljkovic and Nakayama, 1996). Three search items (one target and two distractors) were presented at different locations, in invariant (Experiment 1) or random (Experiment 2) cross-trial sequences. By these manipulations it was possible to disentangle retinotopic, spatiotopic, and object-centered priming representations. Two forms of priming were tested: target location facilitation (i.e., faster reaction times – RTs– when the trial n target is presented at a trial n-1 target relative to n-1 blank location) and distractor location inhibition (i.e., slower RTs for n targets presented at n-1 distractor compared to n-1 blank locations). It was found that target locations were coded in positional short-term memory with reference to both spatiotopic and object-centered representations (Experiment 1 vs. 2). In contrast, distractor locations were maintained in an object-centered reference frame (Experiments 1 and 2). We put forward the idea that the uncertainty induced by the experiment manipulation (predictable versus random cross-trial item displacements) modulates the transition from object- to space-based representations in cross-trial memory for target positions. |
Ian Donovan; Sarit F. A. Szpiro; Marisa Carrasco Exogenous attention facilitates location transfer of perceptual learning Journal Article In: Journal of Vision, vol. 15, no. 10, pp. 1–16, 2015. @article{Donovan2015, Perceptual skills can be improved through practice on a perceptual task, even in adulthood. Visual perceptual learning is known to be mostly specific to the trained retinal location, which is considered as evidence of neural plasticity in retinotopic early visual cortex. Recent findings demonstrate that transfer of learning to untrained locations can occur under some specific training procedures. Here, we evaluated whether exogenous attention facilitates transfer of perceptual learning to untrained locations, both adjacent to the trained locations (Experiment 1) and distant from them (Experiment 2). The results reveal that attention facilitates transfer of perceptual learning to untrained locations in both experiments, and that this transfer occurs both within and across visual hemifields. These findings show that training with exogenous attention is a powerful regime that is able to overcome the major limitation of location specificity. |
Miguel P. Eckstein; Wade Schoonveld; Sheng Zhang; Stephen C. Mack; Emre Akbas Optimal and human eye movements to clustered low value cues to increase decision rewards during search Journal Article In: Vision Research, vol. 113, pp. 137–154, 2015. @article{Eckstein2015, Rewards have important influences on the motor planning of primates and the firing of neurons coding visual information and action. When eye movements to a target are differentially rewarded across locations, primates execute saccades towards the possible target location with the highest expected value, a product of sensory evidence and potentially earned reward (saccade to maximum expected value model, sMEV). Yet, in the natural world eye movements are not directly rewarded. Their role is to gather information to support subsequent rewarded search decisions and actions. Less is known about the effects of decision rewards on saccades. We show that when varying the decision rewards across cued locations following visual search, humans can plan their eye movements to increase decision rewards. Critically, we report a scenario for which five of seven tested humans do not preferentially deploy saccades to the possible target location with the highest reward, a strategy which is optimal when rewarding eye movements. Instead, these humans make saccades towards lower value but clustered locations when this strategy optimizes decision rewards consistent with the preferences of an ideal Bayesian reward searcher that takes into account the visibility of the target across eccentricities. The ideal reward searcher can be approximated with a sMEV model with pooling of rewards from spatially clustered locations. We also find observers with systematic departures from the optimal strategy and inter-observer variability of eye movement plans. These deviations often reflect multiplicity of fixation strategies that lead to near optimal decision rewards but, for some observers, it relates to suboptimal choices in eye movement planning. |
S. Gareth Edwards; Lisa J. Stephenson; Mario Dalmaso; Andrew P. Bayliss Social orienting in gaze leading: A mechanism for shared attention Journal Article In: Proceedings of the Royal Society B: Biological Sciences, vol. 282, no. 1812, pp. 1–8, 2015. @article{Edwards2015, Here, we report a novel social orienting response that occurs after viewing averted gaze. We show, in three experiments, that when a person looks from one location to an object, attention then shifts towards the face of an individual who has subsequently followed the person's gaze to that same object. That is, contrary to 'gaze following', attention instead orients in the opposite direction to observed gaze and towards the gazing face. The magnitude of attentional orienting towards a face that 'follows' the participant's gaze is also associated with self-reported autism-like traits. We propose that this gaze leading phenomenon implies the existence of a mechanism in the human social cognitive system for detecting when one's gaze has been followed, in order to establish 'shared attention' and maintain the ongoing interaction. |
Abdurahman S. Elkhetali; Ryan J. Vaden; Sean M. Pool; Kristina M. Visscher Early visual cortex reflects initiation and maintenance of task set Journal Article In: NeuroImage, vol. 107, pp. 277–288, 2015. @article{Elkhetali2015, The human brain is able to process information flexibly, depending on a person's task. The mechanisms underlying this ability to initiate and maintain a task set are not well understood, but they are important for understanding the flexibility of human behavior and developing therapies for disorders involving attention. Here we investigate the differential roles of early visual cortical areas in initiating and maintaining a task set.Using functional Magnetic Resonance Imaging (fMRI), we characterized three different components of task set-related, but trial-independent activity in retinotopically mapped areas of early visual cortex, while human participants performed attention demanding visual or auditory tasks. These trial-independent effects reflected: (1) maintenance of attention over a long duration, (2) orienting to a cue, and (3) initiation of a task set. Participants performed tasks that differed in the modality of stimulus to be attended (auditory or visual) and in whether there was a simultaneous distractor (auditory only, visual only, or simultaneous auditory and visual). We found that patterns of trial-independent activity in early visual areas (V1, V2, V3, hV4) depend on attended modality, but not on stimuli. Further, different early visual areas play distinct roles in the initiation of a task set. In addition, activity associated with maintaining a task set tracks with a participant's behavior. These results show that trial-independent activity in early visual cortex reflects initiation and maintenance of a person's task set. |
Phillip C. F Law; Bryan K. Paton; Jacqueline A. Riddiford; Caroline T. Gurvich; Trung T. Ngo; Steven M. Miller No relationship between binocular rivalry rate and eye-movement profiles in healthy individuals: A Bayes factor analysis Journal Article In: Perception, vol. 44, no. 5, pp. 643–661, 2015. @article{Law2015, Binocular rivalry (BR) is an intriguing phenomenon in which conflicting images are presented, one to each eye, resulting in perceptual alternations between each image. The rate of BR has been proposed as a potential endophenotype for bipolar disorder because (a) it is well established that this highly heritable psychiatric condition is associated with slower BR rate than in controls, and (b) an individual's BR rate is approximately 50% genetically determined. However, eye movements (EMs) could potentially account for the slow BR trait given EM anomalies are observed in psychiatric populations, and there has been report of an association between saccadic rate and BR rate in healthy individuals. Here, we sought to assess the relationship between BR rate and EMs in healthy individuals (N ¼ 40, mean age ¼ 34.4) using separate BR and EM tasks, with the latter measuring saccades during anticipatory, antisaccade, prosaccade, self-paced, free-viewing, and smooth-pursuit tasks. No correlation was found between BR rate and any EM measure for any BR task (p >.01) with substantial evidence favoring this lack of association (BF01 > 3). This finding is in contrast to previous data and has important implications for using BR rate as an endophenotype. If replicated in clinical psychiatric populations, EM interpretations of the slow BR trait can be excluded. |
James Lee; Jessica Manousakis; Joanne Fielding; Clare Anderson Alcohol and sleep restriction combined reduces vigilant attention, whereas sleep restriction alone enhances distractibility Journal Article In: Sleep, vol. 38, no. 5, pp. 765–775, 2015. @article{Lee2015a, STUDY OBJECTIVES: Alcohol and sleep loss are leading causes of motor vehicle crashes, whereby attention failure is a core causal factor. Despite a plethora of data describing the effect of alcohol and sleep loss on vigilant attention, little is known about their effect on voluntary and involuntary visual attention processes. DESIGN: Repeated-measures, counterbalanced design. SETTING: Controlled laboratory setting. PARTICIPANTS: Sixteen young (18-27 y; M = 21.90 ± 0.60 y) healthy males. INTERVENTIONS: Participants completed an attention test battery during the afternoon (13:00-14:00) under four counterbalanced conditions: (1) baseline; (2) alcohol (0.05% breath alcohol concentration); (3) sleep restriction (02:00-07:00); and (4) alcohol/sleep restriction combined. This test battery included a Psychomotor Vigilance Task (PVT) as a measure of vigilant attention, and two ocular motor tasks-visually guided and antisaccade-to measure the involuntary and voluntary allocation of visual attention. MEASUREMENTS AND RESULTS: Only the combined condition led to reductions in vigilant attention characterized by slower mean reaction time, fastest 10% responses, and increased number of lapses (P < 0.05) on the PVT. In addition, the combined condition led to a slowing in the voluntary allocation of attention as reflected by increased antisaccade latencies (P < 0.05). Sleep restriction alone however increased both antisaccade inhibitory errors [45.8% errors versus < 28.4% all others; P < 0.001] and the involuntary allocation of attention, as reflected by faster visually guided latencies (177.7 msec versus > 185.0 msec all others) to a peripheral target (P < 0.05). CONCLUSIONS: Our data reveal specific signatures for sleep related attention failure: the voluntary allocation of attention is impaired, whereas the involuntary allocation of attention is enhanced. This provides key evidence for the role of distraction in attention failure during sleep loss. |
Chantal L. Lemieux; Charles A. Collin; Elizabeth A. Nelson Modulations of eye movement patterns by spatial filtering during the learning and testing phases of an old/new face recognition task Journal Article In: Attention, Perception, and Psychophysics, vol. 77, no. 2, pp. 536–550, 2015. @article{Lemieux2015, In two experiments, we examined the effects of varying the spatial frequency (SF) content of face images on eye movements during the learning and testing phases of an old/new recognition task. At both learning and testing, participants were presented with face stimuli band-pass filtered to 11 different SF bands, as well as an unfiltered baseline condition. We found that eye movements varied significantly as a function of SF. Specifically, the frequency of transitions between facial features showed a band-pass pattern, with more transitions for middle-band faces (a parts per thousand 5-20 cycles/face) than for low-band (a parts per thousand < 5 cpf) or high-band (a parts per thousand > 20 cpf) ones. These findings were similar for the learning and testing phases. The distributions of transitions across facial features were similar for the middle-band, high-band, and unfiltered faces, showing a concentration on the eyes and mouth; conversely, low-band faces elicited mostly transitions involving the nose and nasion. The eye movement patterns elicited by low, middle, and high bands are similar to those previous researchers have suggested reflect holistic, configural, and featural processing, respectively. More generally, our results are compatible with the hypotheses that eye movements are functional, and that the visual system makes flexible use of visuospatial information in face processing. Finally, our finding that only middle spatial frequencies yielded the same number and distribution of fixations as unfiltered faces adds more evidence to the idea that these frequencies are especially important for face recognition, and reveals a possible mediator for the superior performance that they elicit. |
Karolina M. Lempert; Yu Lin Chen; Stephen M. Fleming Relating pupil dilation and metacognitive confidence during auditory decision-making Journal Article In: PLoS ONE, vol. 10, no. 5, pp. e0126588, 2015. @article{Lempert2015, The sources of evidence contributing to metacognitive assessments of confidence in decision-making remain unclear. Previous research has shown that pupil dilation is related to the signaling of uncertainty in a variety of decision tasks. Here we ask whether pupil dilation is also related to metacognitive estimates of confidence. Specifically, we measure the relationship between pupil dilation and confidence during an auditory decision task using a general linear model approach to take into account delays in the pupillary response. We found that pupil dilation responses track the inverse of confidence before but not after a decision is made, even when controlling for stimulus difficulty. In support of an additional post-decisional contribution to the accuracy of confidence judgments, we found that participants with better metacognitive ability - that is, more accurate appraisal of their own decisions - showed a tighter relationship between post-decisional pupil dilation and confidence. Together our findings show that a physiological index of uncertainty, pupil dilation, predicts both confidence and metacognitive accuracy for auditory decisions. |
Karolina M. Lempert; Elizabeth A. Phelps; Paul W. Glimcher; Elizabeth A. Phelps Emotional arousal and discount rate in intertemporal choice are reference-dependent Journal Article In: Journal of Experimental Psychology: General, vol. 144, no. 2, pp. 366–373, 2015. @article{Lempert2015a, Many decisions involve weighing immediate gratification against future consequences. In such intertemporal choices, people often choose smaller, immediate rewards over larger delayed rewards. It has been proposed that emotional responses to immediate rewards lead us to choose them at our long-term expense. Here we utilize an objective measure of emotional arousal – pupil dilation – to examine the role of emotion in these decisions. We show that emotional arousal responses, as well as choices, in intertemporal choice tasks are reference-dependent and reflect the decision-maker's recent history of offers. Arousal increases when less predictable rewards are better than expected, whether those rewards are immediate or delayed. Furthermore, when immediate rewards are less predictable than delayed rewards, participants tend to be patient. When delayed rewards are less predictable, immediate rewards are preferred. Our findings suggest that we can encourage people to be more patient by changing the context in which intertemporal choices are made. |
Carly J. Leonard; Angela Balestreri; Steven J. Luck Interactions between space-based and feature-based attention Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 41, no. 1, pp. 11–16, 2015. @article{Leonard2015, Although early research suggested that attention to nonspatial features (i.e., red) was confined to stimuli appearing at an attended spatial location, more recent research has emphasized the global nature of feature-based attention. For example, a distractor sharing a target feature may capture attention even if it occurs at a task-irrelevant location. Such findings have been used to argue that feature-based attention operates independently of spatial attention. However, feature-based attention may nonetheless interact with spatial attention, yielding larger feature-based effects at attended locations than at unattended locations. The present study tested this possibility. In 2 experiments, participants viewed a rapid serial visual presentation (RSVP) stream and identified a target letter defined by its color. Target-colored distractors were presented at various task-irrelevant locations during the RSVP stream. We found that feature-driven attentional capture effects were largest when the target-colored distractor was closer to the attended location. These results demonstrate that spatial attention modulates the strength of feature-based attention capture, calling into question the prior evidence that feature-based attention operates in a global manner that is independent of spatial attention. |
Clément Letesson; Stéphane Grade; Martin G. Edwards Different but complementary roles of action and gaze in action observation priming: Insights from eye-and motion-tracking measures Journal Article In: Frontiers in Psychology, vol. 6, pp. 569, 2015. @article{Letesson2015, Action priming following action observation is thought to be caused by the observed action kinematics being represented in the same brain areas as those used for action execution. But, action priming can also be explained by shared goal representations, with compatibility between observation of the agent's gaze and the intended action of the observer. To assess the contribution of action kinematics and eye-gaze cues in the prediction of an agent's action goal and action priming, participants observed actions where the availability of both cues was manipulated. Action observation was followed by action execution, and the congruency between the target of the agent's and observer's actions, and the congruency between the observed and executed action spatial location were manipulated. Eye movements were recorded during the observation phase, and the action priming was assessed using motion analysis. The results showed that the observation of gaze information influenced the observer's prediction speed to attend to the target, and that observation of action kinematic information influenced the accuracy of these predictions. Motion analysis results showed that observed action cues alone primed both spatial incongruent and object congruent actions, consistent with the idea that the prime effect was driven by similarity between goals and kinematics. The observation of action and eye-gaze cues together induced a prime effect complementarily sensitive to object and spatial congruency. While observation of the agent's action kinematics triggered an object-centered and kinematic-centered action representation, independently, the complementary observation of eye-gaze triggered a more fine-grained representation illustrating a specification of action kinematics toward the selected goal. Even though both cues differentially contributed to action priming, their complementary integration led to a more refined pattern of action priming. |
Heiko Lex; Kai Essig; Andreas Knoblauch; Thomas Schack Cognitive representations and cognitive processing of team-specific tactics in soccer Journal Article In: PLoS ONE, vol. 10, no. 2, pp. e0118219, 2015. @article{Lex2015, Two core elements for the coordination of different actions in sport are tactical information and knowledge about tactical situations. The current study describes two experiments to learn about the memory structure and the cognitive processing of tactical information. Experiment 1 investigated the storage and structuring of team-specific tactics in humans' long-term memory with regard to different expertise levels. Experiment 2 investigated tactical decision-making skills and the corresponding gaze behavior, in presenting participants the identical match situations in a reaction time task. The results showed that more experienced soccer players, in contrast to less experienced soccer players, possess a functionally organized cognitive representation of team-specific tactics in soccer. Moreover, the more experienced soccer players reacted faster in tactical decisions, because they needed less fixations of similar duration as compared to less experienced soccer players. Combined, these experiments offer evidence that a functionally organized memory structure leads to a reaction time and a perceptual advantage in tactical decision-making in soccer. The discussion emphasizes theoretical and applied implications of the current results of the study. |
Shinichiro Kira; Tianming Yang; Michael N. Shadlen A neural implementation of Wald's Sequential Probability Ratio Test Journal Article In: Neuron, vol. 85, no. 4, pp. 861–873, 2015. @article{Kira2015, Difficult decisions often require evaluation of samples of evidence acquired sequentially. A sensible strategy is to accumulate evidence, weighted by its reliability, until sufficient support is attained. An optimal statistical approach would accumulate evidence in units of logarithms of likelihood ratios (logLR) to a desired level. Studies of perceptual decisions suggest that the brain approximates an analogous procedure, but a direct test of accumulation, in units of logLR, to a threshold in units of cumulative logLR is lacking. We trained rhesus monkeys to make decisions based on a sequence of evanescent, visual cues assigned different logLR, hence different reliability. Firing rates of neurons in the lateral intraparietal area (LIP) reflected the accumulation of logLR and reached a stereotyped level before the monkeys committed to a decision. The monkeys' choices and reaction times, including their variability, were explained by LIP activity in the context of accumulation of logLR to a threshold. |
Mathias Klinghammer; Gunnar Blohm; Katja Fiehler Contextual factors determine the use of allocentric information for reaching in a naturalistic scene Journal Article In: Journal of Vision, vol. 15, no. 13, pp. 1–13, 2015. @article{Klinghammer2015, Numerous studies have demonstrated that humans incorporate allocentric information when reaching toward visual targets. So far, it is unclear how this information is integrated into the movement plan when multiple allocentric cues are available. In this study we investigated whether and how the extent of spatial changes and the task relevance of allocentric cues influence reach behavior. To this end, we conducted two experiments where we presented participants three- dimensional–rendered images of a naturalistic breakfast scene on a computer screen. The breakfast scene included multiple objects (allocentric cues) with a subset of objects functioning as potential reach targets (i.e., they were task-relevant). Participants freely viewed the scene and after a short delay, the scene reappeared with one object missing (target) and other objects being shifted left- or rightwards. Afterwards, participants were asked to reach toward the target position on a gray screen while fixating the screen center. We found systematic deviations of reach endpoints in the direction of object shifts which varied with the number of objects shifted, but only if these objects served as potential reach targets. Our results suggest that the integration of allocentric information into the reach plan is determined by contextual factors, in particular by the extent of spatial cue changes and the task-relevance of allocentric cues. |
Niels A. Kloosterman; Thomas Meindertsma; Arjan Hillebrand; Bob W. Dijk; Victor A. F. Lamme; Tobias H. Donner Top-down modulation in human visual cortex predicts the stability of a perceptual illusion Journal Article In: Journal of Neurophysiology, vol. 113, no. 4, pp. 1063–1076, 2015. @article{Kloosterman2015, Conscious perception sometimes fluctuates strongly, even when the sensory input is constant. For example, in motion-induced blindness (MIB), a salient visual target surrounded by a moving pattern suddenly disappears from perception, only to reappear after some variable time. Whereas such changes of perception result from fluctuations of neural activity, mounting evidence suggests that the perceptual changes, in turn, may also cause modulations of activity in several brain areas, including visual cortex. In this study, we asked whether these latter modulations might affect the subsequent dynamics of perception. We used magnetoencephalography (MEG) to measure modulations in cortical population activity during MIB. We observed a transient, retinotopically widespread modulation of beta (12-30 Hz)-frequency power over visual cortex that was closely linked to the time of subjects' behavioral report of the target disappearance. This beta modulation was a top-down signal, decoupled from both the physical stimulus properties and the motor response but contingent on the behavioral relevance of the perceptual change. Critically, the modulation amplitude predicted the duration of the subsequent target disappearance. We propose that the transformation of the perceptual change into a report triggers a top-down mechanism that stabilizes the newly selected perceptual interpretation. |
Niels A. Kloosterman; Thomas Meindertsma; Anouk Mariette Loon; Victor A. F. Lamme; Yoram S. Bonneh; Tobias H. Donner Pupil size tracks perceptual content and surprise Journal Article In: European Journal of Neuroscience, vol. 41, no. 8, pp. 1068–1078, 2015. @article{Kloosterman2015a, Changes in pupil size at constant light levels reflect the activity of neuromodulatory brainstem centers that control global brain state. These endogenously driven pupil dynamics can be synchronized with cognitive acts. For example, the pupil dilates during the spontaneous switches of perception of a constant sensory input in bistable perceptual illusions. It is unknown whether this pupil dilation only indicates the occurrence of perceptual switches, or also their content. Here, we measured pupil diameter in human subjects reporting the subjective disappearance and re-appearance of a physically constant visual target surrounded by a moving pattern ('motion-induced blindness' illusion). We show that the pupil dilates during the perceptual switches in the illusion and a stimulus-evoked 'replay' of that illusion. Critically, the switch-related pupil dilation encodes perceptual content, with larger amplitude for disappearance than re-appearance. This difference in pupil response amplitude enables prediction of the type of report (disappearance vs. re-appearance) on individual switches (receiver-operating characteristic: 61%). The amplitude difference is independent of the relative durations of target-visible and target-invisible intervals and subjects' overt behavioral report of the perceptual switches. Further, we show that pupil dilation during the replay also scales with the level of surprise about the timing of switches, but there is no evidence for an interaction between the effects of surprise and perceptual content on the pupil response. Taken together, our results suggest that pupil-linked brain systems track both the content of, and surprise about, perceptual events. |
N. Kloth; Lisa N. Jefferies; Gillian Rhodes Gaze direction affects the magnitude of face identity aftereffects Journal Article In: Journal of Vision, vol. 15, no. 2, pp. 1–12, 2015. @article{Kloth2015, The face perception system partly owes its efficiency to adaptive mechanisms that constantly recalibrate face coding to our current diet of faces. Moreover, faces that are better attended produce more adaptation. Here, we investigated whether the social cues conveyed by a face can influence the amount of adaptation that face induces. We compared the magnitude of face identity aftereffects induced by adaptors with direct and averted gazes.We reasoned that faces conveying direct gaze may be more engaging and better attended and thus produce larger aftereffects than those with averted gaze. Using an adaptation duration of 5 s, we found that aftereffects for adaptors with direct and averted gazes did not differ (Experiment 1). However, when processing demands were increased by reducing adaptation duration to 1 s, we found that gaze direction did affect the magnitude of the aftereffect, but in an unexpected direction: Aftereffects were larger for adaptors with averted rather than direct gaze (Experiment 2). Eye tracking revealed that differences in looking time to the faces between the two gaze directions could not account for these findings. Subsequent ratings of the stimuli (Experiment 3) showed that adaptors with averted gaze were actually perceived as more expressive and interesting than adaptors with direct gaze. Therefore it appears that the averted-gaze faces were more engaging and better attended, leading to larger aftereffects. Overall, our results suggest that naturally occurring facial signals can modulate the adaptive impact a face exerts on our perceptual system. Specifically, the faces that we perceive as most interesting also appear to calibrate the organization of our perceptual system most strongly. |
Peter J. Kohler; Patrick Cavanagh; Peter U. Tse Motion-induced position shifts are influenced by global motion, but dominated by component motion Journal Article In: Vision Research, vol. 110, pp. 93–99, 2015. @article{Kohler2015, Object motion and position have long been thought to involve largely independent visual computations. However, the motion-induced position shift (Eagleman & Sejnowski, 2007) shows that the perceived position of a briefly presented static object can be influenced by nearby moving contours. Here we combine a particularly strong example of this illusion with a bistable global motion stimulus to compare the relative effects of global and component motion on the shift in perceived position. We used a horizontally oscillating diamond (Lorenceau & Shiffrar, 1992) that produces two possible global directions (left and right when fully visible versus up and down when vertices are occluded by vertical bars) as well as the oblique component motion orthogonal to each contour. To measure the motion-induced shift we flashed a test dot on the contour as the diamond reversed direction (Cavanagh & Anstis, 2013). Although the global motion had a highly significant influence on the direction and size of the motion-induced position shift, the perceived displacement of the probe was closer to the direction of the component motion. These findings show that while global motion can clearly influence position shifts, it is the component motion that dominates in setting the position shift. This is true even though the perceived motion is in the global direction and the component motion is not consciously experienced. This suggests that perceived position is influenced by motion signals that arise earlier in time or earlier in processing compared to the stage at which the conscious experience of motion is determined. |
Naoko Koide; Takatomi Kubo; Satoshi Nishida; Tomohiro Shibata; Kazushi Ikeda Art expertise reduces influence of visual salience on fixation in viewing abstract- paintings Journal Article In: PLoS ONE, vol. 10, no. 2, pp. e0117696, 2015. @article{Koide2015, When viewing a painting, artists perceive more information from the painting on the basis of their experience and knowledge than art novices do. This difference can be reflected in eye scan paths during viewing of paintings. Distributions of scan paths of artists are different from those of novices even when the paintings contain no figurative object (i.e. abstract paintings). There are two possible explanations for this difference of scan paths. One is that artists have high sensitivity to high-level features such as textures and composition of colors and therefore their fixations are more driven by such features compared with novices. The other is that fixations of artists are more attracted by salient features than those of novices and the fixations are driven by low-level features. To test these, wemeasured eye fixations of artists and novices during the free viewing of various abstract paintings and compared the distribution of their fixations for each painting with a topological attentional map that quantifies the conspicuity of low-level features in the painting (i.e. saliency map).We found that the fixation distribution of artists was more distinguishable from the saliency map than that of novices. This difference indicates that fixations of artists are less driven by low-level features than those of novices. Our result suggests that artists may extract visual informa- tion from paintings based on high-level features. This ability of artists may be associated with artists' deep aesthetic appreciation of paintings. |
Moritz Köster; Marco Rüth; Kai Christoph Hamborg; Kai Kaspar Effects of personalized banner ads on visual attention and recognition memory Journal Article In: Applied Cognitive Psychology, vol. 29, no. 2, pp. 181–192, 2015. @article{Koester2015, Internet companies collect a vast amount of data about their users in order to personalize banner ads. However, very little is known about the effects of personalized banners on attention and memory. In the present study, 48 subjects performed search tasks on web pages containing personalized or nonpersonalized banners. Overt attention was measured by an eye-tracker, and recognition of banner and task-relevant information was subsequently examined. The entropy of fixations served as a measure for the overall exploration of web pages. Results confirm the hypotheses that personalization enhances recognition for the content of banners while the effect on attention was weaker and partially nonsignificant. In contrast, overall exploration of web pages and recognition of task-relevant information was not influenced. The temporal course of fixations revealed that visual exploration of banners typically proceeds from the picture to the logo and finally to the slogan. We discuss theoretical and practical implications. |
Christopher K. Kovach; Ralph Adolphs Investigating attention in complex visual search Journal Article In: Vision Research, vol. 116, pp. 127–141, 2015. @article{Kovach2015, How we attend to and search for objects in the real world is influenced by a host of low-level and higher-level factors whose interactions are poorly understood. The vast majority of studies approach this issue by experimentally controlling one or two factors in isolation, often under conditions with limited ecological validity. We present a comprehensive regression framework, together with a matlab-implemented toolbox, which allows concurrent factors influencing saccade targeting to be more clearly distinguished. Based on the idea of gaze selection as a point process, the framework allows each putative factor to be modeled as a covariate in a generalized linear model, and its significance to be evaluated with model-based hypothesis testing. We apply this framework to visual search for faces as an example and demonstrate its power in detecting effects of eccentricity, inversion, task congruency, emotional expression, and serial fixation order on the targeting of gaze. Among other things, we find evidence for multiple goal-related and goal-independent processes that operate with distinct visuotopy and time course. |
Sören Krach; Inge Kamp-Becker; Wolfgang Einhäuser; Jens Sommer; Stefan Frässle; Andreas Jansen; Lena Rademacher; Laura Müller-Pinzler; Valeria Gazzola; Frieder M. Paulus Evidence from pupillometry and fMRI indicates reduced neural response during vicarious social pain but not physical pain in autism Journal Article In: Human Brain Mapping, vol. 36, no. 11, pp. 4730–4744, 2015. @article{Krach2015, Autism spectrum disorder (ASD) is characterized by substantial social deficits. The notion that dysfunctions in neural circuits involved in sharing another's affect explain these deficits is appealing, but has received only modest experimental support. Here we evaluated a complex paradigm on the vicarious social pain of embarrassment to probe social deficits in ASD as to whether it is more potent than paradigms currently in use. To do so we acquired pupillometry and fMRI in young adults with ASD and matched healthy controls. During a simple vicarious physical pain task no differences emerged between groups in behavior, pupillometry, and neural activation of the anterior insula (AIC) and anterior cingulate cortex (ACC). In contrast, processing complex vicarious social pain yielded reduced responses in ASD on all physiological measures of sharing another's affect. The reduced activity within the AIC was thereby explained by the severity of autistic symptoms in the social and affective domain. Additionally, behavioral responses lacked correspondence with the anterior cingulate and anterior insula cortex activity found in controls. Instead, behavioral responses in ASD were associated with hippocampal activity. The observed dissociation echoes the clinical observations that deficits in ASD are most pronounced in complex social situations and simple tasks may not probe the dysfunctions in neural pathways involved in sharing affect. Our results are highly relevant because individuals with ASD may have preserved abilities to share another's physical pain but still have problems with the vicarious representation of more complex emotions that matter in life. |
Olave E. Krigolson; Cameron D. Hassall; Jason Satel; Raymond M. Klein The impact of cognitive load on reward evaluation Journal Article In: Brain Research, vol. 1627, pp. 225–232, 2015. @article{Krigolson2015, The neural systems that afford our ability to evaluate rewards and punishments are impacted by a variety of external factors. Here, we demonstrate that increased cognitive load reduces the functional efficacy of a reward processing system within the human medial–frontal cortex. In our paradigm, two groups of participants used performance feedback to estimate the exact duration of one second while electroencephalographic (EEG) data was recorded. Prior to performing the time estimation task, both groups were instructed to keep their eyes still and avoid blinking in line with well established EEG protocol. However, during performance of the time-estimation task, one of the two groups was provided with trial-to-trial-feedback about their performance on the time-estimation task and their eye movements to induce a higher level of cognitive load relative to participants in the other group who were solely provided with feedback about the accuracy of their temporal estimates. In line with previous work, we found that the higher level of cognitive load reduced the amplitude of the feedback-related negativity, a component of the human event-related brain potential associated with reward evaluation within the medial–frontal cortex. Importantly, our results provide further support that increased cognitive load reduces the functional efficacy of a neural system associated with reward processing. |
Günter Kugler; Bernard Marius Hart; Stefan Kohlbecher; Wolfgang Einhäuser; Erich Schneider Gaze in visual search is guided more efficiently by positive cues than by negative cues Journal Article In: PLoS ONE, vol. 10, no. 12, pp. e0145910, 2015. @article{Kugler2015, Visual search can be accelerated when properties of the target are known. Such knowledge allows the searcher to direct attention to items sharing these properties. Recent work indicates that information about properties of non-targets (i.e., negative cues) can also guide search. In the present study, we examine whether negative cues lead to different search behavior compared to positive cues. We asked observers to search for a target defined by a certain shape singleton (broken line among solid lines). Each line was embedded in a colored disk. In "positive cue" blocks, participants were informed about possible colors of the target item. In "negative cue" blocks, the participants were informed about colors that could not contain the target. Search displays were designed such that with both the positive and negative cues, the same number of items could potentially contain the broken line ("relevant items"). Thus, both cues were equally informative. We measured response times and eye movements. Participants exhibited longer response times when provided with negative cues compared to positive cues. Although negative cues did guide the eyes to relevant items, there were marked differences in eye movements. Negative cues resulted in smaller proportions of fixations on relevant items, longer duration of fixations and in higher rates of fixations per item as compared to positive cues. The effectiveness of both cue types, as measured by fixations on relevant items, increased over the course of each search. In sum, a negative color cue can guide attention to relevant items, but it is less efficient than a positive cue of the same informational value. |
Gustav Kuhn; Amber Pagano; Sumaya Maani; David Bunce Age-related decline in the reflexive component of overt gaze following Journal Article In: Quarterly Journal of Experimental Psychology, vol. 68, no. 6, pp. 1073–1081, 2015. @article{Kuhn2015, Previous research has found age-related declines in social perception tasks as well as the ability to engage in joint attention and orienting covert attention (i.e., absence of eye movements) in response to an eye gaze cue. We used an overt gaze following task to explore age differences in overt gaze following whilst people searched for a target. Participants were faster to detect targets appearing at the looked-at location, and although the gaze cue biased the direction in which saccades were executed, no age differences were found in overt gaze following. There were, however, age effects relating to involuntary eye movements. In the younger adults, anticipatory saccades were biased in the direction of the gaze cue, but this bias was not observed in the older group. Moreover, in the younger adults, saccades that followed the gaze were initiated more rapidly, illustrating the reflexive nature of gaze following. No such difference was observed in the older adults. Importantly, our results showed that whilst the general levels of gaze following were age invariant, there were age-related differences in the reflexive components of overt gaze following. |
Dave Kush; Jeffrey Lidz; Colin Phillips Relation-sensitive retrieval: Evidence from bound variable pronouns Journal Article In: Journal of Memory and Language, vol. 82, pp. 18–40, 2015. @article{Kush2015, Formal grammatical theories make extensive use of syntactic relations (e.g. c-command, Reinhart, 1983) in the description of constraints on antecedent-anaphor dependencies. Recent research has motivated a model of processing that exploits a cue-based retrieval mechanism in content-addressable memory (e.g. Lewis, Vasishth, & Van Dyke, 2006) in which item-to-item syntactic relations such as c-command are difficult to use as retrieval cues. As such, the c-command constraints of formal grammars are predicted to be poorly implemented by the retrieval mechanism. We tested whether memory access mechanisms are able to exploit relational information by investigating the processing of bound variable pronouns, a form of anaphoric dependency that imposes a c-command restriction on antecedent-pronoun relations. A quantificational NP (QP, e.g., no janitor) must c-command a pronoun in order to bind it. We contrasted the retrieval of QPs with the retrieval of referential NPs (e.g. the janitor), which can co-refer with a pronoun in the absence of c-command. In three off-line judgment studies and two eye-tracking studies, we show that referential NPs are easily accessed as antecedents, irrespective of whether they c-command the pronoun, but that quantificational NPs are accessed as antecedents only when they c-command the pronoun. These results are unexpected under theories that hold that retrieval exclusively uses a limited set of content features as retrieval cues. Our results suggest either that memory access mechanisms can make use of relational information as a guide for retrieval, or that the set of features that is used to encode syntactic relations in memory must be enriched. |
Kaitlin E. W. Laidlaw; Thariq A. Badiudeen; Mona J. H. Zhu; Alan Kingstone A fresh look at saccadic trajectories and task irrelevant stimuli: Social relevance matters Journal Article In: Vision Research, vol. 111, pp. 82–90, 2015. @article{Laidlaw2015, A distractor placed nearby a saccade target will cause interference during saccade planning and execution, and as a result will cause the saccade's trajectory to curve in a systematic way. It has been demonstrated that making a distractor more task-relevant, for example by increasing its similarity to the target, will increase the interference it imposes on the saccade and generate more deviant saccadic trajectories. Is the extent of a distractor's interference within the oculomotor system limited to its relevance to a particular current task, or can a distractor's general real-world meaning influence saccade trajectories even when it is made irrelevant within a task? Here, it is tested whether a task-irrelevant distractor can influence saccade trajectory if it depicts a stimulus that is normally socially relevant. Participants made saccades to a target object while also presented with a task-irrelevant (upright or inverted) face, or scrambled non-face equivalent. Results reveal that a distracting face creates greater deviation in saccade trajectory than does a non-face distractor, most notably at longer saccadic reaction times. These results demonstrate the sensitivity of processing that distractors are afforded by the oculomotor system, and support the view that distractor relevance beyond the task itself can also influence saccade planning and execution. |
Olympia Karampela; Linus Holm; Guy Madison In: Quarterly Journal of Experimental Psychology, vol. 68, no. 10, pp. 1965–1980, 2015. @article{Karampela2015, The origins of the ability to produce action at will at the hundreds of millisecond to second range remain poorly understood. A central issue is whether such timing is governed by one mechanism or by several, different mechanisms, possibly invoked by different effectors used to perform the timing task. If two effectors invoke similar timing mechanisms, then they should both produce similar variability increase with interval duration (inter- onset- interval) and thus adhere to Weber's law (increasing linearly with the duration of the interval to be timed). Additionally, if both effectors invoke the same timing mechanism, the variability of the effectors should be highly correlated across participants. To test these possibilities, we assessed the behavioral characteristics across fingers and eyes as effectors, and compared the timing variability between and within them as a function of the interval to be produced (inter-response interval). Sixty participants produced isochronous intervals from 524 to 1,431 ms with their fingers and their eyes. High correlations within each effector indicated consistent performance within participants. Consistent with a single mechanism, temporal variability in both fingers and eyes followed Weber's law, and significant correlations between eye and finger variability were found for several intervals. These results can neither support the single clock nor the multiple clock hypotheses but instead suggest a partially overlapping distributed timing system. |
Omid Kardan; Marc G. Berman; Grigori Yourganov; Joseph Schmidt; John M. Henderson Classifying mental states from eye movements during scene viewing Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 41, no. 6, pp. 1502–1514, 2015. @article{Kardan2015, How eye movements reflect underlying cognitive processes during scene viewing has been a topic of considerable theoretical interest. In this study, we used eye-movement features and their distributions over time to successfully classify mental states as indexed by the behavioral task performed by participants. We recorded eye movements from 72 participants performing 3 scene-viewing tasks: visual search, scene memorization, and aesthetic preference. To classify these tasks, we used statistical features (mean, standard deviation, and skewness) of fixation durations and saccade amplitudes, as well as the total number of fixations. The same set of visual stimuli was used in all tasks to exclude the possibility that different salient scene features influenced eye movements across tasks. All of the tested classification algorithms were successful in predicting the task within a single participant. The linear discriminant algorithm was also successful in predicting the task for each participant when the training data came from other participants, suggesting some generalizability across participants. The number of fixations contributed most to task classification; however, the remaining features and, in particular, their covariance provided important task-specific information. These results provide evidence on how participants perform different visual tasks. In the visual search task, for example, participants exhibited more variance and skewness in fixation durations and saccade amplitudes, but also showed heightened correlation between fixation durations and the variance in fixation durations. In summary, these results point to the possibility that eye-movement features and their distributional properties can be used to classify mental states both within and across individuals. |
Kai Kaspar; Ricardo Ramos Gameiro; Peter König Feeling good, searching the bad: Positive priming increases attention and memory for negative stimuli on webpages Journal Article In: Computers in Human Behavior, vol. 53, pp. 332–343, 2015. @article{Kaspar2015, Emotional impacts on attention arises in the form of externally and internally loaded forms. The former relates to the emotional valence of the sensory stimulus. The latter refers to the emotional state of the subject. We investigated their influence and interaction. Seventy-two subjects had been emotionally primed by a sequence of positive or negative images before they observed webpages of an online news portal. Each webpage contained positive and negative emotion-laden stimuli to be recalled in a memory test. We captured effects on overt attention, saccadic parameters, and explorative behavior. Furthermore, we related memory performance to characteristic gaze behavior. We found an attentional preference and a better memory performance for negative stimuli that was more pronounced after a positive mood induction. Importantly, increased attention correlated positively with recall performance on an individual level, but only after a positive mood induction. Moreover, the evaluation of the news-portal's hedonic quality and overall appeal, but not of usability, was affected by subjects' emotional states. We concluded that in contrast to previously reported mood-congruent preferences in young adults' attention, there are complementary effects of internally and externally loaded emotions with the tendency that positive priming increases attention and memory for negative stimuli. |
Kai Kaspar; Vanessa Krapp; Peter König Hand washing induces a clean slate effect in moral judgments: A pupillometry and eye-tracking study Journal Article In: Scientific Reports, vol. 5, pp. 10471, 2015. @article{Kaspar2015a, Physical cleansing is commonly understood to protect us against physical contamination. However, recent studies showed additional effects on moral judgments. Under the heading of the "Macbeth effect" direct links between bodily cleansing and one's own moral purity have been demonstrated. Here we investigate (1) how moral judgments develop over time and how they are altered by hand washing, (2) whether changes in moral judgments can be explained by altered information sampling from the environment, and (3) whether hand washing affects emotional arousal. Using a pre-post control group design, we found that morality ratings of morally good and bad scenes acquired more extreme values in the control group over time, an effect that was fully counteracted by intermediate hand washing. This result supports the notion of a clean slate effect by hand washing. Thereby, eye-tracking data did not uncover differences in eye movement behavior that may explain differences in moral judgments. Thus, the clean slate effect is not due to altered information sampling from the environment. Finally, compared to the control group, pupil diameter decreased after hand washing, thus demonstrating a direct physiological effect. The results shed light on the physiological mechanisms behind this type of embodiment phenomenon. |
Anna-Maria Kasparbauer; Natascha Merten; Désirée S. Aichert; Nicola Wöstmann; Thomas Meindl; Dan Rujescu; Ulrich Ettinger Association of COMT and SLC6A3 polymorphisms with impulsivity, response inhibition and brain function Journal Article In: Cortex, vol. 71, pp. 219–231, 2015. @article{Kasparbauer2015, Evidence of the genetic correlates of inhibitory control is scant. Two previously studied dopamine-related polymorphisms, COMT rs4680 and the SLC6A3 3' UTR 40-base-pair VNTR (rs28363170), have been associated with response inhibition, however with inconsistent findings. Here, we investigated the influence of these two polymorphisms in a large healthy adult sample (N = 515) on a response inhibition battery including the antisaccade, stop-signal, go/no-go and Stroop tasks as well as a psychometric measure of impulsivity (Barratt Impulsiveness Scale) (Experiment 1). Additionally, a subsample (N = 144) was studied while performing the go/no-go, stop-signal and antisaccade tasks in 3T fMRI (Experiment 2). In Experiment 1, we did not find any significant associations of COMT or SLC6A3 with inhibitory performance or impulsivity. In Experiment 2, no association of COMT with BOLD was found. However, there were consistent main effects of SLC6A3 genotype in all inhibitory contrasts: Homozygosity of the 10R allele was associated with greater fronto-striatal BOLD response than genotypes with at least one 9R allele. These findings are consistent with meta-analyses showing that the 10R allele is associated with reduced striatal dopamine transporter expression, which in animal studies has been found to lead to increased extracellular dopamine levels. Our study thus supports the involvement of striatal dopamine in the neural mechanisms of cognitive control, in particular response inhibition. |
Claire L. Kelly; Sandra I. Sünram-Lea; Trevor J. Crawford The role of motivation, glucose and self-control in the antisaccade task Journal Article In: PLoS ONE, vol. 10, no. 3, pp. e0122218, 2015. @article{Kelly2015, Research shows that self-control is resource limited and there is a gradual weakening in consecutive self-control task performance akin to muscle fatigue. A body of evidence suggests that the resource is glucose and consuming glucose reduces this effect. This study examined the effect of glucose on performance in the antisaccade task - which requires self-control through generating a voluntary eye movement away from a target - following self-control exertion in the Stroop task. The effects of motivation and individual differences in self-control were also explored. In a double-blind design, 67 young healthy adults received a 25g glucose or inert placebo drink. Glucose did not enhance antisaccade performance following self-control exertion in the Stroop task. Motivation however, predicted performance on the antisaccade task; more specifically high motivation ameliorated performance decrements observed after initial self-control exertion. In addition, individuals with high levels of self-control performed better on certain aspects of the antisaccade task after administration of a glucose drink. The results of this study suggest that the antisaccade task might be a powerful paradigm, which could be used as a more objective measure of self-control. Moreover, the results indicate that level of motivation and individual differences in self-control should be taken into account when investigating deficiencies in self-control following prior exertion. |
Shahabeddin Khalighy; Graham Green; Christoph Scheepers; Craig Whittet Quantifying the qualities of aesthetics in product design using eye-tracking technology Journal Article In: International Journal of Industrial Ergonomics, vol. 49, pp. 31–43, 2015. @article{Khalighy2015, This study provides a methodology to quantify the qualities of visual aesthetics in product design by applying eye-tracking technology. The output data of eye-tracking software, consisting of number, duration, and coordinate of eye fixations, are formulated using the fundamental constituent factors of beauty and attractiveness. This methodology has been developed by conducting three eye-tracking experiments and five experiments applying subjective measures which in total more than 300 participants attended. The results of these experiments contributed to the development of an aesthetic formula. The output of this formula was then compared with the declared preferences of a further 200 subjects. This comparison confirmed that the proposed methodology was capable of quantifying and predicting aesthetic preference by only monitoring eye behaviour. |
Aarlenne Zein Khan; Gunnar Blohm; Laure Pisella; Douglas P. Munoz Saccade execution suppresses discrimination at distractor locations rather than enhancing the saccade goal location Journal Article In: European Journal of Neuroscience, vol. 41, no. 12, pp. 1624–1634, 2015. @article{Khan2015, As we have limited processing abilities with respect to the plethora of visual information entering our brain, spatial selection mechanisms are crucial. These mechanisms result in both enhancing processing at a location of interest and in suppressing processing at other locations; together, they enable successful further processing of locations of interest. It has been suggested that saccade planning modulates these spatial selection mechanisms; however, the precise influence of saccades on the distribution of spatial resources underlying selection remains unclear. To this end, we compared discrimination performance at different locations (six) within a work space during different saccade tasks. We used visual discrimination performance as a behavioral measure of enhancement and suppression at the different locations. A total of 14 participants performed a dual discrimination/saccade countermanding task, which allowed us to specifically isolate the consequences of saccade execution. When a saccade was executed, discrimination performance at the cued location was never better than when fixation was maintained, suggesting that saccade execution did not enhance processing at a location more than knowing the likelihood of its appearance. However, discrimination was consistently lower at distractor (uncued) locations in all cases where a saccade was executed compared with when fixation was maintained. Based on these results, we suggest that saccade execution specifically suppresses distractor locations, whereas attention shifts (with or without an accompanying saccade) are involved in enhancing perceptual processing at the goal location. |