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2009 |
Oleg Špakov; Päivi Majaranta Scrollable keyboards for casual eye typing Journal Article In: PsychNology Journal, vol. 7, no. 2, pp. 159–173, 2009. @article{Spakov2009,In eye typing, a full on-screen keyboard often takes a lot of space because the inaccuracy in eye tracking requires big keys. We propose “scrollable keyboards” where one or more rows are hidden to save space. Results from an experiment with 8 expert participants show that the typing speed reduced by 51.4% for a 1-row keyboard and 25.3% for a 2-row keyboard compared to a full (3-row) QWERTY. By optimizing the keyboard layout according to letter- to-letter probabilities we were able to reduce the scroll button usage, which further increased the typing speed from 7.26 wpm (QWERTY) to 8.86 wpm (optimized layout) on the 1-row keyboard, and from 11.17 wpm to 12.18 wpm on the 2-row keyboard, respectively |
Siddharth Srivastava; Guy A. Orban; Patrick A. De Maziere; Peter Janssen A distinct representation of three-dimensional shape in macaque anterior intraparietal area: Fast, metric, and coarse Journal Article In: Journal of Neuroscience, vol. 29, no. 34, pp. 10613–10626, 2009. @article{Srivastava2009,Differences in the horizontal positions of retinal images—binocular disparity—provide important cues for three-dimensional object recognition and manipulation. We investigated the neural coding ofthree-dimensional shape defined by disparity in anterior intrapari- etal (AIP) area. Robust selectivity for disparity-defined slanted and curved surfaces was observed in a high proportion ofAIP neurons, emerging at relatively short latencies. The large majority of AIP neurons preserved their three-dimensional shape preference over different positions in depth, a hallmark of higher-order disparity selectivity. Yet both stimulus type (concave–convex) and position in depth could be reliably decoded from the AIP responses. The neural coding ofthree-dimensional shape was based on first-order (slanted surfaces) and second-order (curved surfaces) disparity selectivity. Many AIP neurons tolerated the presence ofdisparity discontinuities in the stimulus, but the population ofAIP neurons provided reliable information on the degree ofcurvedness ofthe stimulus. Finally, AIP neurons preserved their three-dimensional shape preference over different positions in the frontoparallel plane. Thus, AIP neurons extract or have access to three-dimensional object information defined by binocular disparity, consistent with previous functional magnetic resonance imaging data. Unlike the known representation ofthree-dimensional shape in inferior temporal cortex, the neural representation in AIP appears to emphasize object parameters required for the planning ofgrasping movements. |
Christian Starzynski; Ralf Engbert Noise-enhanced target discrimination under the influence of fixational eye movements and external noise Journal Article In: Chaos, vol. 19, no. 1, pp. 1–7, 2009. @article{Starzynski2009,Active motor processes are present in many sensory systems to enhance perception. In the human visual system, miniature eye movements are produced involuntarily and unconsciously when we fixate a stationary target. These fixational eye movements represent self-generated noise which serves important perceptual functions. Here we investigate fixational eye movements under the influence of external noise. In a two-choice discrimination task, the target stimulus performed a random walk with varying noise intensity. We observe noise-enhanced discrimination of the target stimulus characterized by a U-shaped curve of manual response times as a function of the diffusion constant of the stimulus. Based on the experiments, we develop a stochastic information-accumulator model for stimulus discrimination in a noisy environment. Our results provide a new explanation for the constructive role of fixational eye movements in visual perception. |
Adrian Staub; Margaret Grant; Charles Clifton; Keith Rayner Phonological typicality does not influence fixation durations in normal reading Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 35, no. 3, pp. 806–814, 2009. @article{Staub2009,Using a word-by-word self-paced reading paradigm, T. A. Farmer, M. H. Christiansen, and P. Monaghan (2006) reported faster reading times for words that are phonologically typical for their syntactic category (i.e., noun or verb) than for words that are phonologically atypical. This result has been taken to suggest that language users are sensitive to subtle relationships between sound and syntactic function and that they make rapid use of this information in comprehension. The present article reports attempts to replicate this result using both eyetracking during normal reading (Experiment 1) and word-by-word self-paced reading (Experiment 2). No hint of a phonological typicality effect emerged on any reading-time measure in Experiment 1, nor did Experiment 2 replicate Farmer et al.'s finding from self-paced reading. Indeed, the differences between condition means were not consistently in the predicted direction, as phonologically atypical verbs were read more quickly than phonologically typical verbs, on most measures. Implications for research on visual word recognition are discussed. |
Stephen V. Shepherd; Jeffrey T. Klein; Robert O. Deaner; Michael L. Platt Mirroring of attention by neurons in macaque parietal cortex Journal Article In: Proceedings of the National Academy of Sciences, vol. 106, no. 23, pp. 9489–9494, 2009. @article{Shepherd2009,Macaques, like humans, rapidly orient their attention in the direction other individuals are looking. Both cortical and subcortical pathways have been proposed as neural mediators of social gaze following, but neither pathway has been characterized electrophysiologically in behaving animals. To address this gap, we recorded the activity of single neurons in the lateral intraparietal area (LIP) of rhesus macaques to determine whether and how this area might contribute to gaze following. A subset of LIP neurons mirrored observed attention by firing both when the subject looked in the preferred direction of the neuron, and when observed monkeys looked in the preferred direction of the neuron, despite the irrelevance of the monkey images to the task. Importantly, the timing of these modulations matched the time course of gaze-following behavior. A second population of neurons was suppressed by social gaze cues, possibly subserving task demands by maintaining fixation on the observed face. These observations suggest that LIP contributes to sharing of observed attention and link mirror representations in parietal cortex to a well studied imitative behavior. |
Heather Sheridan; Eyal M. Reingold; Meredyth Daneman Using puns to study contextual influences on lexical ambiguity resolution: Evidence from eye movements Journal Article In: Psychonomic Bulletin & Review, vol. 16, no. 5, pp. 875–881, 2009. @article{Sheridan2009,Participants' eye movements were monitored while they read sentences containing biased homographs in either a single-meaning context condition that instantiated the subordinate meaning of the homograph without ruling out the dominant meaning (e.g., "The man with a toothache had a crown made by the best dentist in town") or a dual-meaning pun context condition that supported both the subordinate and dominant meanings (e.g., "The king with a toothache had a crown made by the best dentist in town"). In both of these conditions, the homographs were followed by disambiguating material that supported the subordinate meaning and ruled out the dominant meaning. Fixation times on the homograph were longer in the single-meaning condition than in the dual-meaning condition, whereas the reverse pattern was demonstrated for fixation times on the disambiguating region; these effects were observed as early as first-fixation duration. The findings strongly support the reordered access model of lexical ambiguity resolution. |
J. Stephen Higgins; David E. Irwin; Ranxiao Frances Wang; Laura E. Thomas Visual direction constancy across eyeblinks Journal Article In: Attention, Perception, and Psychophysics, vol. 71, no. 7, pp. 1607–1617, 2009. @article{StephenHiggins2009,When a visual target is displaced during a saccade, the perception of its displacement is suppressed. Its movement can usually only be detected if the displacement is quite large. This suppression can be eliminated by introducing a short blank period after the saccade and before the target reappears in a new location. This has been termed the blanking effect and has been attributed to the use of otherwise ignored extraretinal information. We examined whether similar effects occur with eyeblinks and other visual distractions. We found that suppression of displacement perception can also occur due to a blink (both immediately prior to the blink and during the blink), and that introducing a blank period after a blink reduces the displacement suppression in much the same way as after a saccade. The blanking effect does not occur when other visual distractions are used. This provides further support for the conclusion that the blanking effect arises from extraretinal signals about eye position. |
Martin Stritzke; Julia Trommershäuser; Karl R. Gegenfurtner Effects of salience and reward information during saccadic decisions under risk Journal Article In: Journal of the Optical Society of America A, vol. 26, no. 11, pp. B1–B13, 2009. @article{Stritzke2009,Previous work has demonstrated that humans select visuomotor strategies maximizing expected gain during speeded hand movements under risk; see, e.g., [Trends Cogn. Sci. 12, 291 (2008)]; [Glimcher, eds., Neuroeconomics: Decision Making and the Brain (Elsevier, 2008), p. 95]. Here we report a similar study in which we recorded saccadic eye movements in a saccadic decision task in which monetary rewards and losses were associated with the final position of the eye movement. Saccades into a color-coded target region won points; saccades into a partially overlapping or abutting penalty region could yield a loss. The points won during the experiment were converted into a small monetary bonus at the end of the experiment. We compared participants' winnings to the score of an optimal observer maximizing expected gain that was calculated based on each participant's saccadic endpoint variability, similar to a recent model of optimal movement planning under risk [J. Opt. Soc. Am. A 20, 1419 (2003)]; [Spatial Vis. 16, 255 (2003)]. We used three different experimental paradigms with different interstimulus intervals (Gap, No Gap, and Overlap) to manipulate saccadic latencies and a fourth experiment (Memory) with a prolonged 500 ms delay period. Our results show that our subjects took the reward information, as specified by the different penalties, into account when making saccades and fixated onto or very close to the target region and less into the penalty region. However, the selected strategies differed significantly from optimal strategies maximizing expected gain in conditions when the magnitude of reward or penalty was changed. Furthermore, scores were notably affected by stimulus saliency. They were higher when the target region was filled and the penalty region outlined by a thin line, as compared to conditions in which the target was indicated by a less salient stimulus. Scores were particularly poor in trials with the shortest latencies (120-140 ms) mostly obtained in the Gap paradigm. At longer latencies scores improved considerably for latencies longer than 160 ms. This was in line with an improvement in accuracy for single targets up to 160 ms. Our results indicate that processing both of reward information and of stimulus saliency affect the programming of saccades, with a dominating contribution of stimulus saliency for eye movements with faster latencies. |
Franziska Schrammel; Sebastian Pannasch; Sven-Thomas Graupner; Andreas Mojzisch; Boris M. Velichkovsky Virtual friend or threat? The effects of facial expression and gaze interaction on psychophysiological responses and emotional experience Journal Article In: Psychophysiology, vol. 46, no. 5, pp. 922–931, 2009. @article{Schrammel2009,The present study aimed to investigate the impact of facial expression, gaze interaction, and gender on attention allocation, physiological arousal, facial muscle responses, and emotional experience in simulated social interactions. Participants viewed animated virtual characters varying in terms of gender, gaze interaction, and facial expression. We recorded facial EMG, fixation duration, pupil size, and subjective experience. Subject's rapid facial reactions (RFRs) differentiated more clearly between the character's happy and angry expression in the condition of mutual eye-to-eye contact. This finding provides evidence for the idea that RFRs are not simply motor responses, but part of an emotional reaction. Eye movement data showed that fixations were longer in response to both angry and neutral faces than to happy faces, thereby suggesting that attention is preferentially allocated to cues indicating potential threat during social interaction. |
Alexander C. Schütz; Doris I. Braun; Karl R. Gegenfurtner Chromatic contrast sensitivity during optokinetic nystagmus, visually enhanced vestibulo-ocular reflex, and smooth pursuit eye movements Journal Article In: Journal of Neurophysiology, vol. 101, no. 5, pp. 2317–2327, 2009. @article{Schuetz2009,Recently we showed that sensitivity for chromatic- and high-spatial frequency luminance stimuli is enhanced during smooth-pursuit eye movements (SPEMs). Here we investigated whether this enhancement is a general property of slow eye movements. Besides SPEM there are two other classes of eye movements that operate in a similar range of eye velocities: the optokinetic nystagmus (OKN) is a reflexive pattern of alternating fast and slow eye movements elicited by wide-field visual motion and the vestibulo-ocular reflex (VOR) stabilizes the gaze during head movements. In a natural environment all three classes of eye movements act synergistically to allow clear central vision during self- and object motion. To test whether the same improvement of chromatic sensitivity occurs during all of these eye movements, we measured human detection performance of chromatic and luminance line stimuli during OKN and contrast sensitivity during VOR and SPEM at comparable velocities. For comparison, performance in the same tasks was tested during fixation. During the slow phase of OKN we found a similar enhancement of chromatic detection rate like that during SPEM, whereas no enhancement was observable during VOR. This result indicates similarities between slow-phase OKN and SPEM, which are distinct from VOR. |
Alexander C. Schütz; Doris I. Braun; Karl R. Gegenfurtner Object recognition during foveating eye movements Journal Article In: Vision Research, vol. 49, no. 18, pp. 2241–2253, 2009. @article{Schuetz2009a,We studied how saccadic and smooth pursuit eye movements affect the recognition of briefly presented letters appearing within the eye movement target. First we compared the recognition performance during steady-state pursuit and during fixation. Single letters were presented for seven different durations ranging from 10 to 400 ms and four contrast levels ranging from 5% to 40%. For both types of eye movements the recognition rates increased with duration and contrast, but they were on average 11% lower during pursuit. In daily life humans use a combination of saccadic and smooth pursuit eye movements to foveate a peripheral moving object. To investigate this more natural situation, we presented a peripheral target that was either stationary or moving horizontally, above or below the fixation spot. Participants were asked to saccade to the target and to keep it foveated. The letters were presented at different times relative to the first target directed saccade. As would be expected from retinal masking and motion blur during saccades, the discrimination performance increased with increasing post-saccadic delay. If the target moved and the saccade was followed by pursuit, letter recognition performance was on average 16% lower than if the target was stationary and the saccade was followed by fixation. |
Alexander C. Schütz; Doris I. Braun; Karl R. Gegenfurtner; Alexander C. Schu Improved visual sensitivity during smooth pursuit eye movements: Temporal and spatial characteristics Journal Article In: Visual Neuroscience, vol. 26, no. 3, pp. 329–340, 2009. @article{Schuetz2009b,Recently, we showed that contrast sensitivity for color and high–spatial frequency luminance stimuli is enhanced during smooth pursuit eye movements (Schütz et al., 2008). In this study, we investigated the enhancement over a wide range of temporal and spatial frequencies. In Experiment 1, we measured the temporal impulse response function (TIRF) for colored stimuli. The TIRF for pursuit and fixation differed mostly with respect to the gain but not with respect to the natural temporal frequency. Hence, the sensitivity enhancement seems to be rather independent of the temporal frequency of the stimuli. In Experiment 2, we measured the spatial contrast sensitivity function for luminance-defined Gabor patches with spatial frequencies ranging from 0.2 to 7 cpd. We found a sensitivity improvement during pursuit for spatial frequencies above 2–3 cpd. Between 0.5 and 3 cpd, sensitivity was impaired by smooth pursuit eye movements, but no consistent difference was observed below 0.5 cpd. The results of both experiments are consistent with an increased contrast gain of the parvocellular retinogeniculate pathway. |
Naoyuki Sato; Yoko Yamaguchi A computational predictor of human episodic memory based on a theta phase precession network Journal Article In: PLoS ONE, vol. 4, no. 10, pp. e7536, 2009. @article{Sato2009,In the rodent hippocampus, a phase precession phenomena of place cell firing with the local field potential (LFP) theta is called "theta phase precession" and is considered to contribute to memory formation with spike time dependent plasticity (STDP). On the other hand, in the primate hippocampus, the existence of theta phase precession is unclear. Our computational studies have demonstrated that theta phase precession dynamics could contribute to primate-hippocampal dependent memory formation, such as object-place association memory. In this paper, we evaluate human theta phase precession by using a theory-experiment combined analysis. Human memory recall of object-place associations was analyzed by an individual hippocampal network simulated by theta phase precession dynamics of human eye movement and EEG data during memory encoding. It was found that the computational recall of the resultant network is significantly correlated with human memory recall performance, while other computational predictors without theta phase precession are not significantly correlated with subsequent memory recall. Moreover the correlation is larger than the correlation between human recall and traditional experimental predictors. These results indicate that theta phase precession dynamics are necessary for the better prediction of human recall performance with eye movement and EEG data. In this analysis, theta phase precession dynamics appear useful for the extraction of memory-dependent components from the spatio-temporal pattern of eye movement and EEG data as an associative network. Theta phase precession may be a common neural dynamic between rodents and humans for the formation of environmental memories. |
Joseph Schmidt; Gregory J. Zelinsky Search guidance is proportional to the categorical specificity of a target cue Journal Article In: Quarterly Journal of Experimental Psychology, vol. 62, no. 10, pp. 1904–1914, 2009. @article{Schmidt2009,Visual search studies typically assume the availability of precise target information to guide search, often a picture of the exact target. However, search targets in the real world are often defined categorically and with varying degrees of visual specificity. In five target preview conditions we manipulated the availability of target visual information in a search task for common real-world objects. Previews were: a picture of the target, an abstract textual description of the target, a precise textual description, an abstract + colour textual description, or a precise + colour textual description. Guidance generally increased as information was added to the target preview. We conclude that the information used for search guidance need not be limited to a picture of the target. Although generally less precise, to the extent that visual information can be extracted from a target label and loaded into working memory, this information too can be used to guide search. |
Tamara L. Watson; Bart Krekelberg The relationship between saccadic suppression and perceptual stability Journal Article In: Current Biology, vol. 19, no. 12, pp. 1040–1043, 2009. @article{Watson2009,Introspection makes it clear that we do not see the visual motion generated by our saccadic eye movements. We refer to the lack of awareness of the motion across the retina that is generated by a saccade as saccadic omission [1]: the visual stimulus generated by the saccade is omitted from our subjective awareness. In the laboratory, saccadic omission is often studied by investigating saccadic suppression, the reduction in visual sensitivity before and during a saccade (see Ross et al. [2] and Wurtz [3] for reviews). We investigated whether perceptual stability requires that a mechanism like saccadic suppression removes perisaccadic stimuli from visual processing to prevent their presumed harmful effect on perceptual stability [4, 5]. Our results show that a stimulus that undergoes saccadic omission can nevertheless generate a shape contrast illusion. This illusion can be generated when the inducer and test stimulus are separated in space and is therefore thought to be generated at a later stage of visual processing [6]. This shows that perceptual stability is attained without removing stimuli from processing and suggests a conceptually new view of perceptual stability in which perisaccadic stimuli are processed by the early visual system, but these signals are prevented from reaching awareness at a later stage of processing. |
Andrew E. Welchman; Julie M. Harris; Eli Brenner Extra-retinal signals support the estimation of 3D motion Journal Article In: Vision Research, vol. 49, no. 7, pp. 782–789, 2009. @article{Welchman2009,In natural settings, our eyes tend to track approaching objects. To estimate motion, the brain should thus take account of eye movements, perhaps using retinal cues (retinal slip of static objects) or extra-retinal signals (motor commands). Previous work suggests that extra-retinal ocular vergence signals do not support the perceptual judgments. Here, we re-evaluate this conclusion, studying motion judgments based on retinal slip and extra-retinal signals. We find that (1) each cue can be sufficient, and, (2) retinal and extra-retinal signals are combined, when estimating motion-in-depth. This challenges the accepted view that observers are essentially blind to eye vergence changes. |
Åsa Wengelin; Mark Torrance; Kenneth Holmqvist; Sol Simpson; David Galbraith; Victoria Johansson; Roger Johansson Combined eyetracking and keystroke-logging methods for studying cognitive processes in text production Journal Article In: Behavior Research Methods, vol. 41, no. 2, pp. 337–351, 2009. @article{Wengelin2009,Writers typically spend a certain proportion of time looking back over the text that they have written. This is likely to serve a number of different functions, which are currently poorly understood. In this article, we present two systems, ScriptLog+ TimeLine and EyeWrite, that adopt different and complementary approaches to exploring this activity by collecting and analyzing combined eye movement and keystroke data from writers composing extended texts. ScriptLog+ TimeLine is a system that is based on an existing keystroke-logging program and uses heuristic, pattern-matching methods to identify reading episodes within eye movement data. EyeWrite is an integrated editor and analysis system that permits identification of the words that the writer fixates and their location within the developing text. We demonstrate how the methods instantiated within these systems can be used to make sense of the large amount of data generated by eyetracking and keystroke logging in order to inform understanding of the cognitive processes that underlie written text production. |
Gregory L. West; Timothy N. Welsh; Jay Pratt Saccadic trajectories receive online correction: Evidence for a feedback-based system of oculomotor control Journal Article In: Journal of Motor Behavior, vol. 41, no. 2, pp. 117–126, 2009. @article{West2009,Although a considerable amount of research has investigated the planning and production of saccadic eye movements, it remains unclear whether (a) central planning processes prior to movement onset largely determine these eye movements or (b) they receive online correction during the actual trajectory. To investigate this issue, the authors measured the spatial position of the eye at specific kinematic markers during saccadic movements (i.e., peak acceleration, peak velocity, peak deceleration, saccade endpoint). In 2 experiments, the authors examined saccades ranging in amplitude from 4 to 20 degrees and computed the variability profiles (SD) of eye position at each kinematic marker and the proportion of explained variance (R2) between each kinematic marker and the saccade endpoint. In Experiment 1, the authors examined differences in the kinematic signature of saccadic online control between eye movements made in gap or overlap conditions. In Experiment 2, the authors examined the online control of saccades made from stored target information after delays of 500, 1,500, and 3,500 ms. Findings evince a robust and consistent feedback-based system of online oculomotor control during saccadic eye movements. |
Sébastien Tremblay; Jean Saint-Aubin Evidence of anticipatory eye movements in the spatial Hebb repetition effect: Insights for modeling sequence learning Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 35, no. 5, pp. 1256–1265, 2009. @article{Tremblay2009,In the present study, the authors offer a window onto the mechanisms that drive the Hebb repetition effect through the analysis of eye movement and recall performance. In a spatial serial recall task in which sequences of dots are to be remembered in order, when one particular series is repeated every 4 trials, memory performance markedly improves over repetitions. This is known as the Hebb repetition effect. Eye movement recorded during the presentation of the to-be-remembered (TBR) information revealed that for the repeated sequence, participants fixated the location of the next TBR location before the actual presentation of the dot. The extent to which a TBR location was anticipated increased over repetition and occurred only for post-initial positions of the repeated sequence. Eye movement-based rehearsal activity was related to recall performance but not to sequence learning. The findings provide further evidence of anticipatory behavior in sequence learning and place key constraints on modeling the Hebb repetition effect. |
Po-He Tseng; Ran Carmi; Ian G. M. Cameron; Douglas P. Munoz; Laurent Itti Quantifying center bias of observers in free viewing of dynamic natural scenes Journal Article In: Journal of Vision, vol. 9, no. 7, pp. 4–4, 2009. @article{Tseng2009,Human eye-tracking studies have shown that gaze fixations are biased toward the center of natural scene stimuli ("center bias"). This bias contaminates the evaluation of computational models of attention and oculomotor behavior. Here we recorded eye movements from 17 participants watching 40 MTV-style video clips (with abrupt scene changes every 2-4 s), to quantify the relative contributions of five causes of center bias: photographer bias, motor bias, viewing strategy, orbital reserve, and screen center. Photographer bias was evaluated by five naive human raters and correlated with eye movements. The frequently changing scenes in MTV-style videos allowed us to assess how motor bias and viewing strategy affected center bias across time. In an additional experiment with 5 participants, videos were displayed at different locations within a large screen to investigate the influences of orbital reserve and screen center. Our results demonstrate quantitatively for the first time that center bias is correlated strongly with photographer bias and is influenced by viewing strategy at scene onset, while orbital reserve, screen center, and motor bias contribute minimally. We discuss methods to account for these influences to better assess computational models of visual attention and gaze using natural scene stimuli. |
Naotsugu Tsuchiya; Farshad Moradi; Csilla Felsen; Madoka Yamazaki; Ralph Adolphs Intact rapid detection of fearful faces in the absence of the amygdala Journal Article In: Nature Neuroscience, vol. 12, no. 10, pp. 1224–1225, 2009. @article{Tsuchiya2009,The amygdala is thought to process fear-related stimuli rapidly and nonconsciously. We found that an individual with complete bilateral amygdala lesions, who cannot recognize fear from faces, nonetheless showed normal rapid detection and nonconscious processing of those same fearful faces. We conclude that the amygdala is not essential for early stages of fear processing but, instead, modulates recognition and social judgment. |
Ilse Tydgat; Jonathan Grainger Serial position effects in the identification of letters, digits, and symbols Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 35, no. 2, pp. 480–498, 2009. @article{Tydgat2009,In 6 experiments, the authors investigated the form of serial position functions for identification of letters, digits, and symbols presented in strings. The results replicated findings obtained with the target search paradigm, showing an interaction between the effects of serial position and type of stimulus, with symbols generating a distinct serial position function compared with letters and digits. When the task was 2-alternative forced choice, this interaction was driven almost exclusively by performance at the first position in the string, with letters and digits showing much higher levels of accuracy than symbols at this position. A final-position advantage was reinstated in Experiment 6 by placing the two alternative responses below the target string. The end-position (first and last positions) advantage for letters and digits compared with symbol stimuli was further confirmed with the bar-probe technique (postcued partial report) in Experiments 5 and 6. Overall, the results further support the existence of a specialized mechanism designed to optimize processing of strings of letters and digits by modifying the size and shape of retinotopic character detectors' receptive fields. |
Geoffrey Underwood; Tom Foulsham; Katherine Humphrey Saliency and scan patterns in the inspection of real-world scenes: Eye movements during encoding and recognition Journal Article In: Visual Cognition, vol. 17, no. 6-7, pp. 812–834, 2009. @article{Underwood2009,How do sequences of eye fixations match each other when viewing a picture during encoding and again during a recognition test, and to what extent are fixation sequences (scan patterns) determined by the low-level visual features of the picture rather than the domain knowledge of the viewer? The saliency map model of visual attention was tested in two experiments to ask whether the rank ordering of regions by their saliency values can be used to predict the sequence of fixations made when first looking at an image. Experiment 1 established that the sequence of fixations on first inspection during encoding was similar to that made when looking at the picture the second time, in the recognition test. Experiment 2 confirmed this similarity of fixation sequences at encoding and recognition, and also found a similarity between scan patterns made during the initial recognition test and during a second recognition test 1 week later. The fixation scan patterns were not similar to those predicted by the saliency map model in either experiment, however. These conclusions are qualified by interactions involving the match between the content of the image and the domain of interest of the viewers. How do sequences of eye fixations match each other when viewing a picture during encoding and again during a recognition test, and to what extent are fixation sequences (scan patterns) determined by the low-level visual features of the picture rather than the domain knowledge of the viewer? The saliency map model of visual attention was tested in two experiments to ask whether the rank ordering of regions by their saliency values can be used to predict the sequence of fixations made when first looking at an image. Experiment 1 established that the sequence of fixations on first inspection during encoding was similar to that made when looking at the picture the second time, in the recognition test. Experiment 2 confirmed this similarity of fixation sequences at encoding and recognition, and also found a similarity between scan patterns made during the initial recognition test and during a second recognition test 1 week later. The fixation scan patterns were not similar to those predicted by the saliency map model in either experiment, however. These conclusions are qualified by interactions involving the match between the content of the image and the domain of interest of the viewers. |
Seppo Vainio; Jukka Hyönä; Anneli Pajunen Lexical predictability exerts robust effects on fixation duration, but not on initial landing position during reading Journal Article In: Experimental Psychology, vol. 56, no. 1, pp. 66–74, 2009. @article{Vainio2009,An eye movement experiment was conducted to examine effects of local lexical predictability on fixation durations and fixation locations during sentence reading. In the high-predictability condition, a verb strongly constrained the lexical identity of the following word, while in the low-predictability condition the target word could not be predicted on the basis of the verb. The results showed that first fixation and gaze duration on the target noun were reliably shorter in the high-predictability than in the low-predictability condition. However, initial fixation location was not affected by lexical predictability. As regards eye guidance in reading, the present study indicates that local lexical predictability influences when decisions but not where the initial fixation lands in a word. |
Melissa L. -H. Võ; John M. Henderson Does gravity matter? Effects of semantic and syntactic inconsistencies on the allocation of attention during scene perception Journal Article In: Journal of Vision, vol. 9, no. 3, pp. 24–24, 2009. @article{Vo2009,It has been shown that attention and eye movements during scene perception are preferentially allocated to semantically inconsistent objects compared to their consistent controls. However, there has been a dispute over how early during scene viewing such inconsistencies are detected. In the study presented here, we introduced syntactic object–scene inconsistencies (i.e., floating objects) in addition to semantic inconsistencies to investigate the degree to which they attract attention during scene viewing. In Experiment 1 participants viewed scenes in preparation for a subsequent memory task, while in Experiment 2 participants were instructed to search for target objects. In neither experiment were we able to find evidence for extrafoveal detection of either type of inconsistency. However, upon fixation both semantically and syntactically inconsistent objects led to increased object processing as seen in elevated gaze durations and number of fixations. Interestingly, the semantic inconsistency effect was diminished for floating objects, which suggests an interaction of semantic and syntactic scene processing. This study is the first to provide evidence for the influence of syntactic in addition to semantic object–scene inconsistencies on eye movement behavior during real-world scene viewing. |
Michael Wagner; Walter H. Ehrenstein; Thomas V. Papathomas Vergence in reverspective: Percept-driven versus data-driven eye movement control Journal Article In: Neuroscience Letters, vol. 449, no. 2, pp. 142–146, 2009. @article{Wagner2009,'Reverspectives' (by artist Patrick Hughes) consist of truncated pyramids with their small faces closer to the viewer, allowing realistic scenes to be painted on them. Because their pictorial perspective reverses the physical depth arrangement, reverspectives provide a bistable paradigm of two radically different, competing depth percepts, even when viewed binocularly: points that are physically further are perceived to be closer and vice versa. The key question addressed here is whether vergence is governed by the physical and/or the perceived depth of fixated targets. Vergence eye movements were recorded using the EyeLink II system under conditions optimized to obtain both the veridical and illusory depth percepts of a reverspective. Six gaze locations were signaled by LEDs placed at strategically selected depths on the stimulus surface. We obtained strong evidence that stable vergence fixations were governed by the percept: for the same LED position, eyes converged under veridical depth percepts and diverged under illusory percepts, thus rendering pictorial cues to be as effective as physical cues in vergence control. These results, obtained with stable fixations, do not disagree with earlier studies that found rapid fixational eye movements to be governed by physical depth cues. Together, these results allow us to speculate on the existence of at least two eye movement systems: an automatic, data-driven system for rapid successions of fixations; and a deliberate schema-driven vergence system that accounts for stable fixations based on the perceptual state of the observer. |
Robin Walker; Puncharat Techawachirakul; Patrick Haggard Frontal eye field stimulation modulates the balance of salience between target and distractors Journal Article In: Brain Research, vol. 1270, pp. 54–63, 2009. @article{Walker2009,Natural scenes generally include several possible objects that can be the target for a shift of gaze and attention. The oculomotor system may select a single target by boosting neural activation representing the target, and also by inhibiting neural activity associated with competing alternatives (distractors). We examine the role of the frontal eye field (FEF) in these processes through the effects of single-pulse transcranial magnetic stimulation (TMS) on the distractor-related modulation of saccade trajectories. Participants made voluntary saccades to peripheral locations specified by a central arrow-cue. On some trials, visual distractors appeared remote from the target location. The competing distractor produced a deviation of saccade trajectory, away from the distractor location. Single-pulse TMS stimulation of the right frontal eye field increased this distractor-related deviation compared that observed when stimulation was applied to a control site (vertex). The increase in distractor-related deviation of trajectory, following FEF stimulation, was observed for saccades made in both the left and right visual fields and could not be attributed to an effect of TMS on saccade latency. The enhanced distractor-related deviation following FEF stimulation could reflect increased inhibition of the competing distractor, or reduced salience of the endogenous saccade goal. The results are interpreted in light of neurophysiological evidence that the human FEF is involved in the dynamic interaction between competing stimuli for the selection of a candidate target. |
Matteo Valsecchi; Massimo Turatto Microsaccadic responses in a bimodal oddball task Journal Article In: Psychological Research, vol. 73, no. 1, pp. 23–33, 2009. @article{Valsecchi2009,In a visual oddball task the presentation of rare targets induces a prolonged microsaccadic inhibition as compared to standards. Here, we replicated this effect also in the auditory modality. In addition, although auditory standards induced a more limited modulation of microsaccadic frequency as compared to visual standards, auditory oddballs induced a prolonged microsaccadic inhibition. With bimodal standard stimuli the microsaccadic response was determined by the attended modality, resembling that produced by attended unimodal stimuli. The present findings support the idea that the microsaccadic response to oddball and standard stimuli is partly driven by cognitive mechanisms common to both the visual and the auditory modality, and that microsaccades can be used as an implicit behavioral measure of ongoing cognitive processes. |
Eva Van Assche; Wouter Duyck; Robert J. Hartsuiker; Kevin Diependaele Does bilingualism change cognate effects in a sentence context Journal Article In: Psychological Science, vol. 20, no. 8, pp. 923–927, 2009. @article{VanAssche2009,Becoming a bilingual can change a person's cognitive functioning and language processing in a number of ways. This study focused on how knowledge of a second language influences how people read sentences written in their native language. We used the cognate-facilitation effect as a marker of cross-lingual activations in both languages. Cognates (e.g., Dutch-English schip [ship]) and controls were presented in a sentence context, and eye movements were monitored. Results showed faster reading times for cognates than for controls. Thus, this study shows that one of people's most automated skills, reading in one's native language, is changed by the knowledge of a second language. |
Menno Schoot; Annemieke H. Bakker Arkema; Tako M. Horsley; Ernest C. D. M. Lieshout In: Contemporary Educational Psychology, vol. 34, no. 1, pp. 58–66, 2009. @article{Schoot2009,This study examined the effects of consistency (relational term consistent vs. inconsistent with required arithmetic operation) and markedness (relational term unmarked ['more than'] vs. marked ['less than']) on word problem solving in 10-12 years old children differing in problem-solving skill. The results showed that for unmarked word problems, less successful problem solvers showed an effect of consistency on regressive eye movements (longer and more regressions to solution-relevant problem information for inconsistent than consistent word problems) but not on error rate. For marked word problems, they showed the opposite pattern (effects of consistency on error rate, not on regressive eye movements). The conclusion was drawn that, like more successful problem solvers, less successful problem solvers can appeal to a problem-model strategy, but that they do so only when the relational term is unmarked. The results were discussed mainly with respect to the linguistic-semantic aspects of word problem solving. |
Menno Schoot; Alain L. Vasbinder; Tako M. Horsley; Albert Reijntjes; Ernest C. D. M. Lieshout Lexical ambiguity resolution in good and poor comprehenders: An eye fixation and self-paced reading study in primary school children Journal Article In: Journal of Educational Psychology, vol. 101, no. 1, pp. 21–36, 2009. @article{Schoot2009a,To investigate the use of context and monitoring of comprehension in lexical ambiguity resolution in children, the authors asked 10- to 12-year-old good and poor comprehenders to read sentences consisting of 2 clauses, 1 containing the ambiguous word and the other the disambiguating information. The order of the clauses was reversed so that disambiguating information either preceded or followed the ambiguous word. Context use and comprehension monitoring were examined by measuring eye fixations (Experiment 1) and self-paced reading times (Experiment 2) on the ambiguous word and disambiguating region. The results of Experiment 1 and 2 showed that poor comprehenders made use of prior context to facilitate lexical ambiguity resolution as effectively as good comprehenders but that they monitored their comprehension less effectively than good comprehenders. Good comprehenders corrected an initial interpretation error on an ambiguous word and restored comprehension once they encountered the disambiguating region. Poor comprehenders failed to deal with this type of comprehension failure. |
Stefan Van der Stigchel; Manon Mulckhuyse; Jan Theeuwes Eye cannot see it: The interference of subliminal distractors on saccade metrics Journal Article In: Vision Research, vol. 49, no. 16, pp. 2104–2109, 2009. @article{VanderStigchel2009,The present study investigated whether subliminal (unconsciously perceived) visual information influences eye movement metrics, like saccade trajectories and endpoints. Participants made eye movements upwards and downwards while a subliminal distractor was presented in the periphery. Results showed that the subliminal distractor interfered with the execution of an eye movement, although the effects were smaller compared to a control experiment in which the distractor was presented supraliminal. Because saccade metrics are mediated by low level brain areas, this indicates that subliminal visual information evokes competition at a very low level in the oculomotor system. |
Helene M. Ettinger-Veenstra; W. Huijbers; Tjerk P. Gutteling; M. Vink; J. Leon Kenemans; Sebastiaan F. W. Neggers In: Journal of Neurophysiology, vol. 102, no. 6, pp. 3469–3480, 2009. @article{EttingerVeenstra2009,It is well known that parts of a visual scene are prioritized for visual processing, depending on the current situation. How the CNS moves this focus of attention across the visual image is largely unknown, although there is substantial evidence that preparation of an action is a key factor. Our results support the view that direct corticocortical feedback connections from frontal oculomotor areas to the visual cortex are responsible for the coupling between eye movements and shifts of visuospatial attention. Functional magnetic resonance imaging (fMRI)-guided transcranial magnetic stimulation (TMS) was applied to the frontal eye fields (FEFs) and intraparietal sulcus (IPS). A single pulse was delivered 60, 30, or 0 ms before a discrimination target was presented at, or next to, the target of a saccade in preparation. Results showed that the known enhancement of discrimination performance specific to locations to which eye movements are being prepared was enhanced by early TMS on the FEF contralateral to eye movement direction, whereas TMS on the IPS resulted in a general performance increase. The current findings indicate that the FEF affects selective visual processing within the visual cortex itself through direct feedback projections. |
Kate Janse Van Rensburg; Adrian Taylor; Timothy L. Hodgson The effects of acute exercise on attentional bias towards smoking-related stimuli during temporary abstinence from smoking Journal Article In: Addiction, vol. 104, no. 11, pp. 1910–1917, 2009. @article{VanRensburg2009,RATIONALE: Attentional bias towards smoking-related cues is increased during abstinence and can predict relapse after quitting. Exercise has been found to reduce cigarette cravings and desire to smoke during temporary abstinence and attenuate increased cravings in response to smoking cues. OBJECTIVE: To assess the acute effects of exercise on attentional bias to smoking-related cues during temporary abstinence from smoking. METHOD: In a randomized cross-over design, on separate days regular smokers (n = 20) undertook 15 minutes of exercise (moderate intensity stationary cycling) or passive seating following 15 hours of nicotine abstinence. Attentional bias was measured at baseline and post-treatment. The percentage of dwell time and direction of initial fixation was assessed during the passive viewing of a series of paired smoking and neutral images using an Eyelink II eye-tracking system. Self-reported desire to smoke was recorded at baseline, mid- and post-treatment and post-eye-tracking task. RESULTS: There was a significant condition x time interaction for desire to smoke, F((1,18)) = 10.67 |
Verena Thaler; Karolina Urton; Angela Heine; Stefan Hawelka; Verena Engl; Arthur M. Jacobs Different behavioral and eye movement patterns of dyslexic readers with and without attentional deficits during single word reading Journal Article In: Neuropsychologia, vol. 47, no. 12, pp. 2436–2445, 2009. @article{Thaler2009,Comorbidity of learning disabilities is a very common phenomenon which is intensively studied in genetics, neuropsychology, prevalence studies and causal deficit research. In studies on the behavioral manifestation of learning disabilities, however, comorbidity is often neglected. In the present study, we systematically examined the reading behavior of German-speaking children with dyslexia, of children with attentional problems, of children with comorbid dyslexia and attentional problems and of normally developing children by measuring their reading accuracy, naming latencies and eye movement patterns during single word reading. We manipulated word difficulty by contrasting (1) short vs. long words with (2) either low or high sublexical complexity (indexed by consonant cluster density). Children with dyslexia only (DYS) showed the expected reading fluency impairment of poor readers in regular orthographies but no accuracy problem. In contrast, comorbid children (DYS + AD) had significantly higher error rates than all other groups, but less of a problem with reading fluency than DYS. Concurrently recorded eye movement measures revealed that DYS made the highest number of fixations, but exhibited shorter mean single fixations than DYS + AD. Word length had the strongest effect on dyslexic children, whereas consonant cluster density affected all groups equally. Theoretical implications of these behavioral and eye movement patterns are discussed and the necessity for controlling for comorbid attentional deficits in children with reading deficits is highlighted. |
Jan Theeuwes; Artem V. Belopolsky No functional role of attention-based rehearsal in maintenance of spatial working memory representations Journal Article In: Acta Psychologica, vol. 132, no. 2, pp. 124–135, 2009. @article{Theeuwes2009,The present study systematically examined the role of attention in maintenance of spatial representations in working memory as proposed by the attention-based rehearsal hypothesis [Awh, E., Jonides, J., & Reuter-Lorenz, P. A. (1998). Rehearsal in spatial working memory. Journal of Experimental Psychology--Human Perception and Performance, 24(3), 780-790]. Three main issues were examined. First, Experiments 1-3 demonstrated that inhibition and not facilitation of visual processing is often observed at the memorized location during the retention interval. This inhibition was caused by keeping a location in memory and not by the exogenous nature of the memory cue. Second, Experiment 4 showed that inhibition of the memorized location does not lead to any significant impairment in memory accuracy. Finally, Experiment 5 connected current results to the previous findings and demonstrated facilitation of processing at the memorized location. Importantly, facilitation of processing did not lead to more accurate memory performance. The present results challenge the functional role of attention in maintenance of spatial working memory representations. |
Jan Theeuwes; Stefan Van der Stigchel Saccade trajectory deviations and inhibition-of-return: Measuring the amount of attentional processing Journal Article In: Vision Research, vol. 49, no. 10, pp. 1307–1315, 2009. @article{Theeuwes2009a,This study used a classic exogenous cueing task in which an abrupt onset cue indicated the target location at chance level. When there was a delay between the cue and the target, observers responded slower and less accurate to the target presented at cued than at uncued locations, signifying the occurrence of inhibition-of-return (IOR). On some trials, instead of a manual response, participants had to move their eyes to a location in space. Our findings show no saccade deviation away from the location that was inhibited due to IOR unless participants had to process the target letter presented at the inhibited location. Our findings are consistent with the notion that inhibition resulting in IOR does not occur at the saccade map level but IOR seems to reduce the input of signals going into the saccade map. We show that the strength of saccade deviation is an important measure which can reveal the amount of attentional processing taking place at any particular location in time. |
Dhushan Thevarajah; Areh Mikulić; Michael C. Dorris Role of the superior colliculus in choosing mixed-strategy saccades Journal Article In: Journal of Neuroscience, vol. 29, no. 7, pp. 1998–2008, 2009. @article{Thevarajah2009,Game theory outlines optimal response strategies during mixed-strategy competitions. The neural processes involved in choosing individual strategic actions, however, remain poorly understood. Here, we tested whether the superior colliculus (SC), a brain region critical for generating sensory-guided saccades, is also involved in choosing saccades under strategic conditions. Monkeys were free to choose either of two saccade targets as they competed against a computer opponent during the mixed-strategy game "matching pennies." The accuracy with which presaccadic SC activity predicted upcoming choice gradually increased in the time leading up to the saccade. Probing the SC with suprathreshold stimulation demonstrated that these evolving signals were functionally involved in preparing strategic saccades. Finally, subthreshold stimulation of the SC increased the likelihood that contralateral saccades were selected. Together, our results suggest that motor regions of the brain play an active role in choosing strategic actions rather than passively executing those prespecified by upstream executive regions. |
Laura E. Thomas; Alejandro Lleras Covert shifts of attention function as an implicit aid to insight Journal Article In: Cognition, vol. 111, no. 2, pp. 168–174, 2009. @article{Thomas2009,Previous research shows that directed actions can unconsciously influence higher-order cognitive processing, helping learners to retain knowledge and guiding problem solvers to useful insights (e.g. Cook, S. W., Mitchell, Z., & Goldin-Meadow, S. (2008). Gesturing makes learning last. Cognition, 106, 1047-1058; Thomas, L. E., & Lleras, A. (2007). Moving eyes and moving thought: on the spatial compatibility between eye movements and cognition. Psychonomic Bulletin and Review, 14, 663-668). We examined whether overt physical movement is necessary for these embodied effects on cognition, or whether covert shifts of attention are sufficient to influence cognition. We asked participants to try to solve Duncker's radiation problem while occasionally directing them, via an unrelated digit-tracking task, to shift their attention (while keeping their eyes fixed) in a pattern related to the problem's solution, to move their eyes in this pattern, or to keep their eyes and their attention fixed in the center of the display. Although they reported being unaware of any relationship between the digit-tracking task and the radiation problem, participants in both the eye-movement and attention-shift groups were more likely to solve the problem than were participants who maintained fixation. Our results show that by shifting attention in a pattern compatible with a problem's solution, we can aid participants' insight even in the absence of overt physical movements. |
Chin-An Wang; Albrecht W. Inhoff; Ralph Radach Is attention confined to one word at a time? The spatial distribution of parafoveal preview benefits during reading Journal Article In: Attention, Perception, and Psychophysics, vol. 71, no. 7, pp. 1487–1494, 2009. @article{Wang2009a,Eye movements were recorded while participants read declarative sentences. Each sentence contained a criti- cal three-word sequence with a three-letter target word (n), a spatially adjacent post-target word (n+1), and a subsequent nonadjacent post-target word (n+2). The parafoveal previews of words n and n+2 were manipulated so that they were either fully visible or masked until they were fixated. The results revealed longer word n and word n+1 viewing durations when word n had been masked in the parafovea, and this occurred irrespective of whether the target was skipped or fixated. Furthermore, masking of word n diminished the usefulness of the preview of word n+2. These results indicate that the effect of a parafoveally available target preview was not strictly localized. Instead, it influenced target viewing and the viewing of the two subsequent words in the text. These results are difficult to reconcile with the assumption that attention is confined to one word at a time until that word is recognized and that attention is then shifted from the recognized word to the next. |
Chin-An Wang; Jie-Li Tsai; Albrecht W. Inhoff; Ovid J. L. Tzeng Acquisition of linguistic information to the left of fixation during the reading of Chinese text Journal Article In: Language and Cognitive Processes, vol. 24, no. 7-8, pp. 1097–1123, 2009. @article{Wang2009b,The linguistic properties of the first (critical) character of a two-character Chinese word were manipulated when the eyes moved to the right of the critical character during reading to determine whether character processing is strictly unidirectional. In Experiment 1, the critical character was replaced with a congruent or incongruent character or left unchanged. Critical character changes did not influence the fixation duration, but incongruent changes led to more regressions than congruent changes. In Experiment 2, the critical character was replaced with either a homophonic or a non-homophonic character when it was to the left of fixation. The fixation following the change was now longer when the replaced character and the critical character were homophones than when they were phonologically dissimilar. These results indicate that readers obtain phonological and semantic information to the left of a fixated character and that the recognition of consecutive Chinese characters is not strictly unidirectional. |
Hsueh-Cheng Wang; Alex D. Hwang; Marc Pomplun Object frequency and predictability effects on eye fixation durations in real-world scene viewing Journal Article In: Journal of Eye Movement Research, vol. 3, no. 3, pp. 1–10, 2009. @article{Wang2009c,During text reading, the durations of eye fixations decrease with greater frequency and predictability of the currently fixated word (Rayner, 1998; 2009). However, it has not been tested whether those results also apply to scene viewing. We computed object frequency and predictability from both linguistic and visual scene analysis (LabelMe, Russell et al., 2008), and Latent Semantic Analysis (Landauer et al., 1998) was applied to estimate predictability. In a scene-viewing experiment, we found that, for small objects, linguistics-based frequency, but not scene-based frequency, had effects on first fixation duration, gaze duration, and total time. Both linguistic and scene-based predictability affected total time. Similar to reading, fixation duration decreased with higher frequency and predictability. For large objects, we found the direction of effects to be the inverse of those found in reading studies. These results suggest that the recognition of small objects in scene viewing shares some characteristics with the recognition of words in reading. |
Z. I. Wang; Louis F. Dell'Osso Factors influencing pursuit ability in infantile nystagmus syndrome: Target timing and foveation capability. Journal Article In: Vision Research, vol. 49, no. 2, pp. 182–189, 2009. @article{Wang2009,We wished to determine the influential factors for Infantile Nystagmus Syndrome (INS) subjects' ability to acquire and pursue moving targets using predictions from the behavioral Ocular Motor System (OMS) model and data from INS subjects. Ocular motor simulations using a behavioral OMS model were performed in MATLAB Simulink. Eye-movement recordings were performed using a high-speed digital video system. We studied five INS subjects who pursued a 10°/s ramp target to both left and right. We measured their target-acquisition times based on position criteria. The following parameters were studied: Lt (measured from the target-ramp initiation to the first on-target foveation period), target pursuit direction, and foveation-period pursuit gain. Analyses and simulations were performed in MATLAB environment using OMLAB software (OMtools, download from http://www.omlab.org). Ramp-target timing influenced target-acquisition time; the closer to the intrinsic saccades in the waveform the ramp stimuli started, the longer was Lt. However, arriving at the target position may not guarantee its foveation. Foveation-period pursuit gains vs. target or slow-phase direction had an idiosyncratic relationship for each subject. Adjustments to the model's Fixation subsystem reproduced the idiosyncratic foveation-period pursuit gains; the gain of the Smooth Pursuit subsystem was maintained at its normal value. The model output predicted a steady-state error when target initiation occurred during intrinsic saccades, consistent with human data. We conclude that INS subjects acquire ramp targets with longer latency for target initiations during or near the intrinsic saccades, consistent with the findings in our step-stimuli timing study. This effect might be due to the interaction between the saccadic and pursuit systems. The combined effects of target timing and Fixation-subsystem gain determined how fast and how well the INS subjects pursued ramp stimuli during their foveations periods (i.e., their foveation-period pursuit gain). The OMS model again demonstrated its behavioral characteristics and prediction capabilities (e.g., steady-state error) and revealed an important interaction between the Fixation and Smooth Pursuit subsystems. |
Tessa Warren; Sarah J. White; Erik D. Reichle Investigating the causes of wrap-up effects: Evidence from eye movements and E-Z Reader Journal Article In: Cognition, vol. 111, no. 1, pp. 132–137, 2009. @article{Warren2009,Wrap-up effects in reading have traditionally been thought to reflect increased processing associated with intra- and inter-clause integration (Just, M. A. & Carpenter, P. A. (1980). A theory of reading: From eye fixations to comprehension. Psychological Review, 87(4), 329-354; Rayner, K., Kambe, G., & Duffy, S. A. (2000). The effect of clause wrap-up on eye movements during reading. The Quarterly Journal of Experimental Psychology, 53A(4), 1061-1080; cf. Hirotani, M., Frazier, L., & Rayner, K. (2006). Punctuation and intonation effects on clause and sentence wrap-up: Evidence from eye movements. Journal of Memory and Language, 54, 425-443). We report an eye-tracking experiment with a strong manipulation of integrative complexity at a critical word that was either sentence-final, ended a comma-marked clause, or was not comma-marked. Although both complexity and punctuation had reliable effects, they did not interact in any eye-movement measure. These results as well as simulations using the E-Z Reader model of eye-movement control (Reichle, E. D., Warren, T., & McConnell, K. (2009). Using E-Z Reader to model the effects of higher-level language processing on eye movements during reading. Psychonomic Bulletin & Review, 16(1), 1-20) suggest that traditional accounts of clause wrap-up are incomplete. |
Karli K. Watson; Jason H. Ghodasra; Michael L. Platt Serotonin transporter genotype modulates social reward and punishment in rhesus macaques Journal Article In: PLoS ONE, vol. 4, no. 1, pp. e4156, 2009. @article{Watson2009a,BACKGROUND: Serotonin signaling influences social behavior in both human and nonhuman primates. In humans, variation upstream of the promoter region of the serotonin transporter gene (5-HTTLPR) has recently been shown to influence both behavioral measures of social anxiety and amygdala response to social threats. Here we show that length polymorphisms in 5-HTTLPR predict social reward and punishment in rhesus macaques, a species in which 5-HTTLPR variation is analogous to that of humans. METHODOLOGY/PRINCIPAL FINDINGS: In contrast to monkeys with two copies of the long allele (L/L), monkeys with one copy of the short allele of this gene (S/L) spent less time gazing at face than non-face images, less time looking in the eye region of faces, and had larger pupil diameters when gazing at photos of a high versus low status male macaques. Moreover, in a novel primed gambling task, presentation of photos of high status male macaques promoted risk-aversion in S/L monkeys but promoted risk-seeking in L/L monkeys. Finally, as measured by a "pay-per-view" task, S/L monkeys required juice payment to view photos of high status males, whereas L/L monkeys sacrificed fluid to see the same photos. CONCLUSIONS/SIGNIFICANCE: These data indicate that genetic variation in serotonin function contributes to social reward and punishment in rhesus macaques, and thus shapes social behavior in humans and rhesus macaques alike. |
Joris Vangeneugden; Frank E. Pollick; Rufin Vogels Functional differentiation of macaque visual temporal cortical neurons using a parametric action space Journal Article In: Cerebral Cortex, vol. 19, no. 3, pp. 593–611, 2009. @article{Vangeneugden2009,Neurons in the rostral superior temporal sulcus (STS) are responsive to displays of body movements. We employed a parametric action space to determine how similarities among actions are represented by visual temporal neurons and how form and motion information contributes to their responses. The stimulus space consisted of a stick-plus-point-light figure performing arm actions and their blends. Multidimensional scaling showed that the responses of temporal neurons represented the ordinal similarity between these actions. Further tests distinguished neurons responding equally strongly to static presentations and to actions ("snapshot" neurons), from those responding much less strongly to static presentations, but responding well when motion was present ("motion" neurons). The "motion" neurons were predominantly found in the upper bank/fundus of the STS, and "snapshot" neurons in the lower bank of the STS and inferior temporal convexity. Most "motion" neurons showed strong response modulation during the course of an action, thus responding to action kinematics. "Motion" neurons displayed a greater average selectivity for these simple arm actions than did "snapshot" neurons. We suggest that the "motion" neurons code for visual kinematics, whereas the "snapshot" neurons code for form/posture, and that both can contribute to action recognition, in agreement with computation models of action recognition. |
Rolf Verleger; Andreas Sprenger; Sina Gebauer; Michaela Fritzmannova; Monique Friedrich; Stefanie Kraft; Piotr Jaśkowski; Piotr Jas On why left events are the right ones: Neural mechanisms underlying the left-hemifield advantage in rapid serial visual presentation Journal Article In: Journal of Cognitive Neuroscience, vol. 21, no. 3, pp. 474–488, 2009. @article{Verleger2009,When simultaneous series of stimuli are rapidly presented left and right, containing two target stimuli T1 and T2, T2 is much better identified when presented in the left than in the right hemifield. Here, this effect was replicated, even when shifts of gaze were controlled, and was only partially compensated when T1 side provided the cue where to expect T2. Electrophysiological measurement revealed earlier latencies of T1- and T2-evoked N2(pc) peaks at the right than at the left visual cortex, and larger right-hemisphere T2-evoked N2(pc) amplitudes when T2 closely followed T1. These findings suggest that the right hemisphere was better able to single out the targets in time. Further, sustained contralateral slow shifts remained active after T1 for longer time at the right than at the left visual cortex, and developed more consistently at the right visual cortex when expecting T2 on the contralateral side. These findings might reflect better capacity of right-hemisphere visual working memory. These findings about the neurophysiological underpinnings of the large right-hemisphere advantage in this complex visual task might help elucidating the mechanisms responsible for the severe disturbance of hemineglect following damage to the right hemisphere. |
Marine Vernet Binocular motor coordination during saccades and fixations while reading: A magnitude and time analysis Journal Article In: Journal of Vision, vol. 9, no. 2009, pp. 1–13, 2009. @article{Vernet2009,Reading involves saccades and fixations. Misalignment of the eyes should be small enough to allow sensory fusion. Recent studies reported disparity of the eyes during fixations. This study examines disconjugacy, i.e. change in disparity over time, both during saccades and fixations. Text reading saccades and saccades to single targets of similar sizes (2.5-) are compared. Young subjects were screened to avoid problems of binocular vision and oculomotor vergence. The results show high quality of motor binocular coordination in both tasks: the amplitude difference between the saccade of the eyes was approximately 0.16-; during the fixation period, the drift difference was only 0.13-. The disconjugate drift occurred mainly during the first 48 ms of fixation, was equally distributed to the eyes and was often reducing the saccade disconjugacy. Quality of coordination regardless of the task is indicative of robust physiological mechanisms. We suggest the existence of active binocular control mechanisms in which vergence signals may have a central role. Even computation of saccades may be based on continuous interaction between saccade and vergence. |
Marine Vernet; Qing Yang; Marie Gruselle; Mareike Trams; Zoï Kapoula Switching between gap and overlap pro-saccades: Cost or benefit? Journal Article In: Experimental Brain Research, vol. 197, no. 1, pp. 49–58, 2009. @article{Vernet2009a,Triggering of saccades depends on the task: in the gap task, fixation point switches off and target appears after a gap period; in the overlap task, target appears while fixation point is still on. Saccade latencies are shorter in the gap task, due to fixation disengagement and advanced movement preparation during the gap. The two modes of initiation are also hypothesized to be subtended by different cortical-subcortical circuits. This study tested whether interleaving the two tasks modifies latencies, due to switching between different modes of triggering. Two groups of healthy participants (21-29 vs. 39-55 years) made horizontal and vertical saccades in gap, overlap, and mixed tasks; saccades were recorded with the Eyelink. Both groups showed shorter latencies in the gap task, i.e. a robust gap effect and systematic differences between directions. For young adults, interleaving tasks made the latencies shorter or longer depending on direction, while for middle-age adults, latencies became longer for all directions. Our observations can be explained in the context of models such as that of Brown et al. (Neural Netw 17:471-510, 2004), which proposed that different combinations of frontal eye field (FEF) layers, interacting with cortico-subcortical areas, control saccade triggering in gap and overlap trials. Moreover, we suggest that in early adulthood, the FEF is functioning optimally; frequent changes of activity in the FEF can be beneficial, leading to shorter latencies, at least for some directions. However, for middle-age adults, frequent changes of activity of a less optimally functioning FEF can be time consuming. Studying the alternation of gap and overlap tasks provides a fine tool to explore development, aging and disease. |
Eric D. Vidoni; Jason S. McCarley; Jodi D. Edwards; Lara A. Boyd Manual and oculomotor performance develop contemporaneously but independently during continuous tracking Journal Article In: Experimental Brain Research, vol. 195, no. 4, pp. 611–620, 2009. @article{Vidoni2009,The coordination of the oculomotor and manual effector systems is an important component of daily motor behavior. Previous work has primarily examined oculomotor/manual coordination in discrete targeting tasks. Here we extend this work to learning a tracking task that requires continuous response and movement update. Over two sessions, participants practiced controlling a computer mouse with movements of their arm to follow a target moving in a repeated sequence. Eye movements were also recorded. In a retention test, participants demonstrated sequence-specific learning with both effector systems, but differences between effectors also were apparent. Time series analysis and multiple linear regression were employed to probe spatial and temporal contributions to overall tracking accuracy within each effector system. Sequence-specific oculomotor learning occurred only in the spatial domain. By contrast, sequence-specific learning at the arm was evident only in the temporal domain. There was minimal interdependence in error rates for the two effector systems, underscoring their independence during tracking. These findings suggest that the oculomotor and manual systems learn contemporaneously, but performance improvements manifest differently and rely on different elements of motor execution. The results may in part be a function of what the motor learning system values for each effector as a function of its effector's inertial properties. |
2008 |
S. M. EMRICH; J. D. N. RUPPEL; N. AL-AIDROOS; J. PRATT; S. FERBER Out with the old: Inhibition of old items in a preview search is limited Journal Article In: Perception and Psychophysics, vol. 70, no. 8, pp. 1552–1557, 2008. @article{EMRICH2008,If some of the distractors in a visual search task are previewed prior to the presentation of the remaining distractors and the target, search time is reduced relative to when all of the items are displayed simultaneously. Here, we tested whether the ability to preferentially search new items during such a preview search is limited. We confirmed previous studies: The proportion of fixations on old items was significantly less than chance. However, the probability of fixating old locations was negatively affected by increasing the number of previewed distractors, suggesting that inhibition is limited to a small number of old items. Furthermore, the ability to inhibit old locations was limited to the first four fixations, indicating that by the fifth fixation, the resources required to sustain inhibition had been depleted. Together, these findings suggest that inhibition of old items in a preview search is a top-down mediated process dependent on capacity-limited cognitive resources. |
Yasuhiro Seya; Hidetoshi Nakayasu; Patrick Patterson Visual search of trained and untrained drivers in a driving simulator Journal Article In: Japanese Psychological Research, vol. 50, no. 4, pp. 242–252, 2008. @article{Seya2008,To investigate the effects of driving experience on visual search during driving, we measured eye movements during driving tasks using a driving simulator. We evaluated trained and untrained drivers for selected driving road section types (for example, intersections and straight roads). Participants in the trained group had received driving training by the simulator before the experiment, while the others had no driving training by it. In the experiment, the participants were instructed to drive safely in the simulator. The results of scan paths showed that eye positions were less variable in the trained group than in the untrained group. Total eye-movement distances were shorter, and fixation durations were longer in the trained group than in the untrained group. These results suggest that trained drivers may perceive relevant information efficiently with few eye movements by using their anticipation skills and useful field of view, which may have been developed through their driving training in the simulator. |
R. GODIJN; A. F. KRAMER The effect of attentional demands on the antisaccade cost Journal Article In: Perception and Psychophysics, vol. 70, no. 5, pp. 795–806, 2008. @article{GODIJN2008,In the present study, we examined the effect of attentional demands on the antisaccade cost (the latency difference between antisaccades and prosaccades). Participants performed a visual search for a target digit and were required to execute a saccade toward (prosaccade) or away from (antisaccade) the target. The results of Experiment 1 revealed that the antisaccade cost was greater when the target was premasked (i.e., presented through the removal of line segments) than when it appeared as an onset. Furthermore, in premasked target conditions, the antisaccade cost was increased by the presentation of onset distractors. The results of Experiment 2 revealed that the antisaccade cost was greater in a difficult search task (a numeral 2 among 5s) than in an easy one (a 2 among 7s). The findings provide evidence that attentional demands increase the antisaccade cost. We propose that the attentional demands of the search task interfere with the attentional control required to select the antisaccade goal. |
Jay Pratt; Bas Neggers Inhibition of return in single and dual tasks: Examining saccadic, keypress, and pointing responses Journal Article In: Perception and Psychophysics, vol. 70, no. 2, pp. 257–265, 2008. @article{Pratt2008,Two experiments are reported in which inhibition of return (IOR) was examined with single-response tasks (ither manual responses alone or saccadic responses alone) and dual-response tasks (simultaneous manual and saccadic responses). The first experiment—using guided limb movements that require considerable spatial information—showed more IOR for saccades than for pointing responses. In addition, saccadic IOR was reduced with concurrent pointing movements, but manual IOR was not affected by concurrent saccades. Importantly, at the time of saccade initiation, the arm movements did not start yet, indicating that the influence on saccade IOR is due to arm-movement preparation. In the second experiment, using localization keypress responses that required only minimal spatial information, greater IOR was again found for saccadic than for manual responses, but no effect of concurrent movements was found. These findings add further support that there is a dissociation between oculomotor and skeletal-motor IOR. Moreover, the results show that the preparation manual responses tend to mediate saccadic behavior—but only when the manual responses require high levels of spatial accuracy—and that the superior colliculus is the likely neural substrate integrating IOR for eye and arm movements. |
Alexander Pollatsek; Timothy J. Slattery; Barbara J. Juhasz The processing of novel and lexicalised prefixed words in reading Journal Article In: Language and Cognitive Processes, vol. 23, no. 7-8, pp. 1133–1158, 2008. @article{Pollatsek2008,Two experiments compared how relatively long novel prefixed words (e.g., overfarm) and existing prefixed words were processed in reading. The use of novel prefixed words allows one to examine the roles of whole-word access and decompositional processing in the processing of non-novel prefixed words. The two experiments found that, although there was a large cost to novelty (e.g., gaze durations were about 100 ms longer for novel prefixedwords), the effect of the frequency of the root morpheme on fixation measures was about the same for novel and non-novel prefixed words for most measures. This finding rules out a (‘‘horse-race'') dual-route model of processing for existing prefixed words in which the whole-word and decompositional route are parallel and independent, as such a model would predict a substantially larger root frequency effect for novel words (where whole-word processes do not exist). The most likely model to explain the processing of prefixed words is a parallel interactive one. |
Archana Pradeep; Shery Thomas; Eryl O. Roberts; Frank A. Proudlock; Irene Gottlob Reduction of congenital nystagmus in a patient after smoking cannabis Journal Article In: Strabismus, vol. 16, no. 1, pp. 29–32, 2008. @article{Pradeep2008,INTRODUCTION: Smoking cannabis has been described to reduce acquired pendular nystagmus in MS, but its effect on congenital nystagmus is not known. PURPOSE: To report the effect of smoking cannabis in a case of congenital nystagmus. METHODS: A 19-year-old male with congenital horizontal nystagmus presented to the clinic after smoking 10 mg of cannabis. He claimed that the main reason for smoking cannabis was to improve his vision. At the next clinic appointment, he had not smoked cannabis for 3weeks. Full ophthalmologic examination and eye movement recordings were performed at each visit. RESULTS: Visual acuity improved by 3 logMar lines in the left eye and by 2 logMar lines in the right eye after smoking cannabis. The nystagmus intensities were reduced by 30% in primary position and 44%, 11%, 10% and 40% at 20-degree eccentricity to the right, left, elevation and depression, respectively, after smoking cannabis. CONCLUSION: Cannabis may be beneficial in the treatment of congenital idiopathic nystagmus (CIN). Further research to clarify the safety and efficacy of cannabis in patients with CIN, administered for example by capsules or spray, would be important. |
Heinz-Werner Priess; Sabine Born; Ulrich Ansorge Inhibition of return after color singletons Journal Article In: Journal of Eye Movement Research, vol. 5, no. 5, pp. 1–12, 2008. @article{Priess2008,Inhibition of return (IOR) is the faster selection of hitherto unattended than previously attended positions. Some previous studies failed to find evidence for IOR after attention capture by color singletons. Others, however, did report IOR effects after color singletons. The current study examines the role of cue relevance for obtaining IOR effects. By using a potentially more sensitive method - saccadic IOR - we tested and found IOR after relevant color singleton cues that required an attention shift (Experiment 1). In contrast, irrelevant color singletons failed to produce reliable IOR effects in Experiment 2. Also, Experiment 2 rules out an alternative explanation of our IOR findings in terms of masking. We discuss our results in light of pertaining theories of IOR. |
Cliodhna Quigley; Selim Onat; Sue Harding; Martin Cooke; Peter König Audio-visual integration during overt visual attention Journal Article In: Journal of Eye Movement Research, vol. 1, no. 2, pp. 4, 2008. @article{Quigley2008,How do different sources of information arising from different modalities interact to control where we look? To answer this question with respect to real-world operational conditions we presented natural images and spatially localized sounds in (V)isual, Audiovisual (AV) and (A)uditory conditions and measured subjects' eye-movements. Our results demonstrate that eye-movements in AV conditions are spatially biased towards the part of the image corresponding to the sound source. Interestingly, this spatial bias is dependent on the probability of a given image region to be fixated (saliency) in the V condition. This indicates that fixation behaviour during the AV conditions is the result of an integration process. Regression analysis shows that this integration is best accounted for by a linear combination of unimodal saliencies. |
Ralph Radach; Lynn Huestegge; Ronan G. Reilly The role of global top-down factors in local eye-movement control in reading Journal Article In: Psychological Research, vol. 72, no. 6, pp. 675–688, 2008. @article{Radach2008,Although the development of the field of reading has been impressive, there are a number of issues that still require much more attention. One of these concerns the variability of skilled reading within the individual. This paper explores the topic in three ways: (1) it quantifies the extent to which, two factors, the specific reading task (comprehension vs. word verification) and the format of reading material (sentence vs. passage) influence the temporal aspects of reading as expressed in word-viewing durations; (2) it examines whether they also affect visuomotor aspects of eye-movement control; and (3) determine whether they can modulate local lexical processing. The results reveal reading as a dynamic, interactive process involving semi-autonomous modules, with top-down influences clearly evident in the eye-movement record. |
Christoph Rasche; Karl R. Gegenfurtner Orienting during gaze guidance in a letter-identification task Journal Article In: Journal of Eye Movement Research, vol. 3, no. 4, pp. 1–10, 2008. @article{Rasche2008,The idea of gaze guidance is to lead a viewer's gaze through a visual display in order to facilitate the viewer's search for specific information in a least-obtrusive manner. This study investigates saccadic orienting when a viewer is guided in a fast-paced, low-contrast letter identification task. Despite the task's difficulty and although guiding cues were ad-justed to gaze eccentricity, observers preferred attentional over saccadic shifts to obtain a letter identification judgment; and if a saccade was carried out its saccadic constant error was 50%. From those results we derive a number of design recommendations for the process of gaze guidance. |
Leah Roberts; Marianne Gullberg; Peter Indefrey Online pronoun resolution in L2 discouse: L1 influence and general learner effects Journal Article In: Studies in Second Language Acquisition, vol. 30, pp. 333–357, 2008. @article{Roberts2008,This study investigates whether advanced second language (L2) learners of a nonnull subject language (Dutch) are influenced by their null subject first language (L1) (Turkish) in their offline and online resolution of subject pronouns in L2 discourse. To tease apart potential L1 effects from possible general L2 processing effects, we also tested a group of German L2 learners of Dutch who were predicted to perform like the native Dutch speakers. The two L2 groups differed in their offline interpretations of subject pronouns. The Turkish L2 learners exhibited a L1 influence, because approximately half the time they interpreted Dutch subject pronouns as they would overt pronouns in Turkish, whereas the German L2 learners performed like the Dutch controls, interpreting pronouns as coreferential with the current discourse topic. This L1 effect was not in evidence in eye-tracking data, however. Instead, the L2 learners patterned together, showing an online processing disadvantage when two potential antecedents for the pronoun were grammatically available in the discourse. This processing disadvantage was in evidence irrespective of the properties of the learners' L1 or their final interpretation of the pronoun. Therefore, the results of this study indicate both an effect of the L1 on the L2 in offline resolution and a general L2 processing effect in online subject pronoun resolution. |
Anne Roefs; Anita Jansen; Sofie Moresi; Paul Willems; Sarah Grootel; Anouk Borgh Looking good: BMI, attractiveness bias and visual attention. Journal Article In: Appetite, vol. 51, pp. 552–555, 2008. @article{Roefs2008,The aim of this study was to study attentional bias when viewing one's own and a control body, and to relate this bias to body-weight and attractiveness ratings. Participants were 51 normal-weight female students with an unrestrained eating style. They were successively shown pictures of their own and a control body for 30s each, while their eye movements (overt attention) were being measured. Afterwards, participants were asked to identify the most attractive and most unattractive body part of both their own and a control body. The results show that with increasing BMI and where an individual has given a relatively low rating of attractiveness to their own body, participants attended relatively more to their self-identified most unattractive body part and the control body's most attractive body part. This increasingly negative bias in visual attention for bodies may maintain and/or exacerbate body dissatisfaction. |
Ardi Roelofs Tracing attention and the activation flow in spoken word planning using eye movements Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 34, no. 2, pp. 353–368, 2008. @article{Roelofs2008,The flow of activation from concepts to phonological forms within the word production system was examined in 3 experiments. In Experiment 1, participants named pictures while ignoring superimposed distractor pictures that were semantically related, phonologically related, or unrelated. Eye movements and naming latencies were recorded. The distractor pictures affected the latencies of gaze shifting and vocal naming. The magnitude of the phonological effects increased linearly with latency, excluding lapses of attention as the cause of the effects. In Experiment 2, no distractor effects were obtained when both pictures were named. When pictures with superimposed distractor words were named or the words were read in Experiment 3, the words influenced the latencies of gaze shifting and picture naming, but the pictures yielded no such latency effects in word reading. The picture-word asymmetry was obtained even with equivalent reading and naming latencies. The picture-picture effects suggest that activation spreads continuously from concepts to phonological forms, whereas the picture-word asymmetry indicates that the amount of activation is limited and task dependent. |
Ardi Roelofs Attention, gaze shifting, and dual-task interference from phonological encoding in spoken word planning Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 34, no. 6, pp. 1580–1598, 2008. @article{Roelofs2008a,Controversy exists about whether dual-task interference from word planning reflects structural bottleneck or attentional control factors. Here, participants named pictures whose names could or could not be phonologically prepared, and they manually responded to arrows presented away from (Experiment 1), or superimposed onto, the pictures (Experiments 2 and 3); or they responded to tones (Experiment 4). Pictures and arrows/tones were presented at stimulus onset asynchronies of 0, 300, and 1,000 ms. Earlier research showed that vocal responding hampers auditory perception, which predicts earlier shifts of attention to the tones than to the arrows. Word planning yielded dual-task interference. Phonological preparation reduced the latencies of picture naming and gaze shifting. The preparation benefit was propagated into the latencies of the manual responses to the arrows but not to the tones. The malleability of the interference supports the attentional control account. This conclusion was corroborated by computer simulations showing that an extension of WEAVER++ (A. Roelofs, 2003) with assumptions about the attentional control of tasks quantitatively accounts for the latencies of vocal responding, gaze shifting, and manual responding. |
Martin Rolfs; Reinhold Kliegl; Ralf Engbert Toward a model of microsaccade generation: The case of microsaccadic inhibition Journal Article In: Journal of Vision, vol. 8, no. 11, pp. 1–23, 2008. @article{Rolfs2008a,Microsaccades are one component of the small eye movements that constitute fixation. Their implementation in the oculomotor system is unknown. To better understand the physiological and mechanistic processes underlying microsaccade generation, we studied microsaccadic inhibition, a transient drop of microsaccade rate, in response to irrelevant visual and auditory stimuli. Quantitative descriptions of the time course and strength of inhibition revealed a strong dependence of microsaccadic inhibition on stimulus characteristics. In Experiment 1, microsaccadic inhibition occurred sooner after auditory than after visual stimuli and after luminance-contrast than after color-contrast visual stimuli. Moreover, microsaccade amplitude strongly decreased during microsaccadic inhibition. In Experiment 2, the latency of microsaccadic inhibition increased with decreasing luminance contrast. We develop a conceptual model of microsaccade generation in which microsaccades result from fixation-related activity in a motor map coding for both fixation and saccades. In this map, fixation is represented at the central site. Saccades are generated by activity in the periphery, their amplitude increasing with eccentricity. The activity at the central, fixation-related site of the map predicts the rate of microsaccades as well as their amplitude and direction distributions. This model represents a framework for understanding the dynamics of microsaccade behavior in a broad range of tasks. |
Martin Rolfs; Jochen Laubrock; Reinhold Kliegl Microsaccade-induced prolongation of saccadic latencies depends on microsaccade amplitude Journal Article In: Journal of Eye Movement Research, vol. 1, no. 3, pp. 1–8, 2008. @article{Rolfs2008,Fixations consist of small movements including microsaccades, i.e., rapid flicks in eye position that replace the retinal image by up to 1 degree of visual angle. Recently, we showed in a delayed-saccade task (1) that the rate of microsaccades decreased in the course of saccade preparation and (2) that microsaccades occurring around the time of a go signal were associated with prolonged saccade latencies (Rolfs et al., 2006). A re-analysis of the same data set revealed a strong dependence of these findings on microsaccade amplitude. First, microsaccade amplitude dropped to a minimum just before the generation of a saccade. Second, the delay of response saccades was a function of microsaccade amplitude: Microsaccades with larger amplitudes were followed by longer response latencies. These finding were predicted by a recently proposed model that attributes microsaccade generation to fixation-related activity in a saccadic motor map that is in competition with the generation of large saccades (Rolfs et al., 2008). We propose, therefore, that microsaccade statistics provide a behavioral correlate of fixation-related activity in the oculomotor system. |
N. N. J. Rommelse; Stefan Van der Stigchel; J. Witlox; C. J. A. Geldof; J. -B. Deijen; Jan Theeuwes; Jaap Oosterlaan; J. A. Sergeant Deficits in visuo-spatial working memory, inhibition and oculomotor control in boys with ADHD and their non-affected brothers Journal Article In: Journal of Neural Transmission, vol. 115, no. 2, pp. 249–260, 2008. @article{Rommelse2008,Few studies have assessed visuo-spatial working memory and inhibition in attention-deficit/hyperactivity disorder (ADHD) by recording saccades and consequently little additional knowledge has been gathered on oculomotor functioning in ADHD. Moreover, this is the first study to report the performance of non-affected siblings of children with ADHD, which may shed light on the familiality of deficits. A total of 14 boys with ADHD, 18 non-affected brothers, and 15 control boys aged 7-14 years, were administered a memory-guided saccade task with delays of three and seven seconds. Familial deficits were found in accuracy of visuo-spatial working memory, percentage of anticipatory saccades, and tendency to overshoot saccades relative to controls. These findings suggest memory-guided saccade deficits may relate to a familial predisposition for ADHD. |
Alicia Peltsch; Aaron B. Hoffman; I. T. Armstrong; Giovanna Pari; D. P. Munoz Saccadic impairments in Huntington's disease Journal Article In: Experimental Brain Research, vol. 186, no. 3, pp. 457–469, 2008. @article{Peltsch2008,Huntington's disease (HD), a progressive neurological disorder involving degeneration in basal ganglia structures, leads to abnormal control of saccadic eye movements. We investigated whether saccadic impairments in HD (N = 9) correlated with clinical disease severity to determine the relationship between saccadic control and basal ganglia pathology. HD patients and age/sex-matched controls performed various eye movement tasks that required the execution or suppression of automatic or voluntary saccades. In the "immediate" saccade tasks, subjects were instructed to look either toward (pro-saccade) or away from (anti-saccade) a peripheral stimulus. In the "delayed" saccade tasks (pro-/anti-saccades; delayed memory-guided sequential saccades), subjects were instructed to wait for a central fixation point to disappear before initiating saccades towards or away from a peripheral stimulus that had appeared previously. In all tasks, mean saccadic reaction time was longer and more variable amongst the HD patients. On immediate anti-saccade trials, the occurrence of direction errors (pro-saccades initiated toward stimulus) was higher in the HD patients. In the delayed tasks, timing errors (eye movements made prior to the go signal) were also greater in the HD patients. The increased variability in saccadic reaction times and occurrence of errors (both timing and direction errors) were highly correlated with disease severity, as assessed with the Unified Huntington's Disease Rating Scale, suggesting that saccadic impairments worsen as the disease progresses. Thus, performance on voluntary saccade paradigms provides a sensitive indicator of disease progression in HD. |
Angélica Pérez Fornos; Jörg Sommerhalder; Alexandre Pittard; Avinoam B. Safran; Marco Pelizzone Simulation of artificial vision: IV. Visual information required to achieve simple pointing and manipulation tasks Journal Article In: Vision Research, vol. 48, no. 16, pp. 1705–1718, 2008. @article{PerezFornos2008,Retinal prostheses attempt to restore some amount of vision to totally blind patients. Vision evoked this way will be however severely constrained because of several factors (e.g., size of the implanted device, number of stimulating contacts, etc.). We used simulations of artificial vision to study how such restrictions of the amount of visual information provided would affect performance on simple pointing and manipulation tasks. Five normal subjects participated in the study. Two tasks were used: pointing on random targets (LEDs task) and arranging wooden chips according to a given model (CHIPs task). Both tasks had to be completed while the amount of visual information was limited by reducing the resolution (number of pixels) and modifying the size of the effective field of view. All images were projected on a 10° × 7° viewing area, stabilised at a given position on the retina. In central vision, the time required to accomplish the tasks remained systematically slower than with normal vision. Accuracy was close to normal at high image resolutions and decreased at 500 pixels or below, depending on the field of view used. Subjects adapted quite rapidly (in less than 15 sessions) to performing both tasks in eccentric vision (15° in the lower visual field), achieving after adaptation performances close to those observed in central vision. These results demonstrate that, if vision is restricted to a small visual area stabilised on the retina (as would be the case in a retinal prosthesis), the perception of several hundreds of retinotopically arranged phosphenes is still needed to restore accurate but slow performance on pointing and manipulation tasks. Considering that present prototypes afford less than 100 stimulation contacts and that our simulations represent the most favourable visual input conditions that the user might experience, further development is required to achieve optimal rehabilitation prospects. |
Matthew S. Peterson; Melissa R. Beck; Jason H. Wong Were you paying attention to where you looked? The role of executive working memory in visual search Journal Article In: Psychonomic Bulletin & Review, vol. 15, no. 2, pp. 372–377, 2008. @article{Peterson2008,Recent evidence has indicated that performing a working memory task that loads executive working memory leads to less efficient visual search (Han & Kim, 2004). We explored the role that executive functioning plays in visual search by examining the pattern of eye movements while participants performed a search task with or without a secondary executive working memory task. Results indicate that executive functioning plays two roles in visual search: the identification of objects and the control of the disengagement of attention. |
Tobias Pflugshaupt; Thomas Nyffeler; Roman Von Wartburg; Christian W. Hess; René M. Müri Loss of exploratory vertical saccades after unilateral frontal eye field damage Journal Article In: Journal of Neurology, Neurosurgery and Psychiatry, vol. 79, no. 4, pp. 474–477, 2008. @article{Pflugshaupt2008,Despite their relevance for locomotion and social interaction in everyday situations, little is known about the cortical control of vertical saccades in humans. Results from microstimulation studies indicate that both frontal eye fields (FEFs) contribute to these eye movements. Here, we present a patient with a damaged right FEF, who hardly made vertical saccades during visual exploration. This finding suggests that, for the cortical control of exploratory vertical saccades, integrity of both FEFs is indeed important. |
Matthew H. Phillips; Jay A. Edelman The dependence of visual scanning performance on search direction and difficulty Journal Article In: Vision Research, vol. 48, no. 21, pp. 2184–2192, 2008. @article{Phillips2008,Phillips and Edelman [Phillips, M. H., & Edelman, J. A. (2008). The dependence of visual scanning performance on saccade, fixation, and perceptual metrics. Vision Research, 48(7), 926-936] presented evidence that performance variability in a visual scanning task depends on oculomotor variables related to saccade amplitude rather than fixation duration, and that saccade-related metrics reflects perceptual span. Here, we extend these results by showing that even for extremely difficult searches trial-to-trial performance variability still depends on saccade-related metrics and not fixation duration. We also show that scanning speed is faster for horizontal than for vertical searches, and that these differences derive again from differences in saccade-based metrics and not from differences in fixation duration. We find perceptual span to be larger for horizontal than vertical searches, and approximately symmetric about the line of gaze. |
Elmar H. Pinkhardt; Reinhart Jürgens; Wolfgang Becker; Federica Valdarno; Albert C. Ludolph; Jan Kassubek Differential diagnostic value of eye movement recording in PSP-parkinsonism, Richardson's syndrome, and idiopathic Parkinson's disease Journal Article In: Journal of Neurology, vol. 255, no. 12, pp. 1916–1925, 2008. @article{Pinkhardt2008,Vertical gaze palsy is a highly relevant clinical sign in parkinsonian syndromes. As the eponymous sign of progressive supranuclear palsy (PSP), it is one of the core features in the diagnosis of this disease. Recent studies have suggested a further differentiation of PSP in Richardson's syndrome (RS) and PSP-parkinsonism (PSPP). The aim of this study was to search for oculomotor abnormalities in the PSP-P subset of a sample of PSP patients and to compare these findings with those of (i) RS patients, (ii) patients with idiopathic Parkinson's disease (IPD), and (iii) a control group. Twelve cases of RS, 5 cases of PSP-P, and 27 cases of IPD were examined by use of video-oculography (VOG) and compared to 23 healthy normal controls. Both groups of PSP patients (RS, PSP-P) had significantly slower saccades than either IPD patients or controls, whereas no differences in saccadic eye peak velocity were found between the two PSP groups or in the comparison of IPD with controls. RS and PSP-P were also similar to each other with regard to smooth pursuit eye movements (SPEM), with both groups having significantly lower gain than controls (except for downward pursuit); however, SPEM gain exhibited no consistent difference between PSP and IPD. A correlation between eye movement data and clinical data (Hoehn & Yahr scale or disease duration) could not be observed. As PSP-P patients were still in an early stage of the disease when a differentiation from IPD is difficult on clinical grounds, the clear-cut separation between PSP-P and IPD obtained by measuring saccade velocity suggests that VOG could contribute to the early differentiation between these patient groups. |
Keith Rayner; Brett Miller; Caren M. Rotello Eye movements when looking at print advertisements: The goal of the viewer matters Journal Article In: Applied Cognitive Psychology, vol. 22, no. 5, pp. 697–707, 2008. @article{Rayner2008,Viewers looked at print advertisements as their eye movements were recorded. Half of them were asked to rate how much they liked each ad (for convenience, we will generally use the term 'ad' from this point on), while the other half were asked to rate the effectiveness of each ad. Previous research indicated that viewers who were asked to consider purchasing products in the ads looked at the text earlier and more often than the picture part of the ad. In contrast, viewers in the present experiment looked at the picture part of the ad earlier and longer than the text. The results indicate quite clearly that the goal of the viewer very much influences where (and for how long) viewers look at different parts of ads, but also indicate that the nature of the ad per se matters. |
Paul Reeve; James J. Clark; J. Kevin O'Regan Convergent flash localization near saccades without equivalent "compression" of perceived separation Journal Article In: Journal of Vision, vol. 8, no. 13, pp. 1–19, 2008. @article{Reeve2008,Visual space is sometimes said to be "compressed" before saccadic eye movements. The most central evidence for this hypothesis is a converging pattern of localization errors on single flashes presented close to saccade time under certain conditions. An intuitive version of the compression hypothesis predicts that the reported distance between simultaneous, spatially separated presaccadic flashes should contract in the same way as their individual locations. In our experiment we tested this prediction by having subjects perform one of two tasks on stimuli made up of two bars simultaneously flashed near saccade time: either localizing one of the bars or judging the separation between the two. Localization judgments showed the previously observed converging pattern over the 50-100 ms before saccades. Contractions in perceived separation between the two bars were not accurately predicted by this pattern: they occurred mainly during saccades and were much weaker than convergence in localization. Different forms of spatial information about flashed stimuli can be differentially modulated before, during, and after saccades. Structural alterations in the perceptual field around saccades may explain these different effects, but alternative hypotheses based on decision making under uncertainty and on the influence of other perisaccadic mechanisms are also consistent with this and other evidence. |
Erik D. Reichle; Polina M. Vanyukov; Patryk A. Laurent; Tessa Warren Serial or parallel? Using depth-of-processing to examine attention allocation during reading Journal Article In: Vision Research, vol. 48, no. 17, pp. 1831–1836, 2008. @article{Reichle2008,This paper presents an experiment investigating attention allocation in four tasks requiring varied degrees of lexical processing of 1-4 simultaneously displayed words. Response times and eye movements were only modestly affected by the number of words in an asterisk-detection task but increased markedly with the number of words in letter-detection, rhyme-judgment, and semantic-judgment tasks, suggesting that attention may not be serial for tasks that do not require significant lexical processing (e.g., detecting visual features), but is approximately serial for tasks that do (e.g., retrieving word meanings). The implications of these results for models of readers' eye movements are discussed. |
Kathleen Pirog Revill; Michael K. Tanenhaus; Richard N. Aslin Context and spoken word recognition in a novel lexicon Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 34, no. 5, pp. 1207–1223, 2008. @article{Revill2008,Three eye movement studies with novel lexicons investigated the role of semantic context in spoken word recognition, contrasting 3 models: restrictive access, access–selection, and continuous integration. Actions directed at novel shapes caused changes in motion (e.g., looming, spinning) or state (e.g., color, texture). Across the experiments, novel names for the actions and the shapes varied in frequency, cohort density, and whether the cohorts referred to actions (Experiment 1) or shapes with action-congruent or action-incongruent affordances (Experiments 2 and 3). Experiment 1 demonstrated effects of frequency and cohort competition from both displayed and non-displayed competitors. In Experiment 2, a biasing context induced an increase in anticipatory eye movements to congruent referents and reduced the probability of looks to incongruent cohorts, without the delay predicted by access–selection models. In Experiment 3, context did not reduce competition from non-displayed incompatible neighbors as predicted by restrictive access models. The authors conclude that the results are most consistent with continuous integration models. |
Frédéric P. Rey; Thanh Thuan Lê; René Bertin; Zoï Kapoula Saccades horizontal or vertical at near or at far do not deteriorate postural control Journal Article In: Auris Nasus Larynx, vol. 35, no. 2, pp. 185–191, 2008. @article{Rey2008,Objective: There is a discrepancy about the effect of saccades on postural control: some studies reported a stabilization effect, other studies the opposite. Perturbation of posture by saccades could be related to loss of vision during saccades (saccades suppression) due to high velocity retinal slip. On the other hand, efferent and afferent proprioceptive signals related to saccades can be used for obtaining spatial stability over saccades and maintaining good postural control. In natural conditions saccades can be horizontal, vertical and made at different distance. The present study examines all these parameters to provide a more complete view on the role of saccade on postural control in quiet stance. Methods: Horizontal or vertical saccades of 30° were made at 1 Hz and at two distances, 40 and 200 cm. Eye movements were recorded with video-oculograhpy (EyeLink II). Posturography was recorded with the TechnoConcept platform. The results from "saccade" conditions are compared to "fixation control" condition (at far and near). Results: The video oculography results show that subjects performed the fixation or the saccade task correctly. Execution of saccades (horizontal or vertical at near or at far distance) had no significant effect on the surface of center of pressure (CoP), neither on the standard deviation of the lateral body sway, nor on the variance of speed of the CoP. Moreover, whatever the distance, execution of saccades decreased significantly the standard deviation of the antero-posterior sway. Conclusion: We conclude that saccades, of either the direction and at either the distance, do not deteriorate postural control; rather they could reduce sway. Efferent and proprioceptive oculomotor signals as well as attention could contribute to maintain or improve postural stability while making saccades. |
Tamara A. Russell; Melissa J. Green; Ian Simpson; Max Coltheart Remediation of facial emotion perception in schizophrenia: Concomitant changes in visual attention Journal Article In: Schizophrenia Research, vol. 103, no. 1-3, pp. 248–256, 2008. @article{Russell2008,The study examined changes in visual attention in schizophrenia following training with a social-cognitive remediation package designed to improve facial emotion recognition (the Micro-Expression Training Tool; METT). Forty out-patients with schizophrenia were randomly allocated to active training (METT; n = 26), or repeated exposure (RE; n = 14); all completed an emotion recognition task with concurrent eye movement recording. Emotion recognition accuracy was significantly improved in the METT group, and this effect was maintained after one week. Immediately following training, the METT group directed more eye movements within feature areas of faces (i.e., eyes, nose, mouth) compared to the RE group. The number of fixations directed to feature areas of faces was positively associated with emotion recognition accuracy prior to training. After one week, the differences between METT and RE groups in viewing feature areas of faces were reduced to trends. However, within group analyses of the METT group revealed significantly increased number of fixations to, and dwell time within, feature areas following training which were maintained after one week. These results provide the first evidence that improvements in emotion recognition following METT training are associated with changes in visual attention to the feature areas of emotional faces. These findings support the contribution of visual attention abnormalities to emotion recognition impairment in schizophrenia, and suggest that one mechanism for improving emotion recognition involves re-directing visual attention to relevant features of emotional faces. |
Thomas Geyer; Hermann J. Müller; Joseph Krummenacher Expectancies modulate attentional capture by salient color singletons Journal Article In: Vision Research, vol. 48, no. 11, pp. 1315–1326, 2008. @article{Geyer2008,In singleton feature search for a form-defined target, the presentation of a task-irrelevant, but salient singleton color distractor is known to interfere with target detection [Theeuwes, J. (1991). Cross-dimensional perceptual selectivity. Perception & Psychophysics, 50, 184-193; Theeuwes, J. (1992). Perceptual selectivity for color and form. Perception & Psychophysics, 51, 599-606]. The present study was designed to re-examine this effect, by presenting observers with a singleton form target (on each trial) that could be accompanied by a salient) singleton color distractor, with the proportion of distractor to no-distractor trials systematically varying across blocks of trials. In addition to RTs, eye movements were recorded in order to examine the mechanisms underlying the distractor interference effect. The results showed that singleton distractors did interfere with target detection only when they were presented on a relatively small (but not on a large) proportion of trials. Overall, the findings suggest that cross-dimensional interference is a covert attention effect, arising from the competition of the target with the distractor for attentional selection [Kumada, T., & Humphreys, G. W. (2002). Cross-dimensional interference and cross-trial inhibition. Perception & Psychophysics, 64, 493-503], with the strength of the competition being modulated by observers' (top-down) incentive to suppress the distractor dimension. |
Richard Godijn; Arthur F. Kramer Oculomotor capture by surprising onsets Journal Article In: Visual Cognition, vol. 16, no. 2-3, pp. 279–289, 2008. @article{Godijn2008b,The present study examined the effect of surprising onsets on oculomotor behaviour. Participants were required to execute a saccadic eye movement to a colour singleton target. After a series of trials an unexpected onset distractor was abruptly presented on the surprise trial. The presentation of the onset was repeated on subsequent trials. The results showed that the onset captured the eyes for 28% of the participants on the surprise trial, but this percentage decreased after repeated exposure to the onset. Furthermore, saccade latencies to the target were increased when a surprising onset was presented. After repeated exposure to the onset, latencies to the target decreased to the preonset level. The results suggest that when the onset is not part of participants' task set it has a strong effect on oculomotor behaviour. Once the task set has been updated and the onset no longer comes as a surprise its effect on oculomotor behaviour is dramatically reduced. |
Jennifer J. Heisz; David I. Shore More efficient scanning for familiar faces Journal Article In: Journal of Vision, vol. 8, no. 1, pp. 1–10, 2008. @article{Heisz2008,The present study reveals changes in eye movement patterns as newly learned faces become more familiar. Observers received multiple exposures to newly learned faces over four consecutive days. Recall tasks were performed on all 4 days, and a recognition task was performed on the fourth day. Eye movement behavior was compared across facial exposure and task type. Overall, the eyes were viewed for longer and more often than any other facial region, regardless of face familiarity. As a face became more familiar, observers made fewer fixations during recall and recognition. With increased exposure, observers sampled more from the eyes and sampled less from the nose, mouth, forehead, chin, and cheek regions. Interestingly, this change in scanning behavior was only observed for recall tasks, but not for recognition. |
Jens R. Helmert; Sebastian Pannasch; Boris M. Velichkovsky Influences of dwell time and cursor control on the performance in gaze driven typing Journal Article In: Journal of Eye Movement Research, vol. 2, no. 1, pp. 1–8, 2008. @article{Helmert2008,In gaze controlled computer interfaces the dwell time is often used as selection criterion. But this solution comes along with several problems, especially in the temporal domain: Eye movement studies on scene perception could demonstrate that fixations of different durations serve different purposes and should therefore be differentiated. The use of dwell time for selection implies the need to distinguish intentional selections from merely per-ceptual processes, described as the Midas touch problem. Moreover, the feedback of the actual own eye position has not yet been addressed to systematic studies in the context of usability in gaze based computer interaction. We present research on the usability of a simple eye typing set up. Different dwell time and eye position feedback configurations were tested. Our results indicate that smoothing raw eye position and temporal delays in visual feedback enhance the system's functionality and usability. Best overall performance was obtained with a dwell time of 500 ms. |
John M. Henderson; Graham L. Pierce Eye movements during scene viewing: Evidence for mixed control of fixation durations Journal Article In: Psychonomic Bulletin & Review, vol. 15, no. 3, pp. 566–573, 2008. @article{Henderson2008,Recent behavioral and computational research on eye movement control during scene viewing has focused on where the eyes move. However, fixations also differ in their durations, and when the eyes move may be another important indicator of perceptual and cognitive activity. Here we used a scene onset delay paradigm to investigate the degree to which individual fixation durations are under direct moment-to-moment control of the viewer's current visual scene. During saccades just prior to critical fixations, the scene was removed from view so that when the eyes landed, no scene was present. Following a manipulated delay period, the scene was restored to view. We found that one population of fixations was under the direct control of the current scene, increasing in duration as delay increased. A second population of fixations was relatively constant across delay. The pattern of data did not change whether delay duration was random or blocked, suggesting that the effects were not under the strategic control of the viewer. The results support a mixed control model in which the durations of some fixations proceed regardless of scene presence, whereas others are under the direct moment-to-moment control of ongoing scene analysis. |
Teresa D. Hernandez; Carmel A. Levitan; Martin S. Banks; Clifton M. Schor How does saccade adaptation affect visual perception? Journal Article In: Journal of Vision, vol. 8, no. 8, pp. 1–16, 2008. @article{Hernandez2008,Three signals are used to visually localize targets and stimulate saccades: (1) retinal location signals for intended saccade amplitude, (2) sensory-motor transform (SMT) of retinal signals to extra-ocular muscle innervation, and (3) estimates of eye position from extra-retinal signals. We investigated effects of adapting saccade amplitude to a double-step change in target location on perceived direction. In a flashed-pointing task, subjects pointed an unseen hand at a briefly displayed eccentric target without making a saccade. In a sustained-pointing task, subjects made a horizontal saccade to a double-step target. One second after the second step, they pointed an unseen hand at the final target position. After saccade-shortening adaptation, there was little change in hand-pointing azimuth toward the flashed target suggesting that most saccade adaptation was caused by changes in the SMT. After saccade-lengthening adaptation, there were small changes in hand-pointing azimuth to flashed targets, indicating that 1/3 of saccade adaptation was caused by changes in estimated retinal location signals and 2/3 by changes in the SMT. The sustained hand-pointing task indicated that estimates of eye position adapted inversely with changes of the SMT. Changes in perceived direction resulting from saccade adaptation are mainly influenced by extra-retinal factors with a small retinal component in the lengthening condition. |
Lee Hogarth; Anthony Dickinson; Alison Austin; Craig Brown; Theodora Duka Attention and expectation in human predictive learning: The role of uncertainty Journal Article In: Quarterly Journal of Experimental Psychology, vol. 61, no. 11, pp. 1658–1668, 2008. @article{Hogarth2008,Three localized, visual pattern stimuli were trained as predictive signals of auditory outcomes. One signal partially predicted an aversive noise in Experiment 1 and a neutral tone in Experiment 2, whereas the other signals consistently predicted either the occurrence or absence of the noise. The expectation of the noise was measured during each signal presentation, and only participants for whom this expectation demonstrated contingency knowledge showed differential attention to the signals. Importantly, when attention was measured by visual fixations, the contingency-aware group attended more to the partially predictive signal than to the consistent predictors in both experiments. This profile of visual attention supports the Pearce and Hall (1980) theory of the role of attention in associative learning. |
Lee Hogarth; Anthony Dickinson; Molly Janowski; Aleksandra Nikitina; Theodora Duka The role of attentional bias in mediating human drug-seeking behaviour Journal Article In: Psychopharmacology, vol. 201, no. 1, pp. 29–41, 2008. @article{Hogarth2008a,RATIONALE: The attentional bias for drug cues is believed to be a causal cognitive process mediating human drug seeking and relapse. OBJECTIVES, METHODS AND RESULTS: To test this claim, we trained smokers on a tobacco conditioning procedure in which the conditioned stimulus (or S+) acquired parallel control of an attentional bias (measured with an eye tracker), tobacco expectancy and instrumental tobacco-seeking behaviour. Although this correlation between measures may be regarded as consistent with the claim that the attentional bias for the S+ mediated tobacco seeking, when a secondary task was added in the test phase, the attentional bias for the S+ was abolished, yet the control of tobacco expectancy and tobacco seeking remained intact. CONCLUSIONS: This dissociation suggests that the attentional bias for drug cues is not necessary for the control that drug cues exert over drug-seeking behaviour. The question raised by these data is what function does the attentional bias serve if it does not mediate drug seeking? |
Robert D. Gordon; Sarah D. Vollmer; Megan L. Frankl Object continuity and the transsaccadic representation of form Journal Article In: Perception and Psychophysics, vol. 70, no. 4, pp. 667–679, 2008. @article{Gordon2008,Transsaccadic object file representations were investigated in three experiments. Subjects moved their eyes from a central fixation cross to a location between two peripheral objects. During the saccade, this preview display was replaced with a target display containing a single object to be named. On trials on which the target identity matched one of the preview objects, its orientation either matched or did not match the previewed orientation. The results of Experiments 1 and 2 revealed that orientation changes disrupt perceptual continuity for objects located near fixation, but not for objects located further from fixation. The results of Experiment 3 confirmed that orientation changes do not disrupt continuity for distant objects, while showing that subjects nevertheless maintain an object-specific representation of the orientation of such objects. Together, the results suggest that object files represent orientation but that whether or not orientation plays a role in the processes that determine continuity depends on the quality of the perceptual representation. While |
Melissa J. Green; Jennifer H. Waldron; Ian Simpson; Max Coltheart Visual processing of social context during mental state perception in schizophrenia Journal Article In: Journal of Psychiatry and Neuroscience, vol. 33, no. 1, pp. 34–42, 2008. @article{Green2008,OBJECTIVE: To examine schizophrenia patients' visual attention to social contextual information during a novel mental state perception task. METHOD: Groups of healthy participants (n = 26) and schizophrenia patients (n = 24) viewed 7 image pairs depicting target characters presented context-free and context-embedded (i.e., within an emotion-congruent social context). Gaze position was recorded with the EyeLink I Gaze Tracker while participants performed a mental state inference task. Mean eye movement variables were calculated for each image series (context-embedded v. context-free) to examine group differences in social context processing. RESULTS: The schizophrenia patients demonstrated significantly fewer saccadic eye movements when viewing context-free images and significantly longer eye-fixation durations when viewing context-embedded images. Healthy individuals significantly shortened eye-fixation durations when viewing context-embedded images, compared with context-free images, to enable rapid scanning and uptake of social contextual information; however, this pattern of visual attention was not pronounced in schizophrenia patients. In association with limited scanning and reduced visual attention to contextual information, schizophrenia patients' assessment of the mental state of characters embedded in social contexts was less accurate. CONCLUSION: In people with schizophrenia, inefficient integration of social contextual information in real-world situations may negatively affect the ability to infer mental and emotional states from facial expressions. |
Harold H. Greene Distance-from-target dynamics during visual search Journal Article In: Vision Research, vol. 48, no. 23-24, pp. 2476–2484, 2008. @article{Greene2008,Tseng, Y. C., & Li, C. S. (2004). Oculomotor correlates of context-guided learning in visual search. Perception & Psychophysics, 66, 1368-1378 noted that visual search with eye movements may be characterized by a search phase in which fixations do not move towards the target, followed by a phase in which fixations move steadily towards the target. They speculated that the phases are related to memory and recognition processes. Human visual search and Monte Carlo simulations are described towards an explanation. Distance-from-target dynamics were demonstrated to be sensitive to geometric constraints and therefore do not provide a solution to the question of memory in visual search. Finally, it is concluded that the specific distance-from-target dynamics noted by Tseng, Y. C., & Li, C. S. (2004). Oculomotor correlates of context-guided learning in visual search. Perception & Psychophysics, 66, 1368-1378 are parsimoniously explained by random walks that were initialized at the centre of their stimulus displays. |
Fred H. Hamker; Marc Zirnsak; Markus Lappe About the influence of post-saccadic mechanisms for visual stability on peri-saccadic compression of object location Journal Article In: Journal of Vision, vol. 8, no. 14, pp. 1–13, 2008. @article{Hamker2008,Peri-saccadic perception experiments have revealed a multitude of mislocalization phenomena. For instance, a briefly flashed stimulus is perceived closer to the saccade target, whereas a displacement of the saccade target goes usually unnoticeable. This latter saccadic suppression of displacement has been explained by a built-in characteristic of the perceptual system: the assumption that during a saccade, the environment remains stable. We explored whether the mislocalization of a briefly flashed stimulus toward the saccade target also grounds in the built-in assumption of a stable environment. If the mislocalization of a peri-saccadically flashed stimulus originates from a post-saccadic alignment process, an additional location marker at the position of the upcoming flash should counteract compression. Alternatively, compression might be the result of peri-saccadic attentional phenomena. In this case, mislocalization should occur even if the position of the flashed stimulus is marked. When subjects were asked about their perceived location, they mislocalized the stimulus toward the saccade target, even though they were fully aware of the correct stimulus location. Thus, our results suggest that the uncertainty about the location of a flashed stimulus is not inherently relevant for compression. |
Jesse A. Harris; Liina Pylkkänen; Brian McElree; Steven Frisson The cost of question concealment: Eye-tracking and MEG evidence Journal Article In: Brain and Language, vol. 107, no. 1, pp. 44–61, 2008. @article{Harris2008,Although natural language appears to be largely compositional, the meanings of certain expressions cannot be straightforwardly recovered from the meanings of their parts. This study examined the online processing of one such class of expressions: concealed questions, in which the meaning of a complex noun phrase (the proof of the theorem) shifts to a covert question (what the proof of the theorem is) when mandated by a sub-class of question-selecting verbs (e.g., guess). Previous behavioral and magnetoencephalographic (MEG) studies have reported a cost associated with converting an entity denotation to an event. Our study tested whether both types of meaning-shift affect the same computational resources by examining the effects elicited by concealed questions in eye-tracking and MEG. Experiment 1 found evidence from eye-movements that verbs requiring the concealed question interpretation require more processing time than verbs that do not support a shift in meaning. Experiment 2 localized the cost of the concealed question interpretation in the left posterior temporal region, an area distinct from that affected by complement coercion. Experiment 3 presented the critical verbs in isolation and found no posterior temporal effect, confirming that the effect of Experiment 2 reflected sentential, and not lexical-level, processing. |
Benjamin Y. Hayden; Sarah R. Heilbronner; Amrita C. Nair; Michael L. Platt Cognitive influences on risk-seeking by rhesus macaques Journal Article In: Judgment and Decision Making, vol. 3, no. 5, pp. 389–395, 2008. @article{Hayden2008,Humans and other animals are idiosyncratically sensitive to risk, either preferring or avoiding options having the same value but differing in uncertainty. Many explanations for risk sensitivity rely on the non-linear shape of a hypothesized utility curve. Because such models do not place any importance on uncertainty per se, utility curve-based accounts predict indifference between risky and riskless options that offer the same distribution of rewards. Here we show that monkeys strongly prefer uncertain gambles to alternating rewards with the same payoffs, demonstrating that uncertainty itself contributes to the appeal of risky options. Based on prior observations, we hypothesized that the appeal of the risky option is enhanced by the salience of the potential jackpot. To test this, we subtly manipulated payoffs in a second gambling task. We found that monkeys are more sensitive to small changes in the size of the large reward than to equivalent changes in the size of the small reward, indicating that they attend preferentially to the jackpots. Together, these results challenge utility curve-based accounts of risk sensitivity, and suggest that psychological factors, such as outcome salience and uncertainty itself, contribute to risky decision-making. |
Benjamin Y. Hayden; Amrita C. Nair; Allison N. McCoy; Michael L. Platt Posterior cingulate cortex mediates outcome-contingent allocation of behavior Journal Article In: Neuron, vol. 60, no. 1, pp. 19–25, 2008. @article{Hayden2008a,Adaptive decision making requires selecting an action and then monitoring its consequences to improve future decisions. The neuronal mechanisms supporting action evaluation and subsequent behavioral modification, however, remain poorly understood. To investigate the contribution of posterior cingulate cortex (CGp) to these processes, we recorded activity of single neurons in monkeys performing a gambling task in which the reward outcome of each choice strongly influenced subsequent choices. We found that CGp neurons signaled reward outcomes in a nonlinear fashion and that outcome-contingent modulations in firing rate persisted into subsequent trials. Moreover, firing rate on any one trial predicted switching to the alternative option on the next trial. Finally, microstimulation in CGp following risky choices promoted a preference reversal for the safe option on the following trial. Collectively, these results demonstrate that CGp directly contributes to the evaluative processes that support dynamic changes in decision making in volatile environments. |
Linus Holm; Johan Eriksson; Linus Andersson Looking as if you know: Systematic object inspection precedes object recognition Journal Article In: Journal of Vision, vol. 8, no. 4, pp. 1–7, 2008. @article{Holm2008,Sometimes we seem to look at the very object we are searching for, without consciously seeing it. How do we select object relevant information before we become aware of the object? We addressed this question in two recognition experiments involving pictures of fragmented objects. In Experiment 1, participants preferred to look at the target object rather than a control region 25 fixations prior to explicit recognition. Furthermore, participants inspected the target as if they had identified it around 9 fixations prior to explicit recognition. In Experiment 2, we investigated the influence of semantic knowledge in guiding object inspection prior to explicit recognition. Consistently, more specific knowledge about target identity made participants scan the fragmented stimulus more efficiently. For instance, non-target regions were rejected faster when participants knew the target object's name. Both experiments showed that participants were looking at the objects as if they knew them before they became aware of their identity. |
L. Elliot Hong; Kathleen A. Turano; Hugh B. O'Neill; Lei Hao; Ikwunga Wonodi; Robert P. McMahon; Amie Elliott; Gunvant K. Thaker Refining the predictive pursuit endophenotype in schizophrenia. Journal Article In: Biological Psychiatry, vol. 63, no. 5, pp. 458–464, 2008. @article{Hong2008,Background: To utilize fully a schizophrenia endophenotype in gene search and subsequent neurobiological studies, it is critical that the precise underlying physiologic deficit is identified. Abnormality in smooth pursuit eye movements is one of the endophenotypes of schizophrenia. The precise nature of the abnormality is unknown. Previous work has shown a reduced predictive pursuit response to a briefly masked (i.e., invisible) moving object in schizophrenia. However, the overt awareness of target removal can confound the measurement. Methods: This study employed a novel method that covertly stabilized the moving target image onto the fovea. The foveal stabilization was implemented after the target on a monitor had oscillated at least for one cycle and near the change of direction when the eye velocity momentarily reached zero. Thus, the subsequent pursuit eye movements were completely predictive and internally driven. Eye velocity during this foveally stabilized smooth pursuit was compared among schizophrenia patients (n = 45), their unaffected first-degree relatives (n = 42), and healthy comparison subjects (n = 22). Results: Schizophrenia patients and their unaffected relatives performed similarly and both had substantially reduced predictive pursuit acceleration and velocity under the foveally stabilized condition. Conclusions: These findings show that inability to maintain internal representation of the target motion or integration of such information into a predictive response may be the specific brain deficit indexed by the smooth pursuit endophenotype in schizophrenia. Similar performance between patients and unaffected relatives suggests that the refined predictive pursuit measure may index a less complex genetic origin of the eye-tracking deficits in schizophrenia families. |
Jörg Hoormann; Stephanie Jainta; Wolfgang Jaschinski The effect of calibration errors on the accuracy of the eye movement recordings Journal Article In: Journal of Eye Movement Research, vol. 1, no. 2, pp. 1–7, 2008. @article{Hoormann2008,For calibrating eye movement recordings, a regression between spatially defined calibration points and corresponding measured raw data is performed. Based on this regression, a confidence interval (CI) of the actually measured eye position can be calculated in order tonquantify the measurement error introduced by inaccurate calibration coefficients. For calculating this CI, a standard deviation (SD) - depending on the calibration quality and thendesign of the calibration procedure - is needed.nExamples of binocular recordings with separate monocular calibrations illustrate that the SD is almost independent of the number and spatial separation between the calibration points – even though the later was expected from theoretical simulation. Our simulations and recordings demonstrate that the SD depends critically on residuals at certain calibration points, thus robust regressions are suggested. |
Janet Hui-wen Hsiao; Garrison W. Cottrell Two fixations suffice in face recognition Journal Article In: Psychological Science, vol. 19, no. 10, pp. 998–1006, 2008. @article{Hsiao2008,It is well known that there exist preferred landing positions for eye fixations in visual word recogni- tion. However, the existence ofpreferred landing positions in face recognition is less well established. It is also un- known how many fixations are required to recognize a face. To investigate these questions, we recorded eye movements during face recognition. During an otherwise standard face-recognition task, subjects were allowed a variable number of fixations before the stimulus was masked.We found that optimal recognition performance is achieved with two fixations; performance does not improve with additional fixations. The distribution of the first fix- ation is just to the left ofthe center ofthe nose, and that of the second fixation is around the center ofthe nose. Thus, these appear to be the preferred landing positions for face recognition. Furthermore, the fixations made during face learning differ in location from those made during face recognition and are also more variable in duration; this suggests that different strategies are used for face learning and face recognition. |
Xu Huang; Jin Jing; Xiao-bing Zou; Meng-Long Wang; Xiu-Hong Li; Ai-Hua Lin Eye movements characteristics of Chinese dyslexic children in picture searching Journal Article In: Chinese Medical Journal, vol. 121, no. 17, pp. 1617–1621, 2008. @article{Huang2008,Background: Reading Chinese, a kind of ideogram, relies more on visual cognition. The visuospatial cognitive deficit of Chinese dyslexia is an interesting topic that has received much attention. The purpose of current research was to explore the visuopatial cognitive characteristics of Chinese dyslexic children by studying their eye movements via a picture searching test. Methods: According to the diagnostic criteria defined by ICD-10, twenty-eight dyslexic children (mean age (10.12±1.42) years) were enrolled from the Clinic of Children Behavioral Disorder in the third affiliated hospital of Sun Yat-sen University. And 28 normally reading children (mean age (10.06±1.29) years), 1:1 matched by age, sex, grade and family condition were chosen from an elementary school in Guangzhou as a control group. Four groups of pictures (cock, accident, canyon, meditate) from Picture Vocabulary Test were chosen as eye movement experiment targets. All the subjects carried out the picture searching task and their eye movement data were recorded by an Eyelink II High-Speed Eye Tracker. The duration time, average fixation duration, average saccade amplitude, fixation counts and saccade counts were compared between the two groups of children. Results: The dyslexic children had longer total fixation duration and average fixation duration (F=7.711, P <0.01; F=4.520, P <0.05), more fixation counts and saccade counts (F=7.498, P <0.01; F=11.040, P <0.01), and a smaller average saccade amplitude (F=29.743, P <0.01) compared with controls. But their performance in the picture vocabulary test was the same as those of the control group. The eye movement indexes were affected by the difficulty of the pictures and words, all eye movement indexes, except saccade amplitude, had a significant difference within groups (P <0.05). Conclusions: Chinese dyslexic children have abnormal eye movements in picture searching, applying slow fixations, more fixations and small and frequent saccades. Their abnormal eye movement mode reflects the poor ability and strategy of visual information processing. |
Mark Yates; John Friend; Danielle M. Ploetz The effect of phonological neighborhood density on eye movements during reading Journal Article In: Cognition, vol. 107, no. 2, pp. 685–692, 2008. @article{Yates2008,Recent research has indicated that phonological neighbors speed processing in a variety of isolated word recognition tasks. Nevertheless, as these tasks do not represent how we normally read, it is not clear if phonological neighborhood has an effect on the reading of sentences for meaning. In the research reported here, we evaluated whether phonological neighborhood density influences reading of target words embedded in sentences. The eye movement data clearly revealed that phonological neighborhood facilitated reading. This was evidenced by shorter fixations for words with large neighborhoods relative to words with small neighborhoods. These results are important in indicating that phonology is a crucial component of reading and that it affects early lexical processing. textcopyright 2007 Elsevier B.V. All rights reserved. |