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2014 |
Diego Mendoza-Halliday; Santiago Torres; Julio C. Martinez-Trujillo Sharp emergence of feature-selective sustained activity along the dorsal visual pathway Journal Article In: Nature Neuroscience, vol. 17, no. 9, pp. 1255–1262, 2014. @article{MendozaHalliday2014, Sustained activity encoding visual working memory representations has been observed in several cortical areas of primates. Where along the visual pathways this activity emerges remains unknown. Here we show in macaques that sustained spiking activity encoding memorized visual motion directions is absent in direction-selective neurons in early visual area middle temporal (MT). However, it is robustly present immediately downstream, in multimodal association area medial superior temporal (MST), as well as and in the lateral prefrontal cortex (LPFC). This sharp emergence of sustained activity along the dorsal visual pathway suggests a functional boundary between early visual areas, which encode sensory inputs, and downstream association areas, which additionally encode mnemonic representations. Moreover, local field potential oscillations in MT encoded the memorized directions and, in the low frequencies, were phase-coherent with LPFC spikes. This suggests that LPFC sustained activity modulates synaptic activity in MT, a putative top-down mechanism by which memory signals influence stimulus processing in early visual cortex. |
Weston Pack; Stanley A. Klein; Thom Carney Bias corrected double judgment accuracy during spatial attention cueing: Unmasked stimuli with non-predictive and semi-predictive cues Journal Article In: Vision Research, vol. 105, pp. 213–225, 2014. @article{Pack2014, The present experiments indicate that in a 7-AFC double judgment accuracy task with unmasked stimuli, cue location response bias can be quantified and removed, revealing unbiased improvements in response accuracy for valid cues compared to invalid cues. By testing for cueing effects over a range of contrast levels with unmasked stimuli, changes in the psychometric function were examined and provide insight into the mechanisms of involuntary attention which might account for the observed cueing effects. Cue validity was varied between two separate experiments showing that non-predictive (14.3%) and moderately-predictive cues (50%) equally facilitate stimulus identification and localization during transient involuntary attention capture. Observers had improved accuracy at identifying both the location and the feature identity of target letters throughout a range of contrast levels, without any dependence on backward masking. There was a leftward shift of the psychometric function threshold with valid cued data and no slope reduction suggesting that any additive hypothesis based on spatial uncertainty reduction or perceptual enhancement is not a sufficient explanation for the observed cueing effects. The interdependence of the perceptual processes of stimulus discrimination and localization were also investigated by analyzing response contingencies, showing that observers were equally skilled at making identification and localization accuracy judgments with unmasked stimuli. |
Weston Pack; Stanley A. Klein; Thom Carney Bias-free double judgment accuracy during spatial attention cueing: Performance enhancement from voluntary and involuntary attention Journal Article In: Vision Research, vol. 105, pp. 204–212, 2014. @article{Pack2014a, Recent research has demonstrated that involuntary attention improves target identification accuracy for letters using non-predictive peripheral cues, helping to resolve some of the controversy over performance enhancement from involuntary attention. While various cueing studies have demonstrated that their reported cueing effects were not due to response bias to the cue, very few investigations have quantified the extent of any response bias or developed methods of removing bias from observed results in a double judgment accuracy task. We have devised a method to quantify and remove response bias to cued locations in a double judgment accuracy cueing task, revealing the true, unbiased performance enhancement from involuntary and voluntary attention. In a 7-alternative forced choice cueing task using backward masked stimuli to temporally constrain stimulus processing, non-predictive cueing increased target detection and discrimination at cued locations relative to uncued locations even after cue location bias had been corrected. |
Céline Paeye; Laurent Madelain Reinforcing saccadic amplitude variability in a visual search task Journal Article In: Journal of Vision, vol. 14, no. 13, pp. 1–18, 2014. @article{Paeye2014, Human observers often adopt rigid scanning strategies in visual search tasks, even though this may lead to suboptimal performance. Here we ask whether specific levels of saccadic amplitude variability may be induced in a visual search task using reinforcement learning. We designed a new gaze-contingent visual foraging task in which finding a target among distractors was made contingent upon specific saccadic amplitudes. When saccades of rare amplitudes led to displaying the target, the U values (measuring uncertainty) increased by 54.89% on average. They decreased by 41.21% when reinforcing frequent amplitudes. In a noncontingent control group no consistent change in variability occurred. A second experiment revealed that this learning transferred to conventional visual search trials. These results provide experimental support for the importance of reinforcement learning for saccadic amplitude variability in visual search. |
Adam Palanica; Roxane J. Itier Effects of peripheral eccentricity and head orientation on gaze discrimination Journal Article In: Visual Cognition, vol. 22, no. 9-10, pp. 1216–1232, 2014. @article{Palanica2014, Visual search tasks support a special role for direct gaze in human cognition, while classic gaze judgement tasks suggest the congruency between head orientation and gaze direction plays a central role in gaze perception. Moreover, whether gaze direction can be accurately discriminated in the periphery using covert attention is unknown. In the present study, individual faces in frontal and in deviated head orientations with a direct or an averted gaze were flashed for 150 ms across the visual field; participants focused on a centred fixation while judging the gaze direction. Gaze discrimination speed and accuracy varied with head orientation and eccentricity. The limit of accurate gaze discrimination was less than ±6° eccentricity. Response times suggested a processing facilitation for direct gaze in fovea, irrespective of head orientation, however, by ±3° eccentricity, head orientation started biasing gaze judgements, and this bias increased with eccentricity. Results also suggested a special processing of frontal heads with direct gaze in central vision, rather than a general congruency effect between eye and head cues. Thus, while both head and eye cues contribute to gaze discrimination, their role differs with eccentricity. |
Jinger Pan; Ming Yan; Jochen Laubrock; Hua Shu; Reinhold Kliegl Saccade-target selection of dyslexic children when reading Chinese Journal Article In: Vision Research, vol. 97, pp. 24–30, 2014. @article{Pan2014, This study investigates the eye movements of dyslexic children and their age-matched controls when reading Chinese. Dyslexic children exhibited more and longer fixations than age-matched control children, and an increase of word length resulted in a greater increase in the number of fixations and gaze durations for the dyslexic than for the control readers. The report focuses on the finding that there was a significant difference between the two groups in the fixation landing position as a function of word length in single-fixation cases, while there was no such difference in the initial fixation of multi-fixation cases. We also found that both groups had longer incoming saccade amplitudes while the launch sites were closer to the word in single fixation cases than in multi-fixation cases. Our results suggest that dyslexic children's inefficient lexical processing, in combination with the absence of orthographic word boundaries in Chinese, leads them to select saccade targets at the beginning of words conservatively. These findings provide further evidence for parafoveal word segmentation during reading of Chinese sentences. |
Xiaochuan Pan; Hongwei Fan; Kosuke Sawa; Ichiro Tsuda; Minoru Tsukada; Masamichi Sakagami Reward inference by primate prefrontal and striatal neurons Journal Article In: Journal of Neuroscience, vol. 34, no. 4, pp. 1380–1396, 2014. @article{Pan2014a, The brain contains multiple yet distinct systems involved in reward prediction. To understand the nature of these processes, we recorded single-unit activity from the lateral prefrontal cortex (LPFC) and the striatum in monkeys performing a reward inference task using an asymmetric reward schedule. We found that neurons both in the LPFC and in the striatum predicted reward values for stimuli that had been previously well experienced with set reward quantities in the asymmetric reward task. Importantly, these LPFC neurons could predict the reward value of a stimulus using transitive inference even when the monkeys had not yet learned the stimulus–reward association directly; whereas these striatal neurons did not show such an ability. Nevertheless, because there were two set amounts of reward (large and small), the selected striatal neurons were able to exclusively infer the reward value (e.g., large) of one novel stimulus from a pair after directly experiencing the alternative stimulus with the other reward value (e.g., small). Our results suggest that although neurons that predict reward value for old stimuli in the LPFC could also do so for new stimuli via transitive inference, those in the striatum could only predict reward for new stimuli via exclusive inference. Moreover, the striatum showed more complex functions than was surmised previously for model-free learning. |
Pierpaolo Pani; Tom Theys; Maria C. Romero; Peter Janssen Grasping execution and grasping observation activity of single neurons in the macaque anterior intraparietal area Journal Article In: Journal of Cognitive Neuroscience, vol. 26, no. 10, pp. 2342–2355, 2014. @article{Pani2014, Primates use vision to guide their actions in everyday life. Visually guided object grasping is known to rely on a network of cortical areas located in the parietal and premotor cortex. We recorded in the anterior intraparietal area (AIP), an area in the dorsal visual stream that is critical for object grasping and densely connected with the premotor cortex, while monkeys were grasping objects under visual guidance and during passive fixation of videos of grasping actions from the first-person perspective. All AIP neurons in this study responded during grasping execution in the light, that is, became more active after the hand had started to move toward the object and during grasping in the dark. More than half of these AIP neurons responded during the observation of a video of the same grasping actions on a display. Furthermore, these AIP neurons responded as strongly during passive fixation of movements of a hand on a scrambled background and to a lesser extent to a shape appearing within the visual field near the object. Therefore, AIP neurons responding during grasping execution also respond during passive observation of grasping actions and most of them even during passive observation of movements of a simple shape in the visual field. |
Sebastian Pannasch; Jens R. Helmert; Bruce C. Hansen; M. Adam; Lester C. Loschky Commonalities and differences in eye movement behavior when exploring aerial and terrestrial scenes Journal Article In: Cartography from Pole to Pole, pp. 421–430, 2014. @article{Pannasch2014, Eye movements can provide fast and precise insights into ongoing mechanisms of attention and information processing. In free exploration of natural scenes, it has repeatedly been shown that fixation durations increase over time, while saccade amplitudes decrease. This gaze behavior has been explained as a shift from ambient (global) to focal (local) processing as a means to efficiently understand different environments. In the current study, we analyzed eye movement behavior during the inspection of terrestrial and aerial views of real-world scene images. Our results show that the ambient to focal strategy is preserved across both perspectives. However, there are several perspective-related differences: For aerial views, the first fixation duration is prolonged, showing immediate processing difficulties. Furthermore, fixation durations and saccade amplitudes are longer throughout the overall time of scene exploration, showing continued difficulties that affect both processing of information and image scanning strategies. The temporal and spatial scanning of aerial views is also less similar between observers than for terrestrial scenes, suggesting an inability to use normal scanning patterns. The observed differences in eye movement behavior when inspecting terrestrial and aerial views suggest an increased processing effort for visual information that deviates from our everyday experiences. |
Muriel T. N. Panouillères; Ouazna Habchi; Peggy Gerardin; Roméo Salemme; Christian Urquizar; Alessandro Farnè; Denis Pélisson A role for the parietal cortex in sensorimotor adaptation of saccades Journal Article In: Cerebral Cortex, vol. 24, no. 2, pp. 304–314, 2014. @article{Panouilleres2014, Sensorimotor adaptation ensures movement accuracy despite continuously changing environment and body. Adaptation of saccadic eye movements is a classical model of sensorimotor adaptation. Beside the well-established role of the brainstem-cerebellum in the adaptation of reactive saccades (RSs), the cerebral cortex has been suggested to be involved in the adaptation of voluntary saccades (VSs). Here, we provide direct evidence for a causal involvement of the parietal cortex in saccadic adaptation. First, the posterior intraparietal sulcus (pIPS) was identified in each subject using functional magnetic resonance imaging (fMRI). Then, a saccadic adaptation paradigm was used to progressively reduce the amplitude of RSs and VSs, while single-pulse transcranial magnetic stimulation (spTMS) was applied over the right pIPS. The perturbations of pIPS resulted in impairment for the adaptation of VSs, selectively when spTMS was applied 60 ms after saccade onset. In contrast, the adaptation of RSs was facilitated by spTMS applied 90 ms after saccade initiation. The differential effect of spTMS relative to saccade types suggests a direct interference with pIPS activity for the VS adaptation and a remote interference with brainstem-cerebellum activity for the RS adaptation. These results support the hypothesis that the adaptation of VSs and RSs involves different neuronal substrates. |
T. C. Blanchard; Benjamin Y. Hayden Neurons in dorsal anterior cingulate cortex signal postdecisional variables in a foraging task Journal Article In: Journal of Neuroscience, vol. 34, no. 2, pp. 646–655, 2014. @article{Blanchard2014, The dorsal anterior cingulate cortex (dACC) is a key hub of the brain's executive control system. Although a great deal is known about its role in outcome monitoring and behavioral adjustment, whether and how it contributes to the decision process remain unclear. Some theories suggest that dACC neurons track decision variables (e.g., option values) that feed into choice processes and is thus "predecisional." Other theories suggest that dACC activity patterns differ qualitatively depending on the choice that is made and is thus "postdecisional." To compare these hypotheses, we examined responses of 124 dACC neurons in a simple foraging task in which monkeys accepted or rejected offers of delayed rewards. In this task, options that vary in benefit (reward size) and cost (delay) appear for 1 s; accepting the option provides the cued reward after the cued delay. To get at dACC neurons' contributions to decisions, we focused on responses around the time of choice, several seconds before the reward and the end of the trial. We found that dACC neurons signal the foregone value of the rejected option, a postdecisional variable. Neurons also signal the profitability (that is, the relative value) of the offer, but even these signals are qualitatively different on accept and reject decisions, meaning that they are also postdecisional. These results suggest that dACC can be placed late in the decision process and also support models that give it a regulatory role in decision, rather than serving as a site of comparison. |
Tommy C. Blanchard; Andreas Wilke; Benjamin Y. Hayden Hot-hand bias in rhesus monkeys Journal Article In: Journal of Experimental Psychology: Animal Behavior Processes, vol. 40, no. 3, pp. 280–286, 2014. @article{Blanchard2014a, Human decision-makers often exhibit the hot-hand phenomenon, a tendency to perceive positive serial autocorrelations in independent sequential events. The term is named after the observation that basketball fans and players tend to perceive streaks of high accuracy shooting when they are demonstrably absent. That is, both observing fans and participating players tend to hold the belief that a player's chance of hitting a shot are greater following a hit than following a miss. We hypothesize that this bias reflects a strong and stable tendency among primates (including humans) to perceive positive autocorrelations in temporal sequences, that this bias is an adaptation to clumpy foraging environments, and that it may even be ecologically rational. Several studies support this idea in humans, but a stronger test would be to determine whether nonhuman primates also exhibit a hot-hand bias. Here we report behavior of 3 monkeys performing a novel gambling task in which correlation between sequential gambles (i.e., temporal clumpiness) is systematically manipulated. We find that monkeys have better performance (meaning, more optimal behavior) for clumped (positively correlated) than for dispersed (negatively correlated) distributions. These results identify and quantify a new bias in monkeys' risky decisions, support accounts that specifically incorporate cognitive biases into risky choice, and support the suggestion that the hot-hand phenomenon is an evolutionary ancient bias. |
Tommy C. Blanchard; Lauren S. Wolfe; Ivo Vlaev; Joel S. Winston; Benjamin Y. Hayden Biases in preferences for sequences of outcomes in monkeys Journal Article In: Cognition, vol. 130, no. 3, pp. 289–299, 2014. @article{Blanchard2014b, Movies, vacations, and meals are all examples of events composed of a sequence of smaller events. How do we go from our evaluations of each scene in a movie to an evaluation of the sequence as a wholeα In theory, we should simply average the values of the individual events. In practice, however, we are biased towards sequences where each element tends to be better than the previous, where the last value is large, and we overweight the best (or worst) part of the sequence. To study how general these biases are we examined monkeys' preferences for sequences of rewards in a novel reward repeat task. Monkeys were first given a sequence of rewards and then chose between repeating the sequence or receiving a standard comparator sequence. We found that, like humans, monkeys overweight events that happen later in a sequence, so much so that adding a small reward to the end of a sequence can paradoxically reduce its value. Monkeys were also biased towards sequences with large peak values (the highest value in the sequence), but only following a working memory challenge, suggesting that this preference may be driven by memory limitations. These results demonstrate the cross-species nature of biases in preferences for sequences of outcomes. In addition, monkeys' consistent preference for sequences in which large values occur later challenges the generality of discounting models of intertemporal choice in animals. |
Julieanne Blum; Nicholas S. C. Price Reflexive tracking eye movements and motion perception: One or two neural populations? Journal Article In: Journal of Vision, vol. 14, no. 3, pp. 1–14, 2014. @article{Blum2014, Motion-sensitive neurons in the middle temporal (MT) and medial superior temporal (MST) areas perform the sensory analysis required for both motion perception and controlling smooth eye movements. The perceptual and oculomotor systems are characterized by high variability, even when responding to identical stimulus repetitions. If a single population of neurons performs the motion analysis driving perception and eye movements, errors in perception and action might show similar direction-dependent biases, or their variability might be correlated across trials. However, previous studies have produced conflicting reports of the presence of significant single-trial correlations between motion perception and the velocity of smooth pursuit, a volitional tracking eye movement. We studied ocular following, a reflexive tracking eye movement, simultaneously measuring eye movement direction and perceived direction of a moving random dot field. Oculomotor errors were largest for near-cardinal directions, providing the first evidence for cardinal repulsion in reflexive eye movements. Biases in perceptual and oculomotor errors were correlated across test directions, but not across single trials with the same direction. Based on the similar direction-dependent anisotropies in eye movements and perception, there is reason to believe that partially overlapping populations of sensory neurons underlie motion perception and oculomotor behaviors, with independent downstream sources of noise masking trial-by-trial correlations between perception and action. |
Hazel I. Blythe; Rebecca L. Johnson; Simon P. Liversedge; Keith Rayner Reading transposed text: effects of transposed letter distance and consonant-vowel status on eye movements Journal Article In: Attention, Perception, and Psychophysics, vol. 76, no. 8, pp. 2424–2440, 2014. @article{Blythe2014, Two experiments were conducted to investigate the flexibility of letter-position encoding in word identification during reading. In both experiments, two tasks were used. First, participants' eye movements were measured as they read sentences containing transposed letter (TL) strings. Second, participants were presented with the TL strings in isolation and were asked to discriminate them from nonwords. In Experiment 1, we manipulated the distance between transposed letters (ligament vs. liagment vs. limagent vs. lieamgnt). Reading/response times increased with the distance between TLs. In Experiment 2, we manipulated whether the TLs were consonants, vowels, or one of each (ssytem vs. faeture vs. fromat). Reading/response times showed that CV transpositions were the most disruptive. In both experiments, response accuracy was particularly poor for words presented in isolation when there was an intervening letter between TLs. These data show that processing across multiple fixations, and the presence of a meaningful sentence context, are important for flexible letter position encoding in lexical identification. |
Mark S. Bolding; Adrienne C. Lahti; David White; Claire Moore; Demet Gurler; Timothy J. Gawne; Paul D. Gamlin Vergence eye movements in patients with schizophrenia Journal Article In: Vision Research, vol. 102, pp. 64–70, 2014. @article{Bolding2014, Previous studies have shown that smooth pursuit eye movements are impaired in patients with schizophrenia. However, under normal viewing conditions, targets move not only in the frontoparallel plane but also in depth, and tracking them requires both smooth pursuit and vergence eye movements. Although previous studies in humans and non-human primates suggest that these two eye movement subsystems are relatively independent of one another, to our knowledge, there have been no prior studies of vergence tracking behavior in patients with schizophrenia. Therefore, we have investigated these eye movements in patients with schizophrenia and in healthy controls. We found that patients with schizophrenia exhibited substantially lower gains compared to healthy controls during vergence tracking at all tested speeds (e.g. 0.25. Hz vergence tracking mean gain of 0.59 vs. 0.86). Further, consistent with previous reports, patients with schizophrenia exhibited significantly lower gains than healthy controls during smooth pursuit at higher target speeds (e.g. 0.5. Hz smooth pursuit mean gain of 0.64 vs. 0.73). In addition, there was a modest (r≈0.5), but significant, correlation between smooth pursuit and vergence tracking performance in patients with schizophrenia. Our observations clearly demonstrate substantial vergence tracking deficits in patients with schizophrenia. In these patients, deficits for smooth pursuit and vergence tracking are partially correlated suggesting overlap in the central control of smooth pursuit and vergence eye movements. © 2014 Elsevier Ltd. |
Sabrina Boll; Matthias Gamer 5-HTTLPR modulates the recognition accuracy and exploration of emotional facial expressions Journal Article In: Frontiers in Behavioral Neuroscience, vol. 8, pp. 255, 2014. @article{Boll2014, Individual genetic differences in the serotonin transporter-linked polymorphic region (5-HTTLPR) have been associated with variations in the sensitivity to social and emotional cues as well as altered amygdala reactivity to facial expressions of emotion. Amygdala activation has further been shown to trigger gaze changes toward diagnostically relevant facial features. The current study examined whether altered socio-emotional reactivity in variants of the 5-HTTLPR promoter polymorphism reflects individual differences in attending to diagnostic features of facial expressions. For this purpose, visual exploration of emotional facial expressions was compared between a low (n = 39) and a high (n = 40) 5-HTT expressing group of healthy human volunteers in an eye tracking paradigm. Emotional faces were presented while manipulating the initial fixation such that saccadic changes toward the eyes and toward the mouth could be identified. We found that the low vs. the high 5-HTT group demonstrated greater accuracy with regard to emotion classifications, particularly when faces were presented for a longer duration. No group differences in gaze orientation toward diagnostic facial features could be observed. However, participants in the low 5-HTT group exhibited more and faster fixation changes for certain emotions when faces were presented for a longer duration and overall face fixation times were reduced for this genotype group. These results suggest that the 5-HTT gene influences social perception by modulating the general vigilance to social cues rather than selectively affecting the pre-attentive detection of diagnostic facial features. |
Paul J. Boon; Jan Theeuwes; Artem V. Belopolsky Updating visual-spatial working memory during object movement Journal Article In: Vision Research, vol. 94, pp. 51–57, 2014. @article{Boon2014, Working memory enables temporary maintenance and manipulation of information for immediate access by cognitive processes. The present study investigates how spatial information stored in working memory is updated during object movement. Participants had to remember a particular location on an object which, after a retention interval, started to move. The question was whether the memorized location was updated with the movement of the object or whether after object movement it remained represented in retinotopic coordinates. We used saccade trajectories to examine how memorized locations were represented. The results showed that immediately after the object stopped moving, there was both a retinotopic and an object-centered representation. However, 200. ms later, the activity at the retinotopic location decayed, making the memory representation fully object-centered. Our results suggest that memorized locations are updated from retinotopic to object-centered coordinates during, or shortly after object movement. |
Ali Borji; Laurent Itti Defending Yarbus: Eye movements reveal observers' task Journal Article In: Journal of Vision, vol. 14, no. 3, pp. 1–22, 2014. @article{Borji2014, In a very influential yet anecdotal illustration, Yarbus suggested that human eye-movement patterns are modulated top down by different task demands. While the hypothesis that it is possible to decode the observer's task from eye movements has received some support (e.g., Henderson, Shinkareva, Wang, Luke, & Olejarczyk, 2013; Iqbal & Bailey, 2004), Greene, Liu, and Wolfe (2012) argued against it by reporting a failure. In this study, we perform a more systematic investigation of this problem, probing a larger number of experimental factors than previously. Our main goal is to determine the informativeness of eye movements for task and mental state decoding. We perform two experiments. In the first experiment, we reanalyze the data from a previous study by Greene et al. (2012) and contrary to their conclusion, we report that it is possible to decode the observer's task from aggregate eye-movement features slightly but significantly above chance, using a Boosting classifier (34.12% correct vs. 25% chance level; binomial test, p ¼ 1.0722e – 04). In the second experiment, we repeat and extend Yarbus's original experiment by collecting eye movements of 21 observers viewing 15 natural scenes (including Yarbus's scene) under Yarbus's seven questions. We show that task decoding is possible, also moderately but significantly above chance (24.21% vs. 14.29% chance- level; binomial test, p ¼ 2.4535e – 06). We thus conclude that Yarbus's idea is supported by our data and continues to be an inspiration for future computational and experimental eye-movement research. From a broader perspective, we discuss techniques, features, limitations, societal and technological impacts, and future directions in task decoding from eye movements. |
Ali Borji; Daniel Parks; Laurent Itti Complementary effects of gaze direction and early saliency in guiding fixations during free viewing Journal Article In: Journal of Vision, vol. 14, no. 13, pp. 1–32, 2014. @article{Borji2014a, Gaze direction provides an important and ubiquitous communication channel in daily behavior and social interaction of humans and some animals. While several studies have addressed gaze direction in synthesized simple scenes, few have examined how it can bias observer attention and how it might interact with early saliency during free viewing of natural and realistic scenes. Experiment 1 used a controlled, staged setting in which an actor was asked to look at two different objects in turn, yielding two images that differed only by the actor's gaze direction, to causally assess the effects of actor gaze direction. Over all scenes, the median probability of following an actor's gaze direction was higher than the median probability of looking toward the single most salient location, and higher than chance. Experiment 2 confirmed these findings over a larger set of unconstrained scenes collected from the Web and containing people looking at objects and/or other people. To further compare the strength of saliency versus gaze direction cues, we computed gaze maps by drawing a cone in the direction of gaze of the actors present in the images. Gaze maps predicted observers' fixation locations significantly above chance, although below saliency. Finally, to gauge the relative importance of actor face and eye directions in guiding observer's fixations, in Experiment 3, observers were asked to guess the gaze direction from only an actor's face region (with the rest of the scene masked), in two conditions: actor eyes visible or masked. Median probability of guessing the true gaze direction within ±9° was significantly higher when eyes were visible, suggesting that the eyes contribute significantly to gaze estimation, in addition to face region. Our results highlight that gaze direction is a strong attentional cue in guiding eye movements, complementing low-level saliency cues, and derived from both face and eyes of actors in the scene. Thus gaze direction should be considered in constructing more predictive visual attention models in the future. |
Tobias Bormann; Sascha A. Wolfer; Wibke Hachmann; Wolf A. Lagrèze; Lars Konieczny An eye movement study on the role of the visual field defect in pure alexia Journal Article In: PLoS ONE, vol. 9, no. 7, pp. e100898, 2014. @article{Bormann2014, Pure alexia is a severe impairment of word reading which is usually accompanied by a right-sided visual field defect. Patients with pure alexia exhibit better preserved writing and a considerable word length effect, claimed to result from a serial letter processing strategy. Two experiments compared the eye movements of four patients with pure alexia to controls with simulated visual field defects (sVFD) when reading single words. Besides differences in response times and differential effects of word length on word reading in both groups, fixation durations and the occurrence of a serial, letter-by-letter fixation strategy were investigated. The analyses revealed quantitative and qualitative differences between pure alexic patients and unimpaired individuals reading with sVFD. The patients with pure alexia read words slower and exhibited more fixations. The serial, letter-by-letter fixation strategy was observed only in the patients but not in the controls with sVFD. It is argued that the VFD does not cause pure alexic reading. |
Sabine Born; Isaline Mottet; Dirk Kerzel Presaccadic perceptual facilitation effects depend on saccade execution: Evidence from the stop-signal paradigm Journal Article In: Journal of Vision, vol. 14, no. 3, pp. 1–10, 2014. @article{Born2014, Prior to the onset of a saccadic eye movement, perception is facilitated at the saccade target location. This has been attributed to a shift of attention. To test whether presaccadic attention shifts are strictly dependent on saccade execution, we examined whether they are found when observers are required to cancel the eye movement. We combined a dual task with the stop-signal paradigm: Subjects made saccades as quickly as possible to a cued location while discriminating a stimulus either at the saccade target or at the opposite location. A stop signal was presented on a subset of trials, asking subjects to cancel the eye movement. The delay of the stop signal was adjusted to yield successful inhibition of the saccade in 50% of trials. Results show similar perceptual facilitation at the saccade target for saccades with or without a stop signal, suggesting that presaccadic attention shifts are obligatory for all saccades. However, there was facilitation only when saccades were actually performed, not when observers successfully inhibited them. Thus, preparing an eye movement without subsequently executing it does not result in an attention shift. The results speak to a difference between saccade preparation and saccade programming. In light of the strong dependence on saccade execution, we discuss the functional role and causes of presaccadic attention shifts. |
Erin Berenbaum; Amy E. Latimer-Cheung Examining the link between framed physical activity ads and behavior among women Journal Article In: Journal of Sport and Exercise Psychology, vol. 36, no. 3, pp. 271–280, 2014. @article{Berenbaum2014, Gain-framed messages are more effective at promoting physical activity than loss-framed messages. However, the mechanism through which this effect occurs is unclear. The current experiment examined the effects of message framing on variables described in the communication behavior change model (McGuire, 1989), as well as the mediating effects of these variables on the message-frame-behavior relationship. Sixty low-to-moderately active women viewed 20 gain- or loss-framed ads and five control ads while their eye movements were recorded via eye tracking. The gain-framed ads attracted greater attention, ps < .05; produced more positive attitudes |
Jean-Baptiste Bernard; Aurélie Calabrèse; Eric Castet Role of syllable segmentation processes in peripheral word recognition Journal Article In: Vision Research, vol. 105, pp. 226–232, 2014. @article{Bernard2014, Previous studies of foveal visual word recognition provide evidence for a low-level syllable decomposition mechanism occurring during the recognition of a word. We investigated if such a decomposition mechanism also exists in peripheral word recognition. Single words were visually presented to subjects in the peripheral field using a 6° square gaze-contingent simulated central scotoma. In the first experiment, words were either unicolor or had their adjacent syllables segmented with two different colors (color/syllable congruent condition). Reaction times for correct word identification were measured for the two different conditions and for two different print sizes. Results show a significant decrease in reaction time for the color/syllable congruent condition compared with the unicolor condition. A second experiment suggests that this effect is specific to syllable decomposition and results from strategic, presumably involving attentional factors, rather than stimulus-driven control. |
Richard A. I. Bethlehem; Serge O. Dumoulin; Edwin S. Dalmaijer; Miranda Smit; Tos T. J. M. Berendschot; Tanja C. W. Nijboer; Stefan Van Der Stigchel Decreased fixation stability of the preferred retinal location in juvenile macular degeneration Journal Article In: PLoS ONE, vol. 9, no. 6, pp. e100171, 2014. @article{Bethlehem2014, Macular degeneration is the main cause for diminished visual acuity in the elderly. The juvenile form of macular degeneration has equally detrimental consequences on foveal vision. To compensate for loss of foveal vision most patients with macular degeneration adopt an eccentric preferred retinal location that takes over tasks normally performed by the healthy fovea. It is unclear however, whether the preferred retinal locus also develops properties typical for foveal vision. Here, we investigated whether the fixation characteristics of the preferred retinal locus resemble those of the healthy fovea. For this purpose, we used the fixation-offset paradigm and tracked eye-position using a high spatial and temporal resolution infrared eye-tracker. The fixation-offset paradigm measures release from fixation under different fixation conditions and has been shown useful to distinguish between foveal and non-foveal fixation. We measured eye-movements in nine healthy age-matched controls and five patients with juvenile macular degeneration. In addition, we performed a simulation with the same task in a group of five healthy controls. Our results show that the preferred retinal locus does not adopt a foveal type of fixation but instead drifts further away from its original fixation and has overall increased fixation instability. Furthermore, the fixation instability is most pronounced in low frequency eye-movements representing a slow drift from fixation. We argue that the increased fixation instability cannot be attributed to fixation under an unnatural angle. Instead, diminished visual acuity in the periphery causes reduced oculomotor control and results in increased fixation instability. |
Lysianne Beynel; Alan Chauvin; Nathalie Guyader; Sylvain Harquel; Thierry Bougerol; Christian Marendaz; David Szekely What saccadic eye movements tell us about TMS-induced neuromodulation of the DLPFC and mood changes: A pilot study in bipolar disorders Journal Article In: Frontiers in Integrative Neuroscience, vol. 8, pp. 65, 2014. @article{Beynel2014, The study assumed that the antisaccade (AS) task is a relevant psychophysical tool to assess (i) short-term neuromodulation of the dorsolateral prefrontal cortex (DLPFC) induced by intermittent theta burst stimulation (iTBS); and (ii) mood change occurring during the course of the treatment. Saccadic inhibition is known to strongly involve the DLPFC, whose neuromodulation with iTBS requires less stimulation time and lower stimulation intensity, as well as results in longer aftereffects than the conventional repetitive transcranial magnetic stimulation (rTMS). Active or sham iTBS was applied every day for 3 weeks over the left DLPFC of 12 drug-resistant bipolar depressed patients. To assess the iTBS-induced short-term neuromodulation, the saccadic task was performed just before (S1) and just after (S2) the iTBS session, the first day of each week. Mood was evaluated through Montgomery and Asberg Depression Rating Scale (MADRS) scores and the difference in scores between the beginning and the end of treatment was correlated with AS performance change between these two periods. As expected, only patients from the active group improved their performance from S1 to S2 and mood improvement was significantly correlated with AS performance improvement. In addition, the AS task also discriminated depressive bipolar patients from healthy control subjects. Therefore, the AS task could be a relevant and useful tool for clinicians to assess if the Transcranial magnetic stimulation (TMS)-induced short-term neuromodulation of the DLPFC occurs as well as a “trait vs. state” objective marker of depressive mood disorder. |
Daniel Bishop; Gustav Kuhn; Claire Maton Telling people where to look in a soccer-based decision task: A nomothetic approach Journal Article In: Journal of Eye Movement Research, vol. 7, no. 2, pp. 1–13, 2014. @article{Bishop2014, Research has shown that identifiable visual search patterns characterize skilled performance of anticipation and decision-making tasks in sport. However, to date, the use of experts' gaze patterns to entrain novices' performance has been confined to aiming activities. Accordingly, in a first experiment, 40 participants of varying soccer experience viewed static images of oncoming soccer players and attempted to predict the direction in which those players were about to move. Multiple regression analyses showed that the sole predictor of decision-making efficiency was the time taken to initiate a saccade to the ball. In a follow-up experiment, soccer novices undertook the same task as in Experiment 1. Two experimental groups were instructed to either look at the ball, or the player's head, as quickly as possible; a control group received no instructions. The experimental groups were fastest to make a saccade to the ball or head, respectively, but decision-making efficiency was equivalent across all three groups. The fallibility of a nomothetic approach to training eye movements is discussed. |
Marie-Josée Bisson; Walter J. B. Van Heuven; Kathy Conklin; Richard J. Tunney Processing of native and foreign language subtitles in films: An eye tracking study Journal Article In: Applied Psycholinguistics, vol. 35, no. 2, pp. 399–418, 2014. @article{Bisson2014, Foreign language (FL) films with subtitles are becoming increasingly popular, and many European countries use subtitling as a cheaper alternative to dubbing. However, the extent to which people process subtitles under different subtitling conditions remains unclear. In this study, participants watched part of a film under standard (FL soundtrack and native language subtitles), reversed (native language soundtrack and FL subtitles), or intralingual (FL soundtrack and FL subtitles) subtitling conditions while their eye movements were recorded. The results revealed that participants read the subtitles irrespective of the subtitling condition. However, participants exhibited more regular reading of the subtitles when the film soundtrack was in an unknown FL. To investigate the incidental acquisition of FL vocabulary, participants also completed an unexpected auditory vocabulary test. Because the results showed no vocabulary acquisition, the need for more sensitive measures of vocabulary acquisition are discussed. Finally, the reading of the subtitles is discussed in relation to the saliency of subtitles and automatic reading behavior. |
Laura Eklinder Björnström; Charlotte S. Hills; Hashim M. Hanif; Jason J. S. Barton Visual word expertise: A study of inversion and the word-length effect, with perceptual transforms Journal Article In: Perception, vol. 43, no. 5, pp. 438–450, 2014. @article{Bjoernstroem2014, The word-length effect may indicate whether reading is proceeding in an efficient whole-word fashion or by serial letter processing. If it is an index of an orientation-dependent expert reading mechanism, then it should show an inversion effect, with a large difference between upright and upside-down text that is specific for normally configured text. We measured response time of healthy subjects reading 3- to 9-letter words presented in normal configuration, in mirror reflection or spelt backward, in either upright or inverted orientation. The word-length effect showed an inversion effect specific for normal text, as it was not seen for either backward or mirrored text, a result that differed from that for simple mean response times. Also, the word-length effect was smaller for backward than for mirrored text, suggesting that reading of transformed text uses primarily local letters rather than global word forms. We conclude that the word-length effect is a suitable index of expert reading, and reveals that reading under perceptually difficult conditions relies on a sublexical letter-based strategy. |
Robert G. Alexander; Joseph Schmidt; Gregory J. Zelinsky Are summary statistics enough? Evidence for the importance of shape in guiding visual search Journal Article In: Visual Cognition, vol. 22, no. 3, pp. 595–609, 2014. @article{Alexander2014, Peripheral vision outside the focus of attention may rely on summary statistics. We used a gaze-contingent paradigm to directly test this assumption by asking whether search performance differed between targets and statistically-matched visualizations of the same targets. Four-object search displays included one statistically-matched object that was replaced by an unaltered version of the object during the first eye movement. Targets were designated by previews, which were never altered. Two types of statistically-matched objects were tested: One that maintained global shape and one that did not. Differences in guidance were found between targets and statistically-matched objects when shape was not preserved, suggesting that they were not informationally equivalent. Responses were also slower after target fixation when shape was not preserved, suggesting an extrafoveal processing of the target that again used shape information. We conclude that summary statistics must include some global shape information to approximate the peripheral information used during search. |
Eric S. Allard; Elizabeth A. Kensinger Age-related differences in neural recruitment during the use of cognitive reappraisal and selective attention as emotion regulation strategies Journal Article In: Frontiers in Psychology, vol. 5, pp. 296, 2014. @article{Allard2014, The present study examined age differences in the timing and neural recruitment within lateral and medial PFC while younger and older adults hedonically regulated their responses to unpleasant film clips. When analyses focused on activity during the emotional peak of the film clip (the most emotionally salient portion of the film), several age differences emerged. When comparing regulation to passive viewing (combined effects of selective attention and reappraisal) younger adults showed greater regulation related activity in lateral PFC (DLPFC, VLPFC, OFC) and medial PFC (ACC) while older adults showed greater activation within a region DLPFC. When assessing distinct effects of the regulation conditions, an ANOVA revealed a significant Age x Regulation Condition interaction within bilateral DLPFC and ACC; older adults but not young adults showed greater recruitment within these regions for reappraisal than selective attention. When examining activity at the onset of the film clip and at its emotional peak, the timing of reappraisal-related activity within VLPFC differed between age groups: younger adults showed greater activity at film onset while older adults showed heightened activity during the peak. Our results suggest that older adults rely more heavily on PFC recruitment when engaging cognitively demanding reappraisal strategies while PFC-mediated regulation might not be as task-specific for younger adults. Older adults' greater reliance on cognitive control processing during emotion regulation may also be reflected in the time needed to implement these strategies. |
Eric S. Allard; Elizabeth A. Kensinger Age-related differences in functional connectivity during cognitive emotion regulation Journal Article In: Journals of Gerontology - Series B Psychological Sciences and Social Sciences, vol. 69, no. 6, pp. 852–860, 2014. @article{Allard2014a, OBJECTIVES: Successful emotion regulation partly depends on our capacity to modulate emotional responses through the use of cognitive strategies. Age may affect the strategies employed most often; thus, we examined younger and older adults' neural network connectivity when employing two different strategies: cognitive reappraisal and selective attention.$backslash$n$backslash$nMETHOD: The current study used psychophysiological interaction analyses to examine functional connectivity with a region of anterior cingulate cortex (ACC) because it is a core part of an emotion regulation network showing relative structural preservation with age.$backslash$n$backslash$nRESULTS: Functional connectivity between ACC and prefrontal cortex (PFC) was greater for reappraisal relative to selective attention and passive viewing conditions for both age groups. For younger adults, ACC was more strongly connected with lateral dorsolateral PFC, ventrolateral PFC, dorsomedial PFC, and posterior cingulate regions during reappraisal. For older adults, stronger connectivity during reappraisal was observed primarily in ventromedial PFC and orbitofrontal cortex.$backslash$n$backslash$nDISCUSSION: Our results suggest that although young and older adults engage PFC networks during regulation, and particularly during reappraisal, the regions within these networks might differ. Additionally, these results clarify that, despite prior evidence for age-related declines in the structure and function of those regions, older adults are able to recruit ACC and PFC regions as part of coherent network during emotion regulation. |
Ted S. Altschuler; Sophie Molholm; John S. Butler; Manuel R. Mercier; Alice B. Brandwein; John J. Foxe In: NeuroImage, vol. 90, pp. 360–373, 2014. @article{Altschuler2014, The adult human visual system can efficiently fill-in missing object boundaries when low-level information from the retina is incomplete, but little is known about how these processes develop across childhood. A decade of visual-evoked potential (VEP) studies has produced a theoretical model identifying distinct phases of contour completion in adults. The first, termed a perceptual phase, occurs from approximately 100-200. ms and is associated with automatic boundary completion. The second is termed a conceptual phase occurring between 230 and 400. ms. The latter has been associated with the analysis of ambiguous objects which seem to require more effort to complete. The electrophysiological markers of these phases have both been localized to the lateral occipital complex, a cluster of ventral visual stream brain regions associated with object-processing. We presented Kanizsa-type illusory contour stimuli, often used for exploring contour completion processes, to neurotypical persons ages 6-31 (N. = 63), while parametrically varying the spatial extent of these induced contours, in order to better understand how filling-in processes develop across childhood and adolescence. Our results suggest that, while adults complete contour boundaries in a single discrete period during the automatic perceptual phase, children display an immature response pattern-engaging in more protracted processing across both timeframes and appearing to recruit more widely distributed regions which resemble those evoked during adult processing of higher-order ambiguous figures. However, children older than 5. years of age were remarkably like adults in that the effects of contour processing were invariant to manipulation of contour extent. |
Ilhame Ameqrane; Pierre Pouget; Nicolas Wattiez; Roger Carpenter; Marcus Missal Implicit and explicit timing in oculomotor control Journal Article In: PLoS ONE, vol. 9, no. 4, pp. e93958, 2014. @article{Ameqrane2014, The passage of time can be estimated either explicitly, e.g. before leaving home in the morning, or implicitly, e.g. when catching a flying ball. In the present study, the latency of saccadic eye movements was used to evaluate differences between implicit and explicit timing. Humans were required to make a saccade between a central and a peripheral position on a computer screen. The delay between the extinction of a central target and the appearance of an eccentric target was the independent variable that could take one out of four different values (400, 900, 1400 or 1900 ms). In target trials, the delay period lasted for one of the four durations randomly. At the end of the delay, a saccade was initiated by the appearance of an eccentric target. Cue&target trials were similar to target trials but the duration of the delay was visually cued. In probe trials, the duration of the upcoming delay was cued, but there was no eccentric target and subjects had to internally generate a saccade at the estimated end of the delay. In target and cue&target trials, the mean and variance of latency distributions decreased as delay duration increased. In cue&target trials latencies were shorter. In probe trials, the variance increased with increasing delay duration and scalar variability was observed. The major differences in saccadic latency distributions were observed between visually-guided (target and cue&target trials) and internally-generated saccades (probe trials). In target and cue&target trials the timing of the response was implicit. In probe trials, the timing of the response was internally-generated and explicitly based on the duration of the visual cue. Scalar timing was observed only during probe trials. This study supports the hypothesis that there is no ubiquitous timing system in the brain but independent timing processes active depending on task demands. |
Bernhard Angele; Abby E. Laishley; Keith Rayner; Simon P. Liversedge The effect of high- and low-frequency previews and sentential fit on word skipping during reading Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 40, no. 4, pp. 1181–1203, 2014. @article{Angele2014, In a previous gaze-contingent boundary experiment, Angele and Rayner (2013) found that readers are likely to skip a word that appears to be the definite article the even when syntactic constraints do not allow for articles to occur in that position. In the present study, we investigated whether the word frequency of the preview of a 3-letter target word influences a reader's decision to fixate or skip that word. We found that the word frequency rather than the felicitousness (syntactic fit) of the preview affected how often the upcoming word was skipped. These results indicate that visual information about the upcoming word trumps information from the sentence context when it comes to making a skipping decision. Skipping parafoveal instances of the therefore may simply be an extreme case of skipping high-frequency words. |
Mari Anzai; Soich Nagao Motor learning in common marmosets: Vestibulo-ocular reflex adaptation and its sensitivity to inhibitors of Purkinje cell long-term depression Journal Article In: Neuroscience Research, vol. 83, pp. 33–42, 2014. @article{Anzai2014, Adaptation of the horizontal vestibulo-ocular reflex (HVOR) provides an experimental model for cerebellum-dependent motor learning. We developed an eye movement measuring system and a paradigm for induction of HVOR adaptation for the common marmoset. The HVOR gain in dark measured by 10° (peak-to-peak amplitude) and 0.11-0.5. Hz turntable oscillation was around unity. The gain-up and gain-down HVOR adaptation was induced by 1. h of sustained out-of-phase and in-phase 10°-0.33. Hz combined turntable-screen oscillation in the light, respectively. To examine the role of long-term depression (LTD) of parallel fiber-Purkinje cell synapses, we intraperitonially applied T-588 or nimesulide, which block the induction of LTD in vitro or in vivo preparations, 1. h before the test of HVOR adaptation. T-588 (3 and 5. mg/kg body weight) did not affect nonadapted HVOR gains, and impaired both gain-up and gain-down HVOR adaptation. Nimesulide (3 and 6. mg/kg) did not affect nonadapted HVOR gains, and impaired gain-up HVOR adaptation dose-dependently; however, it very little affected gain-down HVOR adaptation. These findings are consistent with the results of our study of nimesulide on the adaptation of horizontal optokinetic response in mice (. Le et al., 2010), and support the view that LTD underlies HVOR adaptation. |
Rebecca L. Bassett-Gunter; Amy E. Latimer-Cheung; Kathleen A. Martin Ginis; Monica S. Castelhano I spy with my little eye: Cognitive processing of framed physical activity messages Journal Article In: Journal of Health Communication, vol. 19, no. 6, pp. 676–691, 2014. @article{BassettGunter2014, The primary purpose was to examine the relative cognitive processing of gain-framed versus loss-framed physical activity messages following exposure to health risk information. Guided by the Extended Parallel Process Model, the secondary purpose was to examine the relation between dwell time, message recall, and message-relevant thoughts, as well as perceived risk, personal relevance, and fear arousal. Baseline measures of perceived risk for inactivity-related disease and health problems were administered to 77 undergraduate students. Participants read population-specific health risk information while wearing a head-mounted eye tracker, which measured dwell time on message content. Perceived risk was then reassessed. Next, participants read PA messages while the eye tracker measured dwell time on message content. Immediately following message exposure, recall, thought-listing, fear arousal, and personal relevance were measured. Dwell time on gain-framed messages was significantly greater than loss-framed messages. However, message recall and thought-listing did not differ by message frame. Dwell time was not significantly related to recall or thought-listing. Consistent with the Extended Parallel Process Model, fear arousal was significantly related to recall, thought-listing, and personal relevance. In conclusion, gain-framed messages may evoke greater dwell time than loss-famed messages. However, dwell time alone may be insufficient for evoking further cognitive processing |
Oliver Baumann; Jason B. Mattingley Effects of attention and perceptual uncertainty on cerebellar activity during visual motion perception Journal Article In: Cerebellum, vol. 13, no. 1, pp. 46–54, 2014. @article{Baumann2014, Recent clinical and neuroimaging studies have revealed that the human cerebellum plays a role in visual motion perception, but the nature of its contribution to this function is not understood. Some reports suggest that the cerebellum might facilitate motion perception by aiding attentive tracking of visual objects. Others have identified a particular role for the cerebellum in discriminating motion signals in perceptually uncertain conditions. Here, we used functional magnetic resonance imaging to determine the degree to which cerebellar involvement in visual motion perception can be explained by a role in sustained attentive tracking of moving stimuli in contrast to a role in visual motion discrimination. While holding the visual displays constant, we manipulated attention by having participants attend covertly to a field of random-dot motion or a colored spot at fixation. Perceptual uncertainty was manipulated by varying the percentage of signal dots contained within the random-dot arrays. We found that attention to motion under high perceptual uncertainty was associated with strong activity in left cerebellar lobules VI and VII. By contrast, attending to motion under low perceptual uncertainty did not cause differential activation in the cerebellum. We found no evidence to support the suggestion that the cerebellum is involved in simple attentive tracking of salient moving objects. Instead, our results indicate that specific subregions of the cerebellum are involved in facilitating the detection and discrimination of task-relevant moving objects under conditions of high perceptual uncertainty. We conclude that the cerebellum aids motion perception under conditions of high perceptual demand. |
Carol L. Baym; Naiman A. Khan; Jim M. Monti; Lauren B. Raine; Eric S. Drollette; R. Davis Moore; Mark R. Scudder; Arthur F. Kramer; Charles H. Hillman; Neal J. Cohen Dietary lipids are differentially associated with hippocampal-dependent relational memory in prepubescent children Journal Article In: American Journal of Clinical Nutrition, vol. 99, no. 5, pp. 1026–1033, 2014. @article{Baym2014, BACKGROUND: Studies in rodents and older humans have shown that the hippocampus-a brain structure critical to relational/associative memory-has remarkable plasticity as a result of lifestyle factors (eg, exercise). However, the effect of dietary intake on hippocampal-dependent memory during childhood has remained unexamined.$backslash$n$backslash$nOBJECTIVE: We investigated the cross-sectional relation of dietary components characteristic of the Western diet, including saturated fatty acids (SFAs), omega-3 (n-3) fatty acids, and refined sugar, with hippocampal-dependent relational memory in prepubescent children.$backslash$n$backslash$nDESIGN: Participants aged 7-9 y (n = 52) reported their dietary intake by using the Youth-Adolescent Food-Frequency Questionnaire and completed memory tasks designed to assess relational (hippocampal-dependent) and item (hippocampal-independent) memory. Performance on the memory tasks was assessed with both direct (accuracy) and indirect (eye movement) measures.$backslash$n$backslash$nRESULTS: Partial correlations adjusted for body mass index showed a positive relation between relational memory accuracy and intake of omega-3 fatty acids and a negative relation of both relational and item memory accuracy with intake of SFAs. Potential confounding factors of age, sex, intelligence quotient, socioeconomic status, pubertal timing, and aerobic fitness (maximal oxygen volume) were not significantly related to any of the dietary intake measures. Eye movement measures of relational memory (preferential viewing to the target stimulus) showed a negative relation with intake of added sugar.$backslash$n$backslash$nCONCLUSIONS: SFA intake was negatively associated with both forms of memory, whereas omega-3 fatty acid intake was selectively positively associated with hippocampal-dependent relational memory. These findings are among the first to show a link between habitual dietary intake and cognitive health as pertaining to hippocampal function in childhood. |
Paul M. Bays Noise in neural populations accounts for errors in working memory Journal Article In: Journal of Neuroscience, vol. 34, no. 10, pp. 3632–3645, 2014. @article{Bays2014, Errors in short-term memory increase with the quantity of information stored, limiting the complexity of cognition and behavior. In visual memory, attempts to account for errors in terms of allocation of a limited pool of working memory resources have met with some success, but the biological basis for this cognitive architecture is unclear. An alternative perspective attributes recall errors to noise in tuned populations of neurons that encode stimulus features in spiking activity. I show that errors associated with decreasing signal strength in probabilistically spiking neurons reproduce the pattern of failures in human recall under increasing memory load. In particular, deviations from the normal distribution that are characteristic of working memory errors and have been attributed previously to guesses or variability in precision are shown to arise as a natural consequence of decoding populations of tuned neurons. Observers possess fine control over memory representations and prioritize accurate storage of behaviorally relevant information, at a cost to lower priority stimuli. I show that changing the input drive to neurons encoding a prioritized stimulus biases population activity in a manner that reproduces this empirical tradeoff in memory precision. In a task in which predictive cues indicate stimuli most probable for test, human observers use the cues in an optimal manner to maximize performance, within the constraints imposed by neural noise. |
Olivia Beaudry; Annie Roy-Charland; Melanie Perron; Isabelle Cormier; Roxane Tapp Featural processing in recognition of emotional facial expressions Journal Article In: Cognition and Emotion, vol. 28, no. 3, pp. 416–432, 2014. @article{Beaudry2014, The present study aimed to clarify the role played by the eye/brow and mouth areas in the recognition of the six basic emotions. In Experiment 1, accuracy was examined while participants viewed partial and full facial expressions; in Experiment 2, participants viewed full facial expressions while their eye movements were recorded. Recognition rates were consistent with previous research: happiness was highest and fear was lowest. The mouth and eye/brow areas were not equally important for the recognition of all emotions. More precisely, while the mouth was revealed to be important in the recognition of happiness and the eye/brow area of sadness, results are not as consistent for the other emotions. In Experiment 2, consistent with previous studies, the eyes/brows were fixated for longer periods than the mouth for all emotions. Again, variations occurred as a function of the emotions, the mouth having an important role in happiness and the eyes/brows in sadness. The general pattern of results for the other four emotions was inconsistent between the experiments as well as across different measures. The complexity of the results suggests that the recognition process of emotional facial expressions cannot be reduced to a simple feature processing or holistic processing for all emotions. |
Genna M. Bebko; Steven L. Franconeri; Kevin N. Ochsner; Joan Y. Chiao Attentional deployment is not necessary for successful emotion regulation via cognitive reappraisal or expressive suppression Journal Article In: Emotion, vol. 14, no. 3, pp. 504–512, 2014. @article{Bebko2014, According to appraisal theories of emotion, cognitive reappraisal is a successful emotion regulation strategy because it involves cognitively changing our thoughts, which, in turn, change our emotions. However, recent evidence has challenged the importance of cognitive change and, instead, has suggested that attentional deployment may at least partly explain the emotion regulation success of cognitive reappraisal. The purpose of the current study was to examine the causal relationship between attentional deployment and emotion regulation success. We examined 2 commonly used emotion regulation strategies-cognitive reappraisal and expressive suppression-because both depend on attention but have divergent behavioral, experiential, and physiological outcomes. Participants were either instructed to regulate emotions during free-viewing (unrestricted image viewing) or gaze-controlled (restricted image viewing) conditions and to self-report negative emotional experience. For both emotion regulation strategies, emotion regulation success was not altered by changes in participant control over the (a) direction of attention (free-viewing vs. gaze-controlled) during image viewing and (b) valence (negative vs. neutral) of visual stimuli viewed when gaze was controlled. Taken together, these findings provide convergent evidence that attentional deployment does not alter subjective negative emotional experience during either cognitive reappraisal or expressive suppression, suggesting that strategy-specific processes, such as cognitive appraisal and response modulation, respectively, may have a greater impact on emotional regulation success than processes common to both strategies, such as attention. |
Elizabeth H. Beck; Anthony A. Amato; Steven A. Greenberg; Elizabeth H. Beck Improvement of internuclear ophthalmoparesis in multiple sclerosis with dalfampridine Journal Article In: Neurology, vol. 83, pp. 192–194, 2014. @article{Beck2014, Internuclear ophthalmoparesis (INO) in multiple sclerosis (MS) is due to demyelination of the medial longitudinal fasciculus (MLF) and provides an acces- sible model for studying consequences of raised body temperature and fatigue on central demyelination.1,2 Prompted by one of our patient's report of vision improvement after initiating dalfampridine, a potas- sium channel blocker prescribed for gait impairment,3 we measured this drug's effects on 3 patients with MS with bilateral INO. All showed changes in horizontal saccadic conjugacy consistent with improved trans- mission of the neural pulse responsible for adducting movements. |
Melissa R. Beck; S. Lee Hong; Amanda E. Lamsweerde; Justin M. Ericson In: PLoS ONE, vol. 9, no. 4, pp. e94539, 2014. @article{Beck2014a, Responses are quicker to predictable stimuli than if the time and place of appearance is uncertain. Studies that manipulate target predictability often involve overt cues to speed up response times. However, less is known about whether individuals will exhibit faster response times when target predictability is embedded within the inter-trial relationships. The current research examined the combined effects of spatial and temporal target predictability on reaction time (RT) and allocation of overt attention in a sustained attention task. Participants responded as quickly as possible to stimuli while their RT and eye movements were measured. Target temporal and spatial predictability were manipulated by altering the number of: 1) different time intervals between a response and the next target; and 2) possible spatial locations of the target. The effects of target predictability on target detection (Experiment 1) and target discrimination (Experiment 2) were tested. For both experiments, shorter RTs as target predictability increased across both space and time were found. In addition, the influences of spatial and temporal target predictability on RT and the overt allocation of attention were task dependent; suggesting that effective orienting of attention relies on both spatial and temporal predictability. These results indicate that stimulus predictability can be increased without overt cues and detected purely through inter-trial relationships over the course of repeated stimulus presentations. |
Stefanie I. Becker; Anthony M. Harris; Dustin Venini; James D. Retell Visual search for color and shape: When is the gaze guided by feature relationships, when by feature values? Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 40, no. 1, pp. 264–291, 2014. @article{Becker2014, One of the most widespread views in vision research is that top-down control over visual selection is achieved by tuning attention to a particular feature value (e.g., red/yellow). Contrary to this view, previous spatial cueing studies showed that attention can be tuned to relative features of a search target (e.g., redder): An irrelevant distractor (cue) captured attention when it had the same relative color as the target (e.g., redder), and failed to capture when it had a different relative color, regardless of whether the distractor was similar or dissimilar to the target. The present study tested whether the same effects would be observed for eye movements when observers have to search for a color or shape target and when selection errors were very noticeable (resulting in an erroneous eye movement to the distractor). The results corroborated the previous findings, showing that capture by an irrelevant distractor does not depend on the distractor's similarity to the target but on whether it matches or mismatches the relative attributes of the search target. Extending on previous work, we also found that participants can be pretrained to select a color target in virtue of its exact feature value. Contrary to the prevalent feature-based view, the results suggest that visual selection is preferentially biased toward the relative attributes of a search target. Simultaneously, however, visual selection can be biased to specific color values when the task requires it, which rules out a purely relational account of attention and eye movements. (PsycINFO Database Record (c) 2014 APA, all rights reserved). |
Stefanie I. Becker; Christian Valuch; Ulrich Ansorge Color priming in pop-out search depends on the relative color of the target Journal Article In: Frontiers in Psychology, vol. 5, pp. 289, 2014. @article{Becker2014a, In visual search for pop-out targets, search times are shorter when the target and non-target colors from the previous trial are repeated than when they change. This priming effect was originally attributed to a feature weighting mechanism that biases attention toward the target features, and away from the non-target features. However, more recent studies have shown that visual selection is strongly context-dependent: according to a relational account of feature priming, the target color is always encoded relative to the non-target color (e.g., as redder or greener). The present study provides a critical test of this hypothesis, by varying the colors of the search items such that either the relative color or the absolute color of the target always remained constant (or both). The results clearly show that color priming depends on the relative color of a target with respect to the non-targets but not on its absolute color value. Moreover, the observed priming effects did not change over the course of the experiment, suggesting that the visual system encodes colors in a relative manner from the start of the experiment. Taken together, these results strongly support a relational account of feature priming in visual search, and are inconsistent with the dominant feature-based views. |
Y. Behnke Visual qualities of future geography books Journal Article In: European Journal of Geography, vol. 5, no. 4, pp. 56–66, 2014. @article{Behnke2014, The capacity for spatial orientation and associated faculties are closely related to visual competencies. Consequently, the practice and acquisition of visual competencies are vital prerequisites to successful learning and teaching of geography. Today, geography can be understood as a visual discipline and as such may develop strong links to visual communication. In geography, textbooks may establish this link in an everyday context. This Ph.D. project aims to build the bridge between subject content and design. The result will be a visually convincing geography textbook prototype. Fifty-six geography textbooks from different European countries were analysed, focussing on the design concept. Furthermore, double-page spreads of current German geography textbooks were evaluated by observing students' textbook usage via eye tracking. Eye tracking monitors students' reactions to varying contents and designs. Findings from both analyses form the basis for the textbook concept, which is to be developed. |
Ashley Benatar; Charles Clifton Newness, givenness and discourse updating: Evidence from eye movements Journal Article In: Journal of Memory and Language, vol. 71, no. 1, pp. 1–16, 2014. @article{Benatar2014, Three experiments examined the effect of contextual givenness on eye movements in reading, following Schwarzschild's (1999) analysis of givenness and focus-marking in which relations among entities as well as the entities themselves can be given. In each study, a context question was followed by an answer in which a critical word was either given, new, or contrastively (correctively) focused. Target words were read faster when the critical word provided given information than when it provided new information, and faster when it provided new information than when it corrected prior information. Repetition of target words was controlled in two ways: by mentioning a non-given target word in the context in a relation other than that in which it occurred as a target, and by using a synonym or subordinate of a given target to refer to it in the context question. Verbatim repetition was not responsible for the observed effects of givenness and contrastiveness. Besides clarifying previous inconsistent results of the effects of focus and givenness on reading speed, these results indicate that reading speed can be influenced essentially immediately by a reader's discourse representation, and that the extent of the influence is graded, with corrections to a representation having a larger effect than simple additions. |
Manabu Arai; Reiko Mazuka The development of Japanese passive syntax as indexed by structural priming in comprehension Journal Article In: Quarterly Journal of Experimental Psychology, vol. 67, no. 1, pp. 60–78, 2014. @article{Arai2014, A number of previous studies reported a phenomenon of syntactic priming with young children as evidence for cognitive representations required for processing syntactic structures. However, it remains unclear how syntactic priming reflects children's grammatical competence. The current study investigated structural priming of the Japanese passive structure with 5- and 6-year-old children in a visual-world setting. Our results showed a priming effect as anticipatory eye movements to an upcoming referent in these children but the effect was significantly stronger in magnitude in 6-year-olds than in 5-year-olds. Consistently, the responses to comprehension questions revealed that 6-year-olds produced a greater number of correct answers and more answers using the passive structure than 5-year-olds. We also tested adult participants who showed even stronger priming than the children. The results together revealed that language users with the greater linguistic competence with the passives exhibited stronger priming, demonstrating a tight relationship between the effect of priming and the development of grammatical competence. Furthermore, we found that the magnitude of the priming effect decreased over time. We interpret these results in the light of an error-based learning account. Our results also provided evidence for prehead as well as head-independent priming. |
Anne Atas; Nathan Faivre; Bert Timmermans; Axel Cleeremans; Sid Kouider Nonconscious learning from crowded sequences Journal Article In: Psychological Science, vol. 25, no. 1, pp. 113–119, 2014. @article{Atas2014, Can people learn complex information without conscious awareness? Implicit learning-learning without awareness of what has been learned-has been the focus of intense investigation over the last 50 years. However, it remains controversial whether complex knowledge can be learned implicitly. In the research reported here, we addressed this challenge by asking participants to differentiate between sequences of symbols they could not perceive consciously. Using an operant-conditioning task, we showed that participants learned to associate distinct sequences of crowded (nondiscriminable) symbols with their respective monetary outcomes (reward or punishment). Overall, our study demonstrates that sensitivity to sequential regularities can arise through the nonconscious temporal integration of perceptual information. |
Jeroen Atsma; Femke Maij; Brian D. Corneil; W. Pieter Medendorp No perisaccadic mislocalization with abruptly cancelled saccades Journal Article In: Journal of Neuroscience, vol. 34, no. 16, pp. 5497–5504, 2014. @article{Atsma2014, Every saccadic eye movement that we make changes the image of the world on our retina. Yet, despite these retinal shifts, we still perceive our visual world to be stable. Efference copy from the oculomotor system to the visual system has been suggested to contribute to this stable percept, enabling the brain to anticipate the retinal image shifts by remapping the neural image. A psychophysical phenomenon that has been linked to this predictive remapping is the mislocalization of a stimulus flashed around the time of a saccade. If this mislocalization is initiated by saccade preparation, one should also observe localization errors when a saccade is planned, but abruptly aborted just before its execution. We tested this hypothesis in human subjects using a novel paradigm that combines a flash localization task with a countermanding component that occasionally requires saccade cancellation. Surprisingly, we found no trace of mislocalization, even for saccades cancelled close to the point of no return. This strongly suggests that the actual execution of the saccade is a prerequisite for the typical localization errors, which rejects various models and constrains neural substrates. We conclude that perisaccadic mislocalization is not a direct consequence of saccade preparation, but arises after saccade execution when the flash location is constructed from memory. |
Janice Attard; Markus Bindemann Establishing the duration of crimes: An individual differences and eye-tracking investigation into time estimation Journal Article In: Applied Cognitive Psychology, vol. 28, no. 2, pp. 215–225, 2014. @article{Attard2014, The time available for viewing a perpetrator at a crime scene predicts successful person recognition in subsequent identity line-ups. This time is usually unknown and must be derived from eyewitnesses' duration estimates. This study therefore compared the estimates that different individuals provide for crimes. We then attempted to determine the accuracy of these durations by measuring observers' general time estimation ability with a set of estimator videos. Observers differed greatly in their ability to estimate time, but individual duration estimates correlated strongly for crime and estimator materials. This indicates that it might be possible to infer unknown durations of events, such as criminal incidents, from a person's ability to estimate known durations. We also measured observers' eye movements to a perpetrator during crimes. Only fixations on a perpetrator's face related to eyewitness accuracy, but these fixations did not correlate with exposure estimates for this person. The implications of these findings are discussed. |
Sheena K. Au-Yeung; Johanna K. Kaakinen; Valerie Benson Cognitive perspective-taking during scene perception in autism spectrum disorder: Evidence from eye movements Journal Article In: Autism Research, vol. 7, no. 1, pp. 84–93, 2014. @article{AuYeung2014, The present study examined how eye movements during scene viewing are modulated by adopting psychological perspectives in both adults with autism spectrum disorders (ASD) and typically developing adults. In the current study, participants viewed house scenes with either non-perspective-taking (look for valuable items/features of the house that need fixing) or perspective-taking instructions (imagine that you are a burglar/repairman) while their eye movements were recorded. The eye movement measures revealed that for the “look for the valuable items” and burglar perspective task, the ASD group showed typical relevance effects (the preference to look at schema-relevant compared with schema-irrelevant targets) in their eye movements. However, we found subtle processing differences between the groups that were related to initial orienting to and processing of schema-relevant items for the “look for the features that need fixing” and the repairman perspective-taking task. There was an absence of a relevance effect for the ASD group for the repairman perspective and its non-perspective-taking equivalent instruction showing that the identification of items relevant to those schemas was more difficult for the ASD group. The present findings suggest that resolving ambiguity may be a defining feature of complex information processing deficits in ASD. |
Reza Azadi; Mark R. Harwood Visual cues that are effective for contextual saccade adaptation Journal Article In: Journal of Neurophysiology, vol. 111, no. 11, pp. 2307–2319, 2014. @article{Azadi2014, The accuracy of saccades, as maintained by saccade adaptation, has been shown to be context dependent: able to have different amplitude movements to the same retinal displacement dependent on motor contexts such as orbital starting location. There is conflicting evidence as to whether purely visual cues also effect contextual saccade adaptation and, if so, what function this might serve. We tested what visual cues might evoke contextual adaptation. Over 5 experiments, 78 naive subjects made saccades to circularly moving targets, which stepped outward or inward during the saccade depending on target movement direction, speed, or color and shape. To test if the movement or context postsaccade were critical, we stopped the postsaccade target motion ( experiment 4 ) or neutralized the contexts by equating postsaccade target speed to an intermediate value ( experiment 5 ). We found contextual adaptation in all conditions except those defined by color and shape. We conclude that some, but not all, visual cues before the saccade are sufficient for contextual adaptation. We conjecture that this visual contextuality functions to allow for different motor states for different coordinated movement patterns, such as coordinated saccade and pursuit motor planning. |
Raiju J. Babu; Susan J. Leat; Elizabeth L. Irving Effect of age and pop out distracter on attended field of view Journal Article In: Journal of Optometry, vol. 7, pp. 229–237, 2014. @article{Babu2014, Purpose: To investigate the functional field of view (FFOV) of younger and older individuals using the attended field of view (AFOV), a method which allows for eye and head movement. The impact of a pop out distracter and a dual task on the FFOV measure was also investigated. Methods: Nine young adult (25 ± 6 years) and 9 older participants (72 ± 4 years) took part in the experiment. The AFOV test involved the binocular detection and localization of a white target (Landolt-C) in a field of 24 white rings (distracters). The further AFOV tests were modified to include the presence of a pop out distracter, a dual task condition, and a combination of the two. Results: Older observers had lower viewing efficiency (log [1/presentation time]) in all con- ditions (pooled mean across conditions: older: 0.05 ± 0.02; younger: 0.48 ± 0.04) than the younger group. The addition of dual or a pop out distracter did not affect the older group (mean difference ∼104 ± 150 ms and ∼124 ± 122 ms respectively) but the additional pop out distracter reduced the efficiency of the younger group for targets near fixation (mean difference ∼68 ± 35 ms). Conclusion: Better viewing efficiency was observed in younger individuals compared to older individuals. Difficulty in disregarding irrelevant stimuli and thereby resorting to inefficient search strategy is proposed as the reason for the differences. The finding that both older and younger individuals are not affected significantly by the presence of the irrelevant pop out distracter has implications in situations such as driving or hazard avoidance. In such scenarios, search performance is likely not impaired beyond what is found with distracters (visual clutter) in the environment. |
Dong-Hyun Baek; Jeyeon Lee; Hang Byeon; Hoseok Choi; In Young Kim; Kyoung-Min Lee; James Jungho Pak; Dong Pyo Jang; Sang-Hoon Lee A thin film polyimide mesh microelectrode for chronic epidural electrocorticography recording with enhanced contactability Journal Article In: Journal of Neural Engineering, vol. 11, no. 4, pp. 1–10, 2014. @article{Baek2014, Objective. Epidural electrocorticography (ECoG) activity may be more reliable and stable than single-unit-activity or local field potential. Invasive brain computer interface (BCI) devices are limited by mechanical mismatching and cellular reactive responses due to differences in the elastic modulus and the motion of stiff electrodes. We propose a mesh-shaped electrode to enhance the contactability between surface of dura and electrode. Approach. We designed a polyimide (PI) electrode with a mesh pattern for more conformal contact with a curved surface. We compared the contact capability of mesh PI electrodes with conventionally used sheet PI electrode. The electrical properties of the mesh PI electrode were evaluated for four weeks. We recorded the epidural ECoG (eECoG) activity on the surface of rhesus monkey brains while they performed a saccadic task for four months. Main results. The mesh PI electrode showed good contact with the agarose brain surface, as evaluated by visual inspection and signal measurement. It was about 87% accurate in predicting the direction of saccade eye movement. Significance. Our results indicate that the mesh PI electrode was flexible and good contact on the curved surface and can record eECoG activity maintaining close contact to dura, which was proved by in vivo and in vitro test. |
Daniel Baldauf; Robert Desimone Neural mechanisms of object-based attention Journal Article In: Science, vol. 344, no. 6182, pp. 424–427, 2014. @article{Baldauf2014, How we attend to objects and their features that cannot be separated by location is not understood. We presented two temporally and spatially overlapping streams of objects, faces versus houses, and used magnetoencephalography and functional magnetic resonance imaging to separate neuronal responses to attended and unattended objects. Attention to faces versus houses enhanced the sensory responses in the fusiform face area (FFA) and parahippocampal place area (PPA), respectively. The increases in sensory responses were accompanied by induced gamma synchrony between the inferior frontal junction, IFJ, and either FFA or PPA, depending on which object was attended. The IFJ appeared to be the driver of the synchrony, as gamma phases were advanced by 20 ms in IFJ compared to FFA or PPA. Thus, the IFJ may direct the flow of visual processing during object-based attention, at least in part through coupled oscillations with specialized areas such as FFA and PPA. W |
D. A. Barany; V. Della-Maggiore; Shivakumar Viswanathan; M. Cieslak; Scott T. Grafton Feature Iinteractions enable decoding of sensorimotor transformations for goal-directed movement Journal Article In: Journal of Neuroscience, vol. 34, no. 20, pp. 6860–6873, 2014. @article{Barany2014, Neurophysiology and neuroimaging evidence shows that the brain represents multiple environmental and body-related features to compute transformations from sensory input to motor output. However, it is unclear how these features interact during goal-directed movement. To investigate this issue, we examined the representations of sensory and motor features of human hand movements within the left-hemisphere motor network. In a rapid event-related fMRI design, we measured cortical activity as participants performed right-handed movements at the wrist, with either of two postures and two amplitudes, to move a cursor to targets at different locations. Using a multivoxel analysis technique with rigorous generalization tests, we reliably distinguished representations of task-related features (primarily target location, movement direction, and posture) in multiple regions. In particular, we identified an interaction between target location and movement direction in the superior parietal lobule, which may underlie a transformation from the location of the target in space to a movement vector. In addition, we found an influence of posture on primary motor, premotor, and parietal regions. Together, these results reveal the complex interactions between different sensory and motor features that drive the computation of sensorimotor transformations. |
Ellen Gurman Bard; Robin L. Hill; Mary Ellen Foster; Manabu Arai Tuning accessibility of referring expressions in situated dialogue Journal Article In: Language, Cognition and Neuroscience, vol. 29, no. 8, pp. 928–949, 2014. @article{Bard2014, Accessibility theory associates more complex referring expressions with less accessible referents. Felicitous referring expressions should reflect accessibility from the addressee's perspective, which may be difficult for speakers to assess incrementally. If mechanisms shared by perception and production help interlocutors align internal representations, then dyads with different roles and different things to say should profit less from alignment. We examined introductory mentions of on-screen shapes within a joint task for effects of access to the addressee's attention, of players' actions and of speakers' roles. Only speakers' actions affected the form of referring expression and only different role dyads made egocentric use of actions hidden from listeners. Analysis of players' gaze around referring expressions confirmed this pattern; only same role dyads coordinated attention as the accessibility theory predicts. The results are discussed within a model distributing collaborative effort under the cons... |
Anthony S. Barnhart; Stephen D. Goldinger Blinded by magic: Eye-movements reveal the misdirection of attention Journal Article In: Frontiers in Psychology, vol. 5, pp. 1461, 2014. @article{Barnhart2014, Recent studies (e.g., Kuhn and Tatler, 2005) have suggested that magic tricks can provide a powerful and compelling domain for the study of attention and perception. In particular, many stage illusions involve attentional misdirection, guiding the observer's gaze to a salient object or event, while another critical action, such as sleight of hand, is taking place. Even if the critical action takes place in full view, people typically fail to see it due to inattentional blindness (IB). In an eye-tracking experiment, participants watched videos of a new magic trick, wherein a coin placed beneath a napkin disappears, reappearing under a different napkin. Appropriately deployed attention would allow participants to detect the "secret" event that underlies the illusion (a moving coin), as it happens in full view and is visible for approximately 550 ms. Nevertheless, we observed high rates of IB. Unlike prior research, eye-movements during the critical event showed different patterns for participants, depending upon whether they saw the moving coin. The results also showed that when participants watched several "practice" videos without any moving coin, they became far more likely to detect the coin in the critical trial. Taken together, the findings are consistent with perceptual load theory (Lavie and Tsal, 1994). |
Dale J. Barr; Laura Jackson; Isobel Phillips Using a voice to put a name to a face: The psycholinguistics of proper name comprehension Journal Article In: Journal of Experimental Psychology: General, vol. 143, no. 1, pp. 404–413, 2014. @article{Barr2014, We propose that hearing a proper name (e.g., Kevin) in a particular voice serves as a compound memory cue that directly activates representations of a mutually known target person, often permitting reference resolution without any complex computation of shared knowledge. In a referential communication study, pairs of friends played a communication game, in which we monitored the eyes of one friend (the addressee) while he or she sought to identify the target person, in a set of four photos, on the basis of a name spoken aloud. When the name was spoken by a friend, addressees rapidly identified the target person, and this facilitation was independent of whether the friend was articulating a message he or she had designed versus one from a third party with whom the target person was not shared. Our findings suggest that the comprehension system takes advantage of regularities in the environment to minimize effortful computation about who knows what. |
Pablo A. Barrionuevo; Nathaniel Nicandro; J. Jason McAnany; Andrew J. Zele; Paul Gamlin; Dingcai Cao Assessing rod, cone, and melanopsin contributions to human pupil flicker responses Journal Article In: Investigative Ophthalmology & Visual Science, vol. 55, no. 2, pp. 719–727, 2014. @article{Barrionuevo2014, PURPOSE: We determined the relative contributions of rods, cones, and melanopsin to pupil responses in humans using temporal sinusoidal stimulation for light levels spanning the low mesopic to photopic range. METHODS: A four-primary Ganzfeld photostimulator controlled flicker stimulations at seven light levels (-2.7 to 2 log cd/m(2)) and five frequencies (0.5-8 Hz). Pupil diameter was measured using a high-resolution eye tracker. Three kinds of sinusoidal photoreceptor modulations were generated using silent substitution: rod modulation, cone modulation, and combined rod and cone modulation in phase (experiment 1) or cone phase shifted (experiment 2) from a fixed rod phase. The melanopsin excitation was computed for each condition. A vector sum model was used to estimate the relative contribution of rods, cones, and melanopsin to the pupil response. RESULTS: From experiment 1, the pupil frequency response peaked at 1 Hz at two mesopic light levels for the three modulation conditions. Analyzing the rod-cone phase difference for the combined modulations (experiment 2) identified a V-shaped response amplitude with a minimum between 135° and 180°. The pupil response phases increased as cone modulation phase increased. The pupil amplitude increased with increasing light level for cone, and combined (in-phase rod and cone) modulation, but not for the rod modulation. CONCLUSIONS: These results demonstrate that cone- and rod-pathway contributions are more predominant than melanopsin contribution to the phasic pupil response. The combined rod, cone, and melanopsin inputs to the phasic state of the pupil light reflex follow linear summation. |
Arielle Borovsky; Sarah C. Creel Children and adults integrate talker and verb information in online processing Journal Article In: Developmental Psychology, vol. 50, no. 5, pp. 1600–1613, 2014. @article{Borovsky2014, Children seem able to efficiently interpret a variety of linguistic cues during speech comprehension, yet have difficulty interpreting sources of nonlinguistic and paralinguistic information that accompany speech. The current study asked whether (paralinguistic) voice-activated role knowledge is rapidly interpreted in coordination with a linguistic cue (a sentential action) during speech comprehension in an eye-tracked sentence comprehension task with children (ages 3-10 years) and college-aged adults. Participants were initially familiarized with 2 talkers who identified their respective roles (e.g., PRINCESS and PIRATE) before hearing a previously introduced talker name an action and object ("I want to hold the sword," in the pirate's voice). As the sentence was spoken, eye movements were recorded to 4 objects that varied in relationship to the sentential talker and action (target: SWORD, talker-related: SHIP, action-related: WAND, and unrelated: CARRIAGE). The task was to select the named image. Even young child listeners rapidly combined inferences about talker identity with the action, allowing them to fixate on the target before it was mentioned, although there were developmental and vocabulary differences on this task. Results suggest that children, like adults, store real-world knowledge of a talker's role and actively use this information to interpret speech. |
Arielle Borovsky; Kim Sweeney; Jeffrey L. Elman; Anne Fernald Real-time interpretation of novel events across childhood Journal Article In: Journal of Memory and Language, vol. 73, no. 1, pp. 1–14, 2014. @article{Borovsky2014a, Despite extensive evidence that adults and children rapidly integrate world knowledge to generate expectancies for upcoming language, little work has explored how this knowledge is initially acquired and used. We explore this question in 3- to 10-year-old children and adults by measuring the degree to which sentences depicting recently learned connections between agents, actions and objects lead to anticipatory eye-movements to the objects. Combinatory information in sentences about agent and action elicited anticipatory eye-movements to the Target object in adults and older children. Our findings suggest that adults and school-aged children can quickly activate information about recently exposed novel event relationships in real-time language processing. However, there were important developmental differences in the use of this knowledge. Adults and school-aged children used the sentential agent and action to predict the sentence final theme, while preschool children's fixations reflected a simple association to the currently spoken item. We consider several reasons for this developmental difference and possible extensions of this paradigm. |
Hans Rutger Bosker; Hugo Quené; Ted J. M. Sanders; Nivja H. Jong Native 'um's elicit prediction of low-frequency referents, but non-native 'um's do not Journal Article In: Journal of Memory and Language, vol. 75, pp. 104–116, 2014. @article{Bosker2014, Speech comprehension involves extensive use of prediction. Linguistic prediction may be guided by the semantics or syntax, but also by the performance characteristics of the speech signal, such as disfluency. Previous studies have shown that listeners, when presented with the filler uh, exhibit a disfluency bias for discourse-new or unknown referents, drawing inferences about the source of the disfluency. The goal of the present study is to study the contrast between native and non-native disfluencies in speech comprehension. Experiment 1 presented listeners with pictures of high-frequency (e.g., a hand) and low-frequency objects (e.g., a sewing machine) and with fluent and disfluent instructions. Listeners were found to anticipate reference to low-frequency objects when encountering disfluency, thus attributing disfluency to speaker trouble in lexical retrieval. Experiment 2 showed that, when participants listened to disfluent non-native speech, no anticipation of low-frequency referents was observed. We conclude that listeners can adapt their predictive strategies to the (non-native) speaker at hand, extending our understanding of the role of speaker identity in speech comprehension. |
Marie Line Bosse; Sonia Kandel; Chloé Prado; Sylviane Valdois Does visual attention span relate to eye movements during reading and copying? Journal Article In: International Journal of Behavioral Development, vol. 38, no. 1, pp. 81–85, 2014. @article{Bosse2014, This research investigated whether text reading and copying involve visual attention-processing skills. Children in grades 3 and 5 read and copied the same text. We measured eye movements while reading and the number of gaze lifts (GL) during copying. The children were also administered letter report tasks that constitute an estimation of the number of letters that are processed simultaneously. The tasks were designed to assess visual attention span abilities (VA). The results for both grades revealed that the children who reported more letters, i.e., processed more consonants in parallel, produced fewer rightward fixations during text reading suggesting they could process more letters at each fixation. They also copied more letters per gaze lift from the same text. Furthermore, a regression analysis showed that VA span predicted variations in copying independently of the influence of reading skills. The findings support a role of VA span abilities in the early extraction of orthographic information, for both reading and copying tasks. |
Hanneke Bouwsema; Corry K. Sluis; Raoul M. Bongers Changes in performance over time while learning to use a myoelectric prosthesis Journal Article In: Journal of NeuroEngineering and Rehabilitation, vol. 11, no. 1, pp. 1–15, 2014. @article{Bouwsema2014, BACKGROUND: Training increases the functional use of an upper limb prosthesis, but little is known about how people learn to use their prosthesis. The aim of this study was to describe the changes in performance with an upper limb myoelectric prosthesis during practice. The results provide a basis to develop an evidence-based training program. METHODS: Thirty-one able-bodied participants took part in an experiment as well as thirty-one age- and gender-matched controls. Participants in the experimental condition, randomly assigned to one of four groups, practiced with a myoelectric simulator for five sessions in a two-weeks period. Group 1 practiced direct grasping, Group 2 practiced indirect grasping, Group 3 practiced fixating, and Group 4 practiced a combination of all three tasks. The Southampton Hand Assessment Procedure (SHAP) was assessed in a pretest, posttest, and two retention tests. Participants in the control condition performed SHAP two times, two weeks apart with no practice in between. Compressible objects were used in the grasping tasks. Changes in end-point kinematics, joint angles, and grip force control, the latter measured by magnitude of object compression, were examined. RESULTS: The experimental groups improved more on SHAP than the control group. Interestingly, the fixation group improved comparable to the other training groups on the SHAP. Improvement in global position of the prosthesis leveled off after three practice sessions, whereas learning to control grip force required more time. The indirect grasping group had the smallest object compression in the beginning and this did not change over time, whereas the direct grasping and the combination group had a decrease in compression over time. Moreover, the indirect grasping group had the smallest grasping time that did not vary over object rigidity, while for the other two groups the grasping time decreased with an increase in object rigidity. CONCLUSIONS: A training program should spend more time on learning fine control aspects of the prosthetic hand during rehabilitation. Moreover, training should start with the indirect grasping task that has the best performance, which is probably due to the higher amount of useful information available from the sound hand. |
Oliver Boxell Lexical fillers permit real-time gap-search inside island domains Journal Article In: Journal of Cognitive Science, vol. 14, no. 1, pp. 97–136, 2014. @article{Boxell2014, It has often been reported that lexical fillers (e.g. which house) improve the overall acceptability of many island constraint violations relative to bare fillers (e.g. what). The current study attempts to test for the first time whether lexical fillers reduce real-time sensitivity to wh-islands as well. Results from an eyetracking-while-reading study are reported that demonstrate native English speakers' sensitivity to a plausibility manipulation between a fronted filler phrase and a downstream subcategorizing verb inside a wh-island domain. The effect is found as the verb was encountered in real-time, and only when the filler element contains lexical information, not when it is bare. This is taken to show that online sensitivity to the wh-island constraint is reduced when the filler preceding it is lexical. The strengths and weaknesses and overall compatibility of a range of grammatical and processing theories are considered in relation to this finding. |
C. Bradley; Jared Abrams; Wilson S. Geisler Retina-V1 model of detectability across the visual field Journal Article In: Journal of Vision, vol. 14, no. 12, pp. 1–22, 2014. @article{Bradley2014, A practical model is proposed for predicting the detectability of targets at arbitrary locations in the visual field, in arbitrary gray scale backgrounds, and under photopic viewing conditions. The major factors incorporated into the model include (a) the optical point spread function of the eye, (b) local luminance gain control (Weber's law), (c) the sampling array of retinal ganglion cells, (d) orientation and spatial frequency-dependent contrast masking, (e) broadband contrast masking, and (f) efficient response pooling. The model is tested against previously reported threshold measurements on uniform backgrounds (the ModelFest data set and data from Foley, Varadharajan, Koh, & Farias, 2007) and against new measurements reported here for several ModelFest targets presented on uniform, 1/f noise, and natural backgrounds at retinal eccentricities ranging from 0 degrees to 10 degrees. Although the model has few free parameters, it is able to account quite well for all the threshold measurements. |
John Brand; Aaron P. Johnson Attention to local and global levels of hierarchical Navon figures affects rapid scene categorization Journal Article In: Frontiers in Psychology, vol. 5, pp. 1274, 2014. @article{Brand2014, In four experiments, we investigated how attention to local and global levels of hierarchical Navon figures affected the selection of diagnostic spatial scale information used in scene categorization. We explored this issue by asking observers to classify hybrid images (i.e., images that contain low spatial frequency (LSF) content of one image, and high spatial frequency (HSF) content from a second image) immediately following global and local Navon tasks. Hybrid images can be classified according to either their LSF, or HSF content; thus, making them ideal for investigating diagnostic spatial scale preference. Although observers were sensitive to both spatial scales (Experiment 1), they overwhelmingly preferred to classify hybrids based on LSF content (Experiment 2). In Experiment 3, we demonstrated that LSF based hybrid categorization was faster following global Navon tasks, suggesting that LSF processing associated with global Navon tasks primed the selection of LSFs in hybrid images. In Experiment 4, replicating Experiment 3 but suppressing the LSF information in Navon letters by contrast balancing the stimuli examined this hypothesis. Similar to Experiment 3, observers preferred to classify hybrids based on LSF content; however and in contrast, LSF based hybrid categorization was slower following global than local Navon tasks |
Eduard Brandstätter; Christof Körner Attention in risky choice Journal Article In: Acta Psychologica, vol. 152, pp. 166–176, 2014. @article{Brandstaetter2014, Previous research on the processes involved in risky decisions has rarely linked process data to choice directly. We used a simple measure based on the relative amount of attentional deployment to different components (gains/losses and their probabilities) of a risky gamble during the choice process, and we related this measure to the actual choice. In an experiment we recorded the decisions, decision times, and eye movements of 80 participants who made decisions on 11 choice problems. We used the number of eye fixations and fixation transitions to trace the deployment of attention during the choice process and obtained the following main results. First, different components of a gamble attracted different amounts of attention depending on participants' actual choice. This was reflected in both the number of fixations and the fixation transitions. Second, the last-fixated gamble but not the last-fixated reason predicted participants' choices. Third, a comparison of data obtained with eye tracking and data obtained with verbal protocols from a previous study showed a large degree of convergence regarding the process of risky choice. Together these findings tend to support dimensional decision strategies such as the priority heuristic. |
D. J. Bridge; Joel L. Voss Hippocampal binding of novel information with dominant memory traces can support both memory stability and change Journal Article In: Journal of Neuroscience, vol. 34, no. 6, pp. 2203–2213, 2014. @article{Bridge2014, Memory stability and change are considered opposite outcomes. We tested the counterintuitive notion that both depend on one process: hippocampal binding of memory features to associatively novel information, or associative novelty binding (ANB). Building on the idea that dominant memory features, or “traces,” are most susceptible to modification, we hypothesized that ANB would selectively involve dominant traces. Therefore, memory stability versus change should depend on whether the currently dominant trace is old versus updated; in either case, novel information will be bound with it, causing either maintenance (when old) or change (when updated). People in our experiment studied objects at locations within scenes (contexts). During reactivation in a new context, subjects moved studied objects to new locations either via active location recall or by passively dragging objects to predetermined locations. After active reactivation, the new object location became dominant in memory, whereas after passive reactivation, the old object location maintained dominance. In both cases, hippocampal ANB bound the currently dominant object-location memory with a context with which it was not paired previously (i.e., associatively novel). Stability occurred in the passive condition when ANB united the dominant original location trace with an associatively novel newer context. Change occurred in the active condition when ANB united the dominant updated object location with an associatively novel and older context. Hippocampal ANB of the currently dominant trace with associatively novel contextual information thus provides a single mechanism to support memory stability and change, with shifts in trace dominance during reactivation dictating the outcome. |
Matthew W. Bridgman; Warren S. Brown; Michael L. Spezio; Matthew K. Leonard; Ralph Adolphs; Lynn K. Paul Facial emotion recognition in agenesis of the corpus callosum Journal Article In: Journal of Neurodevelopmental Disorders, vol. 6, pp. 1–14, 2014. @article{Bridgman2014, BACKGROUND: Impaired social functioning is a common symptom of individuals with developmental disruptions in callosal connectivity. Among these developmental conditions, agenesis of the corpus callosum provides the most extreme and clearly identifiable example of callosal disconnection. To date, deficits in nonliteral language comprehension, humor, theory of mind, and social reasoning have been documented in agenesis of the corpus callosum. Here, we examined a basic social ability as yet not investigated in this population: recognition of facial emotion and its association with social gaze. METHODS: Nine individuals with callosal agenesis and nine matched controls completed four tasks involving emotional faces: emotion recognition from upright and inverted faces, gender recognition, and passive viewing. Eye-tracking data were collected concurrently on all four tasks and analyzed according to designated facial regions of interest. RESULTS: Individuals with callosal agenesis exhibited impairments in recognizing emotions from upright faces, in particular lower accuracy for fear and anger, and these impairments were directly associated with diminished attention to the eye region. The callosal agenesis group exhibited greater consistency in emotion recognition across conditions (upright vs. inverted), with poorest performance for fear identification in both conditions. The callosal agenesis group also had atypical facial scanning (lower fractional dwell time in the eye region) during gender naming and passive viewing of faces, but they did not differ from controls on gender naming performance. The pattern of results did not differ when taking into account full-scale intelligence quotient or presence of autism spectrum symptoms. CONCLUSIONS: Agenesis of the corpus callosum results in a pattern of atypical facial scanning characterized by diminished attention to the eyes. This pattern suggests that reduced callosal connectivity may contribute to the development and maintenance of emotion processing deficits involving reduced attention to others' eyes. |
Allison E. Britt; Daniel Mirman; Sergey A. Kornilov; James S. Magnuson Effect of repetition proportion on language-driven anticipatory eye movements Journal Article In: Acta Psychologica, vol. 145, no. 1, pp. 128–138, 2014. @article{Britt2014, Previous masked priming research in word recognition has demonstrated that repetition priming is influenced by experiment-wise information structure, such as proportion of target repetition. Research using naturalistic tasks and eye-tracking has shown that people use linguistic knowledge to anticipate upcoming words. We examined whether the proportion of target repetition within an experiment can have a similar effect on anticipatory eye movements. We used a word-to-picture matching task (i.e., the visual world paradigm) with target repetition proportion carefully controlled. Participants' eye movements were tracked starting when the pictures appeared, one second prior to the onset of the target word. Targets repeated from the previous trial were fixated more than other items during this preview period when target repetition proportion was high and less than other items when target repetition proportion was low. These results indicate that linguistic anticipation can be driven by short-term within-experiment trial structure, with implications for the generalization of priming effects, the bases of anticipatory eye movements, and experiment design. |
Jon Brock; Kate Nation The hardest butter to button: Immediate context effects in spoken word identification Journal Article In: Quarterly Journal of Experimental Psychology, vol. 67, no. 1, pp. 114–123, 2014. @article{Brock2014, According to some theories, the context in which a spoken word is heard has no impact on the earliest stages of word identification. This view has been challenged by recent studies indicating an interactive effect of context and acoustic similarity on language-mediated eye movements. However, an alternative explanation for these results is that participants looked less at acoustically similar objects in constraining contexts simply because they were looking more at other objects that were cued by the context. The current study addressed this concern whilst providing a much finer grained analysis of the temporal evolution of context effects. Thirty-two adults listened to sentences while viewing a computer display showing four objects. As expected, shortly after the onset of a target word (e.g., "button") in a neutral context, participants saccaded preferentially towards a cohort competitor of the word (e.g., butter). This effect was significantly reduced when the preceding verb made the competitor an unlikely referent (e.g., "Sam fastened the button"), even though there were no other contextually congruent objects in the display. Moreover, the time-course of these two effects was identical to within approximately 30 ms, indicating that certain forms of contextual information can have a near-immediate effect on word identification. |
Robert D. Gordon Saccade latency reveals episodic representation of object color Journal Article In: Attention, Perception, and Psychophysics, vol. 76, no. 6, pp. 1765–1777, 2014. @article{Gordon2014, While previous studies suggest that identity, but not color, plays a role in episodic object representation, such studies have typically used tasks in which only identity is relevant, raising the possibility that the results reflect task demands, rather than the general principles that underlie ob- ject representation. In the present study, participants viewed a preview display containing one (Experiments 1 and 2)ortwo (Experiment 3) letters, then viewed a target display containing a single letter, in either the same or a different location. Participants executed an immediate saccade to fixate the tar- get; saccade latency served as the dependent variable. In all experiments, saccade latencies were longer to fixate a target appearing in its previewed location, consistent with a bias to attend to new objects rather than to objects for which episodic representations are being maintained in visual working mem- ory. The results ofExperiment 3 further demonstrate, howev- er, that changing target color eliminates these latency differ- ences. The results suggest that color and identity are part of episodic representation even when not task relevant and that examining biases in saccade execution may be a useful ap- proach to studying episodic representation. |
Andrei Gorea; Delphine Rider; Qing Yang A unified comparison of stimulus-driven, endogenous mandatory and 'free choice' saccades Journal Article In: PLoS ONE, vol. 9, no. 2, pp. e88990, 2014. @article{Gorea2014, It has been claimed that saccades arising from the three saccade triggering modes-stimulus-driven, endogenous mandatory and 'free choice'-are driven by distinct mechanisms. We tested this claim by instructing observers to saccade from a white or black fixation disc to a same polarity (white or black) disc flashed for 100 or 200 ms presented either alone (Exo), or together with an opposite (Endo) or same (EndoFC) polarity disc (blocked and mixed sessions). Target(s) and distractor were presented at three inter-stimulus intervals (ISIs) relative to the fixation offset (ISI: -200, 0, +200 ms) and were displayed at random locations within a 4°-to-6° eccentricity range. The statistical analysis showed a global saccade triggering mode effect on saccade reaction times (SRTs) with Endo and EndoFC SRTs longer by about 27 ms than Exo-triggered ones but no effect for the Endo-EndoFC comparison. SRTs depended on both ISI (the "gap-effect"), and target duration. Bimodal best fits of the SRT-distributions were found in 65% of cases with their count not different across the three triggering modes. Percentages of saccades in the 'fast' and 'slow' ranges of bimodal fits did not depend on the triggering modes either. Bimodality tests failed to assert a significant difference between these modes. An analysis of the timing of a putative inhibition by the distractor (Endo) or by the duplicated target (EndoFC) yielded no significant difference between Endo and EndoFC saccades but showed a significant shortening with ISI similar to the SRT shortening suggesting that the distractor-target mutual inhibition is itself inhibited by 'fixation' neurons. While other experimental paradigms may well sustain claims of distinct mechanisms subtending the three saccade triggering modes, as here defined reflexive and voluntary saccades appear to differ primarily in the effectiveness with which inhibitory processes slow down the initial fast rise of the saccade triggering signal. |
Harriet Goschy; A. Isabel Koch; Hermann J. Müller; Michael Zehetleitner Early top-down control over saccadic target selection: Evidence from a systematic salience difference manipulation Journal Article In: Attention, Perception, and Psychophysics, vol. 76, no. 2, pp. 367–382, 2014. @article{Goschy2014, Previous research on the contribution of top-down control to saccadic target selection has suggested that eye movements, especially short-latency saccades, are primarily salience driven. The present study was designed to systematically examine top-down influences as a function of time and relative salience difference between target and distractor. Observers performed a saccadic selection task, requiring them to make an eye movement to an orientation-defined target, while ignoring a color-defined distractor. The salience of the distractor was varied (five levels), permitting the percentage of target and distractor fixations to be analyzed as a function of the salience difference between the target and distractor. This analysis revealed the same pattern of results for both the overall and the short-latency saccades: When the target and distractor were of comparable salience, the vast majority of saccades went directly to the target; even distractors somewhat more salient than the target led to significantly fewer distractor, as compared with target, fixations. To quantify the amount of top-down control applied, we estimated the point of equal selection probability for the target and distractor. Analyses of these estimates revealed that, to be selected with equal probability to the target, a distractor had to have a considerably greater bottom-up salience, as compared with the target. This difference suggests a strong contribution of top-down control to saccadic target selection-even for the earliest saccades. |
Alina Graf; Richard A. Andersen Inferring eye position from populations of lateral intraparietal neurons Journal Article In: eLife, vol. 2014, no. 3, pp. 1–13, 2014. @article{Graf2014, Understanding how the brain computes eye position is essential to unraveling high- level visual functions such as eye movement planning, coordinate transformations and stability of spatial awareness. The lateral intraparietal area (LIP) is essential for this process. However, despite decades of research, its contribution to the eye position signal remains controversial. LIP neurons have recently been reported to inaccurately represent eye position during a saccadic eye movement, and to be too slow to support a role in high-level visual functions. We addressed this issue by predicting eye position and saccade direction from the responses of populations of LIP neurons. We found that both signals were accurately predicted before, during and after a saccade. Also, the dynamics of these signals support their contribution to visual functions. These findings provide a principled understanding of the coding of information in populations of neurons within an important node of the cortical network for visual-motor behaviors. |
Michael J. Gray; Annabelle Blangero; James P. Herman; Josh Wallman; Mark R. Harwood Adaptation of naturally paced saccades Journal Article In: Journal of Neurophysiology, vol. 111, no. 11, pp. 2343–2354, 2014. @article{Gray2014, In the natural environment, humans make saccades almost continuously. In many eye movement experiments, however, observers are required to fixate for unnaturally long periods of time. The resulting long and monotonous experimental sessions can become especially problematic when collecting data in a clinical setting, where time can be scarce and subjects easily fatigued. With this in mind, we tested whether the well-studied motor learning process of saccade adaptation could be induced with a dramatically shortened intertrial interval. Observers made saccades to targets that stepped left or right either ∼250 ms or ∼1,600 ms after the saccade landed. In experiment I, we tested baseline saccade parameters to four different target amplitudes (5°, 10°, 15°, and 20°) in the two timing settings. In experiments II and III, we adapted 10° saccades via 2° intrasaccadic steps either backwards or forwards, respectively. Seven subjects performed eight separate adaptation sessions (2 intertrial timings × 2 adaptation direction × 2 session trial lengths). Adaptation proceeded remarkably similarly in both timing conditions across the multiple sessions. In the faster-paced sessions, robust adaptation was achieved in under 2 min, demonstrating the efficacy of our approach to streamlining saccade adaptation experiments. Although saccade amplitudes were similar between conditions, the faster-paced condition unexpectedly resulted in significantly higher peak velocities in all subjects. This surprising finding demonstrates that the stereotyped "main sequence" relationship between saccade amplitude and peak velocity is not as fixed as originally thought. |
Jennifer L. Greenberg; Lillian Reuman; Andrea S. Hartmann; Irina Kasarskis; Sabine Wilhelm Visual hot spots: An eye tracking study of attention bias in body dysmorphic disorder Journal Article In: Journal of Psychiatric Research, vol. 57, no. 1, pp. 125–132, 2014. @article{Greenberg2014, Attentional biases have been implicated in the development and maintenance of BDD. In particular, a visual attention bias toward one's unattractive features and others' attractive features (negative bias), might underlie BDD symptoms. Healthy individuals typically pay more attention to others' unattractive and their own attractive features (positive bias). This study used eye tracking to examine visual attention in individuals with BDD relative to healthy controls (HC). We also explored the role of avoidance in attention bias. Participants with BDD and primary face/head concerns ( n = 19) and HC ( n = 20) completed computerized tasks and questionnaires. Eye movement data (i.e., fixations, dwell time) were recorded while participants viewed images of their own and a control face (selected for average attractiveness and neutral expression). Participants rated distress and perceived most and least attractive features of their own and another face. BDD participants demonstrated a negative mean total bias score compared to HC (fixation: p = 0.24; dwell: p = 0.08). Age (fixation: p = 0.006; dwell: p = 0.03) and gender (fixation: p = 0.03; dwell: p = 0.03) moderated the relationship. Avoidance was associated with a positive bias in BDD. Results suggest individuals with BDD overfocus on negative attributes, a potential factor in the disorder's etiology and maintenance. Conversely, HC had a more balanced focus on their traits. Elucidating the role of attention bias could help to identify risk and maintenance factors in BDD. |
Harold H. Greene; James M. Brown; Barry Dauphin When do you look where you look? A visual field asymmetry Journal Article In: Vision Research, vol. 102, pp. 33–40, 2014. @article{Greene2014, Pre-saccadic fixation durations associated with saccades directed in different directions were compared in three endogenous-attention oriented saccadic scanning tasks (i.e. visual search and scene viewing). Pre-saccadic fixation durations were consistently briefer before the execution of upward saccades, than downward saccades. Saccades also had a higher probability of being directed upwards than downwards. Pre-saccadic fixation durations were symmetric and longer for horizontally-directed saccades. The vertical visual field asymmetry in pre-saccadic fixation durations reflects an influence of factors not directly related to currently fixated elements. The ability to predict pre-saccadic fixation durations is important for computational modelling of real-time saccadic scanning, and the findings make a case for including directional constraints in computational modelling of when the eyes move. |
Xiao-Jing Gu; Ming Hu; Bing Li; Xin-Tian Hu The role of contrast adaptation in saccadic suppression in humans Journal Article In: PLoS ONE, vol. 9, no. 1, pp. e86542, 2014. @article{Gu2014, The idea of retinal and ex-retinal sources of saccadic suppression has long been established in previous studies. However, how they are implemented in local circuit remains unknown. Researchers have suggested that saccadic suppression was probably achieved by contrast gain control, but this possibility has never been directly tested. In this study, we manipulated contrast gain control by contrast-adapting observers with sinusoidal gratings of different contrasts. Presaccadic and fixational contrast thresholds were measured and compared to give estimates of saccadic suppression at different adaptation states. Our results reconfirmed the selective saccadic suppression in achromatic condition, and further showed that, achromatic saccadic suppression diminished as contrast adaptation was accentuated, whereas no significant chromatic saccadic suppression was induced by greater contrast adaptation. Our data provided evidence for the involvement of contrast gain control in saccadic suppression in achromatic channel. We also discussed how the negative correlation between contrast adaptation and saccadic suppression could be interpreted with contrast gain control. |
Katherine Guérard; Jean Saint-Aubin; Marilyne Maltais; Hugo Lavoie The role of verbal memory in regressions during reading is modulated by the target word's recency in memory Journal Article In: Memory & Cognition, vol. 42, no. 7, pp. 1155–1170, 2014. @article{Guerard2014, During reading, a number of eye movements are made backward, on words that have already been read. Recent evidence suggests that such eye movements, called regressions, are guided by memory. Several studies point to the role of spatial memory, but evidence for the role of verbal memory is more limited. In the present study, we examined the factors that modulate the role of verbal memory in regressions. Participants were required to make regressions on target words located in sentences displayed on one or two lines. Verbal interference was shown to affect regressions, but only when participants executed a regression on a word located in the first part of the sentence, irrespective of the number of lines on which the sentence was displayed. Experiments 2 and 3 showed that the effect of verbal interference on words located in the first part of the sentence disappeared when participants initiated the regression from the middle of the sentence. Our results suggest that verbal memory is recruited to guide regressions, but only for words read a longer time ago. |
Lesya Y. Ganushchak; Agnieszka E. Konopka; Yiya Chen What the eyes say about planning of focused referents during sentence formulation: A cross-linguistic investigation Journal Article In: Frontiers in Psychology, vol. 5, pp. 1124, 2014. @article{Ganushchak2014, This study investigated how sentence formulation is influenced by a preceding discourse context. In two eye-tracking experiments, participants described pictures of two-character transitive events in Dutch (Experiment 1) and Chinese (Experiment 2). Focus was manipulated by presenting questions before each picture. In the Neutral condition, participants first heard "What is happening here?" In the Object or Subject Focus conditions, the questions asked about the Object or Subject character (What is the policeman stopping? Who is stopping the truck?). The target response was the same in all conditions (The policeman is stopping the truck). In both experiments, sentence formulation in the Neutral condition showed the expected pattern of speakers fixating the subject character (policeman) before the object character (truck). In contrast, in the focus conditions speakers rapidly directed their gaze preferentially only to the character they needed to encode to answer the question (the new, or focused, character). The timing of gaze shifts to the new character varied by language group (Dutch vs. Chinese): shifts to the new character occurred earlier when information in the question can be repeated in the response with the same syntactic structure (in Chinese but not in Dutch). The results show that discourse affects the timecourse of linguistic formulation in simple sentences and that these effects can be modulated by language-specific linguistic structures such as parallels in the syntax of questions and declarative sentences. |
Xiao Gao; Xiao Deng; Jia Yang; Shuang Liang; Jie Liu; Hong Chen Eyes on the bodies: An eye tracking study on deployment of visual attention among females with body dissatisfaction Journal Article In: Eating Behaviors, vol. 15, no. 4, pp. 540–549, 2014. @article{Gao2014, Visual attentional bias has important functions during the appearance social comparisons. However, for the limitations of experimental paradigms or analysis methods in previous studies, the time course of attentional bias to thin and fat body images among women with body dissatisfaction (BD) has still been unclear. In using free reviewing task combined with eye movement tracking, and based on event-related analyses of the critical first eye movement events, as well as epoch-related analyses of gaze durations, the current study investigated different attentional bias components to body shape/part images during 15. s presentation time among 34 high BD and 34 non-BD young women. In comparison to the controls, women with BD showed sustained maintenance biases on thin and fat body images during both early automatic and late strategic processing stages. This study highlights a clear need for research on the dynamics of attentional biases related to body image and eating disturbances. |
Stephan Geuter; Matthias Gamer; Selim Onat; Christian Büchel Parametric trial-by-trial prediction of pain by easily available physiological measures Journal Article In: Pain, vol. 155, no. 5, pp. 994–1001, 2014. @article{Geuter2014, Pain is commonly assessed by subjective reports on rating scales. However, in many experimental and clinical settings, an additional, objective indicator of pain is desirable. In order to identify an objective, parametric signature of pain intensity that is predictive at the individual stimulus level across subjects, we recorded skin conductance and pupil diameter responses to heat pain stimuli of different durations and temperatures in 34 healthy subjects. The temporal profiles of trial-wise physiological responses were characterized by component scores obtained from principal component analysis. These component scores were then used as predictors in a linear regression analysis, resulting in accurate pain predictions for individual trials. Using the temporal information encoded in the principal component scores explained the data better than prediction by a single summary statistic (ie, maximum amplitude). These results indicate that perceived pain is best reflected by the temporal dynamics of autonomic responses. Application of the regression model to an independent data set of 20 subjects resulted in a very good prediction of the pain ratings demonstrating the generalizability of the identified temporal pattern. Utilizing the readily available temporal information from skin conductance and pupil diameter responses thus allows parametric prediction of pain in human subjects. |
Fatema F. Ghasia; Deepak Gulati; Edward L. Westbrook; Aasef G. Shaikh Viewing condition dependence of the gaze-evoked nystagmus in Arnold Chiari type 1 malformation Journal Article In: Journal of the Neurological Sciences, vol. 339, no. 1-2, pp. 134–139, 2014. @article{Ghasia2014, Saccadic eye movements rapidly shift gaze to the target of interest. Once the eyes reach a given target, the brainstem ocular motor integrator utilizes feedback from various sources to assure steady gaze. One of such sources is cerebellum whose lesion can impair neural integration leading to gaze-evoked nystagmus. The gaze evoked nystagmus is characterized by drifts moving the eyes away from the target and a null position where the drifts are absent. The extent of impairment in the neural integration for two opposite eccentricities might determine the location of the null position. Eye in the orbit position might also determine the location of the null. We report this phenomenon in a patient with Arnold Chiari type 1 malformation who had intermittent esotropia and horizontal gaze-evoked nystagmus with a shift in the null position. During binocular viewing, the null was shifted to the right. During monocular viewing, when the eye under cover drifted nasally (secondary to the esotropia), the null of the gaze-evoked nystagmus reorganized toward the center. We speculate that the output of the neural integrator is altered from the bilateral conflicting eye in the orbit position secondary to the strabismus. This could possibly explain the reorganization of the location of the null position. |
Fatema F. Ghasia; Aasef G. Shaikh Source of high-frequency oscillations in oblique saccade trajectory Journal Article In: Experimental Eye Research, vol. 121, pp. 5–10, 2014. @article{Ghasia2014a, Most common eye movements, oblique saccades, feature rapid velocity, precise amplitude, but curved trajectory that is variable from trial-to-trial. In addition to curvature and inter-trial variability, the oblique saccade trajectory also features high-frequency oscillations. A number of studies proposed the physiological basis of the curvature and inter-trial variability of the oblique saccade trajectory, but kinematic characteristics of high-frequency oscillations are yet to be examined. We measured such oscillations and compared their properties with orthogonal pure horizontal and pure vertical oscillations generated during pure vertical and pure horizontal saccades, respectively. We found that the frequency of oscillations during oblique saccades ranged between 15 and 40Hz, consistent with the frequency of orthogonal saccadic oscillations during pure horizontal or pure vertical saccades. We also found that the amplitude of oblique saccade oscillations was larger than pure horizontal and pure vertical saccadic oscillations. These results suggest that the superimposed high-frequency sinusoidal oscillations upon the oblique saccade trajectory represent reverberations of disinhibited circuit of reciprocally innervated horizontal and vertical burst generators. |
Wei He; Jon Brock; Blake W. Johnson Face-sensitive brain responses measured from a four-year-old child with a custom-sized child MEG system Journal Article In: Journal of Neuroscience Methods, vol. 222, pp. 213–217, 2014. @article{He2014, Background: Previous magnetoencephalography (MEG) studies have failed to find a facesensitive, brain response-M170 in children. If this is the case, this suggests that the developmental trajectory of the M170 is different from that of its electrical equivalent, the N170. We investigated the alternative possibility that the child M170 may not be detectable in conventional adult-sized MEG systems. New method: Brain responses to pictures of faces and well controlled stimuli were measured from the same four-year-old child with a custom child MEG system and an adult-sized MEG system. Results: The goodness of fit of the child's head was about the same over the occipital head surface in both systems, but was much worse over all other parts of the head surface in the adult MEG system compared to the child MEG system. The face-sensitive M170 was measured from the child in both MEG systems, but was larger in amplitude, clearer in morphology, and had a more accurate source localization when measured in the child MEG system. Comparison with existing method: The custom-sized child MEG system is superior for measuring the face-sensitive M170 brain response in children than the conventional adult MEG system. Conclusions: The present results show that the face-sensitive M170 brain response can be elicited in a four-year-old child. This provides new evidence for early maturation of face processing brain mechanisms in humans, and offers new opportunities for the study of neurodevelopmental disorders that show atypical face processing capabilities, such as autism spectrum disorder. |
Kristin J. Heaton; Alexis L. Maule; Jun Maruta; Elisabeth M. Kryskow; Jamshid Ghajar Attention and visual tracking degradation during acute sleep deprivation in a military sample Journal Article In: Aviation Space and Environmental Medicine, vol. 85, no. 5, pp. 497–503, 2014. @article{Heaton2014, Background: Fatigue due to sleep restriction places individuals at elevated risk for accidents, degraded health, and impaired physical and mental performance. Early detection of fatigue-related performance decrements is an important component of injury prevention and can help to ensure optimal performance and mission readiness. This study used a predictive visual tracking task and a computer-based measure of attention to characterize fatigue-related attention decrements in healthy Army personnel during acute sleep deprivation. Methods: Serving as subjects in this laboratory-based study were 87 male and female service members between the ages of 18 and 50 with no history of brain injury with loss of consciousness, substance abuse, or significant psychiatric or neurologic diagnoses. Subjects underwent 26 h of sleep deprivation, during which eye movement measures from a continuous circular visual tracking task and attention measures (reaction time, accuracy) from the Attention Network Test (ANT) were collected at baseline, 20 h awake, and between 24 to 26 h awake. Results: Increases in the variability of gaze positional errors (46-47%), as well as reaction time-based ANT measures (9-65%), were observed across 26 h of sleep deprivation. Accuracy of ANT responses declined across this same period (11%). Discussion: Performance measures of predictive visual tracking accurately reflect impaired attention due to acute sleep deprivation and provide a promising approach for assessing readiness in personnel serving in diverse occupational areas, including flight and ground support crews. |
Jessica Heeman; Jan Theeuwes; Stefan Van der Stigchel The time course of top-down control on saccade averaging Journal Article In: Vision Research, vol. 100, pp. 29–37, 2014. @article{Heeman2014, When objects in a visual scene are positioned in close proximity, eye movements to these objects tend to land at an intermediate location between the objects (i.e. the global effect). This effect is most pronounced for short latency saccades and is therefore believed to be reflexive and dominantly controlled by bottom-up information. At longer latencies this effect can be modulated by top-down factors. The current study established the time course at which top-down information starts to have an influence on bottom-up averaging. In a standard global effect task two peripheral stimuli (a red and a green abrupt onset) were positioned within an angular distance of 20°. In the condition in which observers received no specific target instruction, the eyes landed in between the red and green element establishing the classic global effect. However, when observers were instructed to make a saccade to the red element during a whole block or when the target color varied from trial-to-trial (red or green), a clear effect of the target instruction on the accuracy of the landing position of the primary saccade was found. With increasing saccade latencies, the eyes landed closer to the instructed target. Crucially, however, this effect was even seen for the shortest saccade latencies (as early as 200ms), suggesting that saccade averaging is affected early on by top-down processes. |
Benedetta Heimler; Francesco Pavani; Mieke Donk; Wieske Zoest Stimulus-and goal-driven control of eye movements: Action videogame players are faster but not better Journal Article In: Attention, Perception, and Psychophysics, vol. 76, no. 8, pp. 2398–2412, 2014. @article{Heimler2014, Action videogame players (AVGPs) have been shown to outperform nongamers (NVGPs) in covert visual attention tasks. These advantages have been attributed to improved top-down control in this population. The time course of visual selection, which permits researchers to highlight when top-down strategies start to control performance, has rarely been investigated in AVGPs. Here, we addressed specifically this issue through an oculomotor additional-singleton paradigm. Participants were instructed to make a saccadic eye movement to a unique orientation singleton. The target was presented among homogeneous nontargets and one additional orientation singleton that was more, equally, or less salient than the target. Saliency was manipulated in the color dimension. Our results showed similar patterns of performance for both AVGPs and NVGPs: Fast-initiated saccades were saliency-driven, whereas later-initiated saccades were more goal-driven. However, although AVGPs were faster than NVGPs, they were also less accurate. Importantly, a multinomial model applied to the data revealed comparable underlying saliency-driven and goal-driven functions for the two groups. Taken together, the observed differences in performance are compatible with the presence of a lower decision bound for releasing saccades in AVGPs than in NVGPs, in the context of comparable temporal interplay between the underlying attentional mechanisms. In sum, the present findings show that in both AVGPs and NVGPs, the implementation of top-down control in visual selection takes time to come about, and they argue against the idea of a general enhancement of top-down control in AVGPs. |
Nils Heise; Ulrich Ansorge The roles of scene priming and location priming in object-scene consistency effects Journal Article In: Frontiers in Psychology, vol. 5, pp. 520, 2014. @article{Heise2014, Presenting consistent objects in scenes facilitates object recognition as compared to inconsistent objects. Yet the mechanisms by which scenes influence object recognition are still not understood. According to one theory, consistent scenes facilitate visual search for objects at expected places. Here, we investigated two predictions following from this theory: If visual search is responsible for consistency effects, consistency effects could be weaker (1) with better-primed than less-primed object locations, and (2) with less-primed than better-primed scenes. In Experiments 1 and 2, locations of objects were varied within a scene to a different degree (one, two, or four possible locations). In addition, object-scene consistency was studied as a function of progressive numbers of repetitions of the backgrounds. Because repeating locations and backgrounds could facilitate visual search for objects, these repetitions might alter the object-scene consistency effect by lowering of location uncertainty. Although we find evidence for a significant consistency effect, we find no clear support for impacts of scene priming or location priming on the size of the consistency effect. Additionally, we find evidence that the consistency effect is dependent on the eccentricity of the target objects. These results point to only small influences of priming to object-scene consistency effects but all-in-all the findings can be reconciled with a visual-search explanation of the consistency effect. |
Karen S. Helfer; Adrian Staub Competing speech perception in older and younger adults: Behavioral and eye-movement evidence Journal Article In: Ear & Hearing, vol. 35, no. 2, pp. 161–170, 2014. @article{Helfer2014, OBJECTIVES: The purpose of this study was to examine eye-movement patterns in older and younger adults to identify differences in how they respond to both to-be-attended and to-be-ignored speech. DESIGN: The study described in this article used an eye-tracking paradigm to provide insight into the factors underlying competing speech understanding in older (n = 23) and younger (n = 22) listeners. Participants attended to a sentence presented in one ear and were instructed to click on a visually displayed word that was heard in that ear while their eye movements were monitored. A foil word also was shown on the screen. Either no sound, steady state noise, or competing speech was presented to the other ear. RESULTS: Comparisons between younger and older listeners on all three types of indicators measured in this study (percent correct, response time, and eye movement patterns) demonstrated that older adults were more greatly affected by competing speech than were younger adults. Differences between the groups could not be attributed to the presence of hearing loss in the older participants, as performance for all subjects was at ceiling in quiet and none of the performance metrics was significantly associated with degree of hearing loss. CONCLUSIONS: Results of this study support the idea that age-related changes other than lack of audibility or susceptibility to energetic masking negatively affect the ability to understand speech in the presence of a competing message. |
Randolph F. Helfrich; Hannah Knepper; Guido Nolte; Daniel Strüber; Stefan Rach; Christoph S. Herrmann; Till R. Schneider; Andreas K. Engel Selective modulation of interhemispheric functional connectivity by HD-tACS shapes perception Journal Article In: PLoS Biology, vol. 12, no. 12, pp. 1–15, 2014. @article{Helfrich2014, Oscillatory neuronal synchronization between cortical areas has been suggested to constitute a flexible mechanism to coordinate information flow in the human cerebral cortex. However, it remains unclear whether synchronized neuronal activity merely represents an epiphenomenon or whether it is causally involved in the selective gating of information. Here, we combined bilateral high-density transcranial alternating current stimulation (HD-tACS) at 40 Hz with simultaneous electroencephalographic (EEG) recordings to study immediate electrophysiological effects during the selective entrainment of oscillatory gamma-band signatures. We found that interhemispheric functional connectivity was modulated in a predictable, phase-specific way: In-phase stimulation enhanced synchronization, anti-phase stimulation impaired functional coupling. Perceptual correlates of these connectivity changes were found in an ambiguous motion task, which strongly support the functional relevance of long-range neuronal coupling. Additionally, our results revealed a decrease in oscillatory alpha power in response to the entrainment of gamma band signatures. This finding provides causal evidence for the antagonistic role of alpha and gamma oscillations in the parieto-occipital cortex and confirms that the observed gamma band modulations were physiological in nature. Our results demonstrate that synchronized cortical network activity across several spatiotemporal scales is essential for conscious perception and cognition. |
Daphna Heller; Craig G. Chambers Would a blue kite by any other name be just as blue? Effects of descriptive choices on subsequent referential behavior Journal Article In: Journal of Memory and Language, vol. 70, no. 1, pp. 53–67, 2014. @article{Heller2014, Using objects that contrast along multiple dimensions, we examined how the earlier description of an object using one dimension (size/color) influences reference to as-yet unmentioned objects, and how this depends on whether the two objects contrast with each other (i.e., whether they belong to the same nominal category). The dimensions of size and color were used because of their different sensitivity, with size adjectives being more closely tied to the presence of a contrasting object from the same category in the situational context. Experiment 1 elicited speakers' descriptions for an object following an earlier description of another object, and Experiment 2 investigated the real-time comprehension of the second description in a two-utterance sequence. Although the priming of linguistic forms may play a role in explaining some of the observed referential patterns, the full set of data suggests that precedence effects in referential descriptions are best explained in terms of a representation that maps those forms onto a mental representation of entities, namely, a discourse model that encodes relationships between entities. The results also highlight how color and size adjectives are processed differently from the earliest moments in comprehension. |
Andrea Helo; Sebastian Pannasch; Louah Sirri; Pia Rämä The maturation of eye movement behavior: Scene viewing characteristics in children and adults Journal Article In: Vision Research, vol. 103, pp. 83–91, 2014. @article{Helo2014, While the close link between eye movements and visual attention has often been demonstrated, recently distinct attentional modes have been associated with specific eye movement patterns. The ambient mode-serving the localization of objects and dominating early scene inspection-is expressed by short fixations and large saccade amplitudes. The focal mode-associated with the identification of object details and dominating later stages of scene exploration-is indicated by longer fixations embedded in short saccades. The relationship between these processing modes and eye movement characteristics has so far only been examined in adults. While studies in children revealed a maturation of oculomotor behavior up to adolescence, developmental aspects of the processing modes are still unknown. Here we explored these mechanisms by comparing eye movements during the inspection of naturalistic scenes. Therefore, gaze behavior from adults and children in four different age groups (2, 4-6, 6-8, 8-10. years old) was examined. We found a general effect of age, revealing that with age fixation durations decrease and saccade amplitudes increase. However, in all age groups fixations were shorter and saccades were longer at the beginning of scene inspection but fixations became longer and saccades became shorter over time. While saliency influenced eye guidance in the two youngest groups over the full inspection period, for the older groups this influence was found only at the beginning of scene inspection. The results reveal indications for ambient and focal processing strategies for as early as 2 years of age. |
Kasey S. Hemington; James N. Reynolds In: Clinical Neurophysiology, vol. 125, no. 12, pp. 2364–2371, 2014. @article{Hemington2014, Objective: Children with Fetal Alcohol Spectrum Disorder (FASD) exhibit cognitive deficits that can be probed using eye movement tasks. We employed a recently developed, single-sensor electroencephalographic (EEG) recording device in measuring EEG activity during the performance of an eye movement task probing working memory in this population. Methods: Children with FASD (n= 18) and typically developing children (n= 19) performed a memory-guided saccade task requiring the participant to remember the spatial location of one, two or three stimuli. We hypothesized that children with FASD would (i) exhibit performance deficits, particularly at greater mnemonic loads; and (ii) display differences in theta (4-8 Hz) and alpha (8-12 Hz) frequency band power compared with controls. Results: Children with FASD failed to perform the task correctly more often than controls when presented with two or three stimuli, and demonstrated related reductions in alpha and theta power. Conclusion: These data suggest that the memory-guided task is sensitive to working memory deficits in children with FASD. Significance: Simultaneous recording of EEG activity suggest differing patterns of underlying neural recruitment in the clinical group, consistent with previous literature indicating more cognitive resources are required by children with FASD in order to complete complex tasks correctly. |
John M. Henderson; Wonil Choi; Steven G. Luke Morphology of primary visual cortex predicts individual differences in fixation duration during text reading Journal Article In: Journal of Cognitive Neuroscience, vol. 26, no. 12, pp. 2880–2888, 2014. @article{Henderson2014a, In skilled reading, fixations are brief periods of time in which the eyes settle on words. E-Z Reader, a computational model of dynamic reading, posits that fixation durations are under realtime control of lexical processing. Lexical processing, in turn, requires efficient visual encoding. Here we tested the hypothesis that individual differences in fixation durations are related to individual differences in the efficiency of early visual encoding. To test this hypothesis, we recorded participantsʼ eye movements during reading. We then examined individual differences in fixation duration distributions as a function of individual differences in the morphology of primary visual cortex measured from MRI scans. The results showed that greater gray matter surface area and volume in visual cortex predicted shorter and less variable fixation durations in reading. These results suggest that individual differences in eye movements during skilled reading are related to initial visual encoding, consistent with models such as E-Z Reader that emphasize lexical control over fixation time. |