All EyeLink Publications
All 12,000+ peer-reviewed EyeLink research publications up until 2023 (with some early 2024s) are listed below by year. You can search the publications library using keywords such as Visual Search, Smooth Pursuit, Parkinson’s, etc. You can also search for individual author names. Eye-tracking studies grouped by research area can be found on the solutions pages. If we missed any EyeLink eye-tracking papers, please email us!
2014 |
Michiel Elk; Michiel Elk The left inferior parietal lobe represents stored hand-postures for object use and action prediction Journal Article In: Frontiers in Psychology, vol. 5, pp. 333, 2014. @article{Elk2014, Action semantics enables us to plan actions with objects and to predict others' object-directed actions as well. Previous studies have suggested that action semantics are represented in a fronto-parietal action network that has also been implicated to play a role in action observation. In the present fMRI study it was investigated how activity within this network changes as a function of the predictability of an action involving multiple objects and requiring the use of action semantics. Participants performed an action prediction task in which they were required to anticipate the use of a centrally presented object that could be moved to an associated target object (e.g., hammer-nail). The availability of actor information (i.e., presenting a hand grasping the central object) and the number of possible target objects (i.e., 0, 1, or 2 target objects) were independently manipulated, resulting in different levels of predictability. It was found that making an action prediction based on actor information resulted in an increased activation in the extrastriate body area (EBA) and the fronto-parietal action observation network (AON). Predicting actions involving a target object resulted in increased activation in the bilateral IPL and frontal motor areas. Within the AON, activity in the left inferior parietal lobe (IPL) and the left premotor cortex (PMC) increased as a function of the level of action predictability. Together these findings suggest that the left IPL represents stored hand-postures that can be used for planning object-directed actions and for predicting other's actions as well. |
Veronica Whitford; Debra Titone The effects of reading comprehension and launch site on frequency-predictability interactions during paragraph reading Journal Article In: Quarterly Journal of Experimental Psychology, vol. 67, no. 6, pp. 1151–1165, 2014. @article{Whitford2014, We used eye movement measures of paragraph reading to examine whether word frequency and predictability interact during the earliest stages of lexical processing, with a specific focus on whether these effects are modulated by individual differences in reading comprehension or launch site (i.e., saccade length between the prior and currently fixated word–a proxy for the amount of parafoveal word processing). The joint impact of frequency and predictability on reading will elucidate whether these variables additively or multiplicatively affect the earliest stages of lexical access, which, in turn, has implications for computational models of eye movements during reading. Linear mixed effects models revealed additive effects during both early- and late-stage reading, where predictability effects were comparable for low- and high-frequency words. Moreover, less cautious readers (e.g., readers who engaged in skimming, scanning, mindless reading) demonstrated smaller frequency effects than more cautious readers. Taken together, our findings suggest that during extended reading, frequency and predictability exert additive influences on lexical and postlexical processing, and that individual differences in reading comprehension modulate sensitivity to the effects of word frequency. |
Andreas Widmann; Ralf Engbert; Erich Schroger Microsaccadic responses indicate fast categorization of sounds: A novel approach to study auditory cognition Journal Article In: Journal of Neuroscience, vol. 34, no. 33, pp. 11152–11158, 2014. @article{Widmann2014, The mental chronometry of the human brain's processing of sounds to be categorized as targets has intensively been studied in cognitive neuroscience. According to current theories, a series of successive stages consisting of the registration, identification, and categorization of the sound has to be completed before participants are able to report the sound as a target by button press after ∼300-500 ms. Here we use miniature eye movements as a tool to study the categorization of a sound as a target or nontarget, indicating that an initial categorization is present already after 80-100 ms. During visual fixation, the rate of microsaccades, the fastest components of miniature eye movements, is transiently modulated after auditory stimulation. In two experiments, we measured microsaccade rates in human participants in an auditory three-tone oddball paradigm (including rare nontarget sounds) and observed a difference in the microsaccade rates between targets and nontargets as early as 142 ms after sound onset. This finding was replicated in a third experiment with directed saccades measured in a paradigm in which tones had to be matched to score-like visual symbols. Considering the delays introduced by (motor) signal transmission and data analysis constraints, the brain must have differentiated target from nontarget sounds as fast as 80-100 ms after sound onset in both paradigms. We suggest that predictive information processing for expected input makes higher cognitive attributes, such as a sound's identity and category, available already during early sensory processing. The measurement of eye movements is thus a promising approach to investigate hearing. |
Emily Wiecek; Kameran Lashkari; Steven C. Dakin; Peter J. Bex Novel quantitative assessment of metamorphopsia in maculopathy Journal Article In: Investigative Ophthalmology & Visual Science, vol. 56, no. 1, pp. 494–504, 2014. @article{Wiecek2014, PURPOSE: Patients with macular disease often report experiencing metamorphopsia (visual distortion). Although typically measured with Amsler charts, more quantitative assessments of perceived distortion are desirable to effectively monitor the presence, progression, and remediation of visual impairment. METHODS: Participants with binocular (n = 33) and monocular (n = 50) maculopathy across seven disease groups, and control participants (n = 10) with no identifiable retinal disease completed a modified Amsler grid assessment (presented on a computer screen with eye tracking to ensure fixation compliance) and two novel assessments to measure metamorphopsia in the central 5° of visual field. A total of 81% (67/83) of participants completed a hyperacuity task where they aligned eight dots in the shape of a square, and 64% (32/50) of participants with monocular distortion completed a spatial alignment task using dichoptic stimuli. Ten controls completed all tasks. RESULTS: Horizontal and vertical distortion magnitudes were calculated for each of the three assessments. Distortion magnitudes were significantly higher in patients than controls in all assessments. There was no significant difference in magnitude of distortion across different macular diseases. There were no significant correlations between overall magnitude of distortion among any of the three measures and no significant correlations in localized measures of distortion. CONCLUSIONS: Three alternative quantifications of monocular spatial distortion in the central visual field generated uncorrelated estimates of visual distortion. It is therefore unlikely that metamorphopsia is caused solely by retinal displacement, but instead involves additional top-down information, knowledge about the scene, and perhaps, cortical reorganization. |
Eva Wiese; Agnieszka Wykowska; Hermann J. Muller In: PLoS ONE, vol. 9, no. 4, pp. e94529, 2014. @article{Wiese2014, For effective social interactions with other people, information about the physical environment must be integrated with information about the interaction partner. In order to achieve this, processing of social information is guided by two components: a bottom-up mechanism reflexively triggered by stimulus-related information in the social scene and a top- down mechanism activated by task-related context information. In the present study, we investigated whether these components interact during attentional orienting to gaze direction. In particular, we examined whether the spatial specificity of gaze cueing is modulated by expectations about the reliability of gaze behavior. Expectations were either induced by instruction or could be derived from experience with displayed gaze behavior. Spatially specific cueing effects were observed with highly predictive gaze cues, but also when participants merely believed that actually non-predictive cues were highly predictive. Conversely, cueing effects for the whole gazed-at hemifield were observed with non-predictive gaze cues, and spatially specific cueing effects were attenuated when actually predictive gaze cues were believed to be non-predictive. This pattern indicates that (i) information about cue predictivity gained from sampling gaze behavior across social episodes can be incorporated in the attentional orienting to social cues, and that (ii) beliefs about gaze behavior modulate attentional orienting to gaze direction even when they contradict information available from social episodes. |
Heather Winskel; Manuel Perea Can parafoveal-on-foveal effects be obtained when reading an unspaced alphasyllabic script (Thai)? Journal Article In: Writing Systems Research, vol. 6, no. 1, pp. 94–104, 2014. @article{Winskel2014, One controversial question in the field of eye movements and reading is whether there is evidence of parafoveal-on-foveal effects. This is an important issue because some models of eye movements in reading make quite different predictions in this respect (e.g., E-Z Reader vs. SWIFT models). The aim of the current study was to investigate if parafoveal-on-foveal effects occur when reading Thai, an unspaced, alphasyllabic orthography. Word frequency (high and low) of the word to the right of the currently fixated word was manipulated to examine if it would influence processing of the fixated word. Thirty-six participants read single sentences while having their eye movements monitored. There was no evidence of the effect of word frequency of the parafoveal word on fixation duration measures of the foveal word, as assessed by p(H0|D) values - except for a marginal effect in the skipping rates. Thus, the present data are in line with previous studies using spaced Indo-European languages which have found small/null results for parafoveal effects of word frequency during one-line sentence reading. © 2013 Taylor & Francis. |
Heather Winskel; Khazriyati Salehudding Morphological parafoveal preview benefit effects when reading derived words in Malay Journal Article In: Kajian Malaysia, vol. 32, no. 2, pp. 23–40, 2014. @article{Winskel2014a, Eye-movement tracking is a method that is used to study reading across different languages and is increasingly being employed. Eye movements provide a window into the underlying cognitive processes and mechanisms while a person is reading (Rayner, 1998). The majority of research investigating eye movements during reading has been conducted on European languages such as English and German; relatively little work has been conducted on other writing systems such as Malay. Malay offers an interesting opportunity to investigate early morphological processing because Malay has a rich derivational morphology that is more structurally and semantically transparent than English. The current study investigates whether the morphological constituents of affixed words (prefixed and suffixed) in Malay influence early word processing during reading using the boundary paradigm (Rayner, 1975). The boundary paradigm involves the positioning of a preview word stimulus in place of the target word so that when the eyes move towards the preview word, they cross an invisible boundary that triggers a change from the preview word to the target word. Two commonly used affixes were used: a prefix pe- and a suffix -an, which both convert a verb into a nominal (e.g. lakon, "to act", with the prefix pe- becomes pelakon, "actor"; and makan, "to eat", with the suffix -an becomes makanan, "food"). Thirty participants read 72 single sentences that were identical in length (having the same number of letters) and contained affixed and pseudo-affixed words. Parafoveal previews consisted of identical affixed and control conditions. The dependent measures were first fixation duration and gaze duration. The results revealed a significant preview benefit for the identical condition compared with the affixed and control conditions and for the affixed condition compared with the control condition. This effect was not influenced by word type; hence, there was no evidence of morphological pre-processing. In conclusion, the results from the current study indicate that although Malay is a morphologically rich language with a relatively transparent orthography, readers do not necessarily utilise early morphological processes. The results are discussed in terms of language and orthography-specific differences in early morphological processing. |
Siavash Vaziri; Eric T. Carlson; Zhihong Wang; Charles E. Connor A channel for 3D environmental shape in anterior inferotemporal cortex Journal Article In: Neuron, vol. 84, no. 1, pp. 55–62, 2014. @article{Vaziri2014, Inferotemporal cortex (IT) has long been studied as asingle pathway dedicated to object vision, but connectivity analysis reveals anatomically distinct channels, through ventral superior temporal sulcus (STSv) and dorsal/ventral inferotemporal gyrus (TEd, TEv). Here, we report a major functional distinction between channels. We studied individual IT neurons in monkeys viewing stereoscopic 3D images projected on a large screen. We used adaptive stimuli to explore neural tuning for 3D abstract shapes ranging in scale and topology from small, closed, bounded objects to large, open, unbounded environments (landscape-like surfaces and cave-like interiors). In STSv, most neurons were more responsive to objects, as expected. In TEd, surprisingly, most neurons were more responsive to 3D environmental shape. Previous studies have localized environmental information to posterior cortical modules. Our results show it is also channeled through anterior IT, where extensive cross-connections between STSv and TEd could integrate object and environmental shape information. |
Aaron Veldre; Sally Andrews Lexical quality and eye movements: Individual differences in the perceptual span of skilled adult readers Journal Article In: Quarterly Journal of Experimental Psychology, vol. 67, no. 4, pp. 703–727, 2014. @article{Veldre2014, Two experiments used the gaze-contingent moving-window paradigm to investigate whether reading comprehension and spelling ability modulate the perceptual span of skilled adult readers during sentence reading. Highly proficient reading and spelling were both associated with increased use information to the right of fixation, but did not systematically modulate the extraction of information to the left of fixation. Individuals who were high in both reading and spelling ability showed the greatest benefit from window sizes larger than 11 characters, primarily because of increases in forward saccade length. They were also significantly more disrupted by being denied close parafoveal information than those poor in reading and/or spelling. These results suggest that, in addition to supporting rapid lexical retrieval of fixated words, the high quality lexical representations indexed by the combination of high reading and spelling ability support efficient processing of parafoveal information and effective saccadic targeting. |
Boris M. Velichkovsky; Mikhail A. Rumyantsev; Mikhail A. Morozov New solution to the Midas Touch Problem: Identification of visual commands via extraction of focal fixations Journal Article In: Procedia Computer Science, vol. 39, pp. 75–82, 2014. @article{Velichkovsky2014, Reliable identification of intentional visual commands is a major problem in the development of eye-movements based user interfaces. This work suggests that the presence of focal visual fixations is indicative of visual commands. Two experiments are described which assessed the effectiveness of this approach in a simple gaze-control interface. Identification accuracy was shown to match that of the commonly used dwell time method. Using focal fixations led to less visual fatigue and higher speed of work. Perspectives of using focal fixations for identification of visual commands in various kinds of eye-movements based interfaces are discussed. |
Dustin Venini; Roger W. Remington; Gernot Horstmann; Stefanie I. Becker Centre-of-gravity fixations in visual search: When looking at nothing helps to find something Journal Article In: Journal of Ophthalmology, vol. 2014, pp. 9–12, 2014. @article{Venini2014, In visual search, some fixations are made between stimuli on empty regions, commonly referred to as "centre-of-gravity" fixations (henceforth: COG fixations). Previous studies have shown that observers with task expertise show more COG fixations than novices. This led to the view that COG fixations reflect simultaneous encoding of multiple stimuli, allowing more efficient processing of task-related items. The present study tested whether COG fixations also aid performance in visual search tasks with unfamiliar and abstract stimuli. Moreover, to provide evidence for the multiple-item processing view, we analysed the effects of COG fixations on the number and dwell times of stimulus fixations. The results showed that (1) search efficiency increased with increasing COG fixations even in search for unfamiliar stimuli and in the absence of special higher-order skills, (2) COG fixations reliably reduced the number of stimulus fixations and their dwell times, indicating processing of multiple distractors, and (3) the proportion of COG fixations was dynamically adapted to potential information gain of COG locations. A second experiment showed that COG fixations are diminished when stimulus positions unpredictably vary across trials. Together, the results support the multiple-item processing view, which has important implications for current theories of visual search. |
Frederick Verbruggen; Tobias Stevens; Christopher D. Chambers Proactive and reactive stopping when distracted: An attentional account Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 40, no. 4, pp. 1295–1300, 2014. @article{Verbruggen2014, Performance in response inhibition paradigms is typically attributed to inhibitory control. Here we examined the idea that stopping may largely depend on the outcome of a sensory detection process. Subjects performed a speeded go task, but they were instructed to withhold their response when a visual stop signal was presented. The stop signal could occur in the center of the screen or in the periphery. On half of the trials, perceptual distractors were presented throughout the trial. We found that these perceptual distractors impaired stopping, especially when stop signals could occur in the periphery. Furthermore, the effect of the distractors on going was smallest in the central stop-signal condition, medium in a condition in which no signals could occur, and largest in the condition in which stop signals could occur in the periphery. The results show that an important component of stopping is finding a balance between ignoring irrelevant information in the environment and monitoring for the occurrence of occasional stop signals. These findings highlight the importance of sensory detection processes when stopping and could shed new light on a range of phenomena and findings in the response inhibition literature. |
Karl Verfaillie; S. Huysegems; Peter De Graef; Goedele Van Belle Impaired holistic and analytic face processing in congenital prosopagnosia: Evidence from the eye-contingent mask/window paradigm Journal Article In: Visual Cognition, vol. 22, no. 3, pp. 503–521, 2014. @article{Verfaillie2014, There is abundant evidence that face recognition, in comparison to the recognition of other objects, is based on holistic processing rather than analytic processing. One line of research that provides evidence for this hypothesis is based on the study of people who experience pronounced difficulties in visually identifying conspecifics on the basis of their face. Earlier, we developed a behavioural paradigm to directly test analytic vs. holistic face processing. In comparison to a to be remembered reference face stimulus, one of two test stimuli was either presented in full view, with an eye-contingently moving window (only showing the fixated face feature, and therefore only affording analytic processing), or with an eye-contingently moving mask or scotoma (masking the fixated face feature, but still allowing holistic processing). In the present study we use this paradigm (that we used earlier in acquired prosopagnosia) to study face perception in congenital prosopagnosia (people having difficulties recognizing faces from birth on, without demonstrable brain damage). We observe both holistic and analytic face processing deficits in people with congenital prosopagnosia. Implications for a better understanding, both of congenital prosopagnosia and of normal face perception, are discussed. There is abundant evidence that face recognition, in comparison to the recognition of other objects, is based on holistic processing rather than analytic processing. One line of research that provides evidence for this hypothesis is based on the study of people who experience pronounced difficulties in visually identifying conspecifics on the basis of their face. Earlier, we developed a behavioural paradigm to directly test analytic vs. holistic face processing. In comparison to a to be remembered reference face stimulus, one of two test stimuli was either presented in full view, with an eye-contingently moving window (only showing the fixated face feature, and therefore only affording analytic processing), or with an eye-contingently moving mask or scotoma (masking the fixated face feature, but still allowing holistic processing). In the present study we use this paradigm (that we used earlier in acquired prosopagnosia) to study face perception in congenital prosopagnosia (people having difficulties recognizing faces from birth on, without demonstrable brain damage). We observe both holistic and analytic face processing deficits in people with congenital prosopagnosia. Implications for a better understanding, both of congenital prosopagnosia and of normal face perception, are discussed. |
Cyril Vienne; Laurent Sorin; Laurent Blondé; Quan Huynh-Thu; Pascal Mamassian Effect of the accommodation-vergence conflict on vergence eye movements Journal Article In: Vision Research, vol. 100, pp. 124–133, 2014. @article{Vienne2014, With the broader use of stereoscopic displays, a flurry of research activity about the accommodation- vergence conflict has emerged to highlight the implications for the human visual system. In stereoscopic displays, the introduction of binocular disparities requires the eyes to make vergence movements. In this study, we examined vergence dynamics with regard to the conflict between the stimulus-to- accommodation and the stimulus-to-vergence. In a first experiment, we evaluated the immediate effect of the conflict on vergence responses by presenting stimuli with conflicting disparity and focus on a stereoscopic display (i.e. increasing the stereoscopic demand) or by presenting stimuli with matched disparity and focus using an arrangement of displays and a beam splitter (i.e. focus and disparity specifying the same locations). We found that the dynamics of vergence responses were slower overall in the first case due to the conflict between accommodation and vergence. In a second experiment, we examined the effect of a prolonged exposure to the accommodation-vergence conflict on vergence responses, in which participants judged whether an oscillating depth pattern was in front or behind the fixation plane. An increase in peak velocity was observed, thereby suggesting that the vergence system has adapted to the stereoscopic demand. A slight increase in vergence latency was also observed, thus indicating a small decline of vergence performance. These findings offer a better understanding and document how the vergence system behaves in stereoscopic displays. We describe what stimuli in stereo-movies might produce these oculomotor effects, and discuss potential applications perspectives. |
B. Vintch; Justin L. Gardner Cortical correlates of human motion perception biases Journal Article In: Journal of Neuroscience, vol. 34, no. 7, pp. 2592–2604, 2014. @article{Vintch2014, Human sensory perception is not a faithful reproduction of the sensory environment. For example, at low contrast, objects appear to move slower and flicker faster than veridical. Although these biases have been observed robustly, their neural underpinning is unknown, thus suggesting a possible disconnect of the well established link between motion perception and cortical responses. We used functional imaging to examine the encoding of speed in the human cortex at the scale of neuronal populations and asked where and how these biases are encoded. Decoding, voxel population, and forward-encoding analyses revealed biases toward slow speeds and high temporal frequencies at low contrast in the earliest visual cortical regions, matching perception. These findings thus offer a resolution to the disconnect between cortical responses and motion perception in humans. Moreover, biases in speed perception are considered a leading example of Bayesian inference because they can be interpreted as a prior for slow speeds. Therefore, our data suggest that perceptual priors of this sort can be encoded by neural populations in the same early cortical areas that provide sensory evidence. |
Chien-Chih Tseng; Ching-Hui Chen; Hsuan-Chih Chen; Yao-Ting Sung; Kuo-En Chang Verification of Dual Factors theory with eye movements during a matchstick arithmetic insight problem Journal Article In: Thinking Skills and Creativity, vol. 13, pp. 129–140, 2014. @article{Tseng2014, Representational Change Theory claims that participants form inappropriate representations at the beginning of the insight problem solving process and that these initial representations must be transformed to discover the solution (Knoblich, Ohlsson, Haider, & Rhenius, 1999; Knoblich, Ohlsson, & Raney, 2001; Ohlsson, 1992). The theory also claims that all participants are trapped by inappropriate representations, regardless of the result, but it is easier for successful participants to transform their initial representations. However, the transformation of representations is not the only critical factor. This study investigates the hypothesis that the process of fixedness averting plays an important role in insight problem solving and is helpful for representational change. To verify the influence of fixedness averting on representational change processes, matchstick arithmetic problems were employed as an experimental model. In experiment 1, insight problem solving results could be predicted within the first third of the duration of the task. The gaze duration in the fixation region of successful participants was shorter than the gaze duration of unsuccessful participants. In experiment 2, participants' foci of attention were experimentally manipulated by presenting different animated diagrams to guide their attention. We found that the rate of correct responses was significantly reduced when participants' attention was guided to the fixation region. Representational Change Theory declares that changing inappropriate initial representations is necessary for solving insight problems. The present study demonstrates that in addition to representational change, fixedness averting is also crucial to problem solving. |
Lin-Yuan Tseng; Philip Tseng; Wei-Kuang Liang; Daisy L. Hung; Ovid J. L. Tzeng; Neil G. Muggleton; Chi-Hung Juan The role of superior temporal sulcus in the control of irrelevant emotional face processing: A transcranial direct current stimulation study Journal Article In: Neuropsychologia, vol. 64, pp. 124–133, 2014. @article{Tseng2014a, Emotional faces are often salient cues of threats or other important contexts, and may therefore have a large effect on cognitive processes of the visual environment. Indeed, many behavioral studies have demonstrated that emotional information can modulate visual attention and eye movements. The aim of the present study was to investigate (1) how irrelevant emotional face distractors affect saccadic behaviors and (2) whether such emotional effects reflect a specific neural mechanism or merely biased selective attention. We combined a visual search paradigm that incorporated manipulation of different types of distractor (fearful faces or scrambled faces) and delivered anodal transcranial direct current stimulation (tDCS) over the superior temporal sulcus and the frontal eye field to investigate the functional roles of these areas in processing facial expressions and eye movements. Our behavioral data suggest that irrelevant emotional distractors can modulate saccadic behaviors. The tDCS results showed that while rFEF played a more general role in controlling saccadic behavior, rSTS is mainly involved in facial expression processing. Furthermore, rSTS played a critical role in processing facial expressions even when such expressions were not relevant to the task goal, implying that facial expressions and processing may be automatic irrespective of the task goal. |
Yuan-Chi Tseng; Joshua I. Glaser; Eamon Caddigan; Alejandro Lleras Modeling the effect of selection history on pop-out visual search Journal Article In: PLoS ONE, vol. 9, no. 3, pp. e89996, 2014. @article{Tseng2014b, While attentional effects in visual selection tasks have traditionally been assigned "top-down" or "bottom-up" origins, more recently it has been proposed that there are three major factors affecting visual selection: (1) physical salience, (2) current goals and (3) selection history. Here, we look further into selection history by investigating Priming of Pop-out (POP) and the Distractor Preview Effect (DPE), two inter-trial effects that demonstrate the influence of recent history on visual search performance. Using the Ratcliff diffusion model, we model observed saccadic selections from an oddball search experiment that included a mix of both POP and DPE conditions. We find that the Ratcliff diffusion model can effectively model the manner in which selection history affects current attentional control in visual inter-trial effects. The model evidence shows that bias regarding the current trial's most likely target color is the most critical parameter underlying the effect of selection history. Our results are consistent with the view that the 3-item color-oddball task used for POP and DPE experiments is best understood as an attentional decision making task. |
Yusuke Uchida; Nobuaki Mizuguchi; Masaaki Honda; Kazuyuki Kanosue Prediction of shot success for basketball free throws: Visual search strategy Journal Article In: European Journal of Sport Science, vol. 14, no. 5, pp. 426–432, 2014. @article{Uchida2014, Abstract In ball games, players have to pay close attention to visual information in order to predict the movements of both the opponents and the ball. Previous studies have indicated that players primarily utilise cues concerning the ball and opponents' body motion. The information acquired must be effective for observing players to select the subsequent action. The present study evaluated the effects of changes in the video replay speed on the spatial visual search strategy and ability to predict free throw success. We compared eye movements made while observing a basketball free throw by novices and experienced basketball players. Correct response rates were close to chance (50%) at all video speeds for the novices. The correct response rate of experienced players was significantly above chance (and significantly above that of the novices) at the normal speed, but was not different from chance at both slow and fast speeds. Experienced players gazed more on the lower part of the player's body when viewing a normal speed video than the novices. The players likely detected critical visual information to predict shot success by properly moving their gaze according to the shooter's movements. This pattern did not change when the video speed was decreased, but changed when it was increased. These findings suggest that temporal information is important for predicting action outcomes and that such outcomes are sensitive to video speed. |
Hiroshi Ueda; Kohske Takahashi; Katsumi Watanabe Influence of removal of invisible fixation on the saccadic and manual gap effect Journal Article In: Experimental Brain Research, vol. 232, no. 1, pp. 329–336, 2014. @article{Ueda2014, Saccadic and manual reactions to a peripherally presented target are facilitated by removing a central fixation stimulus shortly before a target onset (the gap effect). The present study examined the effects of removal of a visible and invisible fixation point on the saccadic gap effect and the manual gap effect. Participants were required to fixate a central fixation point and respond to a peripherally presented target as quickly and accurately as possible by making a saccade (Experiment 1) or pressing a corresponding key (Experiment 2). The fixation point was dichoptically presented, and visibility was manipulated by using binocular rivalry and continuous flash suppression technique. In both saccade and key-press tasks, removing the visible fixation strongly quickened the responses. Furthermore, the invisible fixation, which remained on the display but suppressed, significantly delayed the saccadic response. Contrarily, the invisible fixation had no effect on the manual task. These results indicate that partially different processes mediate the saccadic gap effect and the manual gap effect. In particular, unconscious processes might modulate an oculomotor-specific component of the saccadic gap effect, presumably via subcortical mechanisms. |
Hiroshi Ueda; Kohske Takahashi; Katsumi Watanabe Effects of direct and averted gaze on the subsequent saccadic response Journal Article In: Attention, Perception, and Psychophysics, vol. 76, no. 4, pp. 1085–1092, 2014. @article{Ueda2014a, The saccadic latency to visual targets is susceptible to the properties of the currently fixated objects. For example, the disappearance of a fixation stimulus prior to presentation of a peripheral target shortens saccadic latencies (the gap effect). In the present study, we investigated the influences of a social signal from a facial fixation stimulus (i.e., gaze direction) on subsequent saccadic responses in the gap paradigm. In Experiment 1, a cartoon face with a direct or averted gaze was used as a fixation stimulus. The pupils of the face were unchanged (overlap), disappeared (gap), or were translated vertically to make or break eye contact (gaze shift). Participants were required to make a saccade toward a target to the left or the right of the fixation stimulus as quickly as possible. The results showed that the gaze direction influenced saccadic latencies only in the gaze shift condition, but not in the gap or overlap condition; the direct-to-averted gaze shift (i.e., breaking eye contact) yielded shorter saccadic latencies than did the averted-to-direct gaze shift (i.e., making eye contact). Further experiments revealed that this effect was eye contact specific (Exp. 2) and that the appearance of an eye gaze immediately before the saccade initiation also influenced the saccadic latency, depending on the gaze direction (Exp. 3). These results suggest that the latency of target-elicited saccades can be modulated not only by physical changes of the fixation stimulus, as has been seen in the conventional gap effect, but also by a social signal from the attended fixation stimulus. |
Avinash R. Vaidya; Chenshuo Jin; Lesley K. Fellows Eye spy: The predictive value of fixation patterns in detecting subtle and extreme emotions from faces Journal Article In: Cognition, vol. 133, no. 2, pp. 443–456, 2014. @article{Vaidya2014, Successful social interaction requires recognizing subtle changes in the mental states of others. Deficits in emotion recognition are found in several neurological and psychiatric illnesses, and are often marked by disturbances in gaze patterns to faces, typically interpreted as a failure to fixate on emotionally informative facial features. However, there has been very little research on how fixations inform emotion recognition in healthy people. Here, we asked whether fixations predicted detection of subtle and extreme emotions in faces. We used a simple model to predict emotion detection scores from participants' fixation patterns. The best fit of this model heavily weighted fixations to the eyes in detecting subtle fear, disgust and surprise, with less weight, or zero weight, given to mouth and nose fixations. However, this model could not successfully predict detection of subtle happiness, or extreme emotional expressions, with the exception of fear. These findings argue that detection of most subtle emotions is best served by fixations to the eyes, with some contribution from nose and mouth fixations. In contrast, detection of extreme emotions and subtle happiness appeared to be less dependent on fixation patterns. The results offer a new perspective on some puzzling dissociations in the neuropsychological literature, and a novel analytic approach for the study of eye gaze in social or emotional settings. |
Chin-An Wang; Douglas P. Munoz Modulation of stimulus contrast on the human pupil orienting response Journal Article In: European Journal of Neuroscience, vol. 40, no. 5, pp. 2822–2832, 2014. @article{Wang2014, The sudden appearance of a novel stimulus initiates a series of responses to orient the body for appropriate actions, including not only shifts of gaze and attention, but also transient pupil dilation. Modulation of pupil dynamics by stimulus properties is less understood, although its effects on other components of orienting have been extensively explored. Microstimulation of the superior colliculus evoked transient pupil dilation, and the initial component of pupil dilation evoked by microstimulation was similar to that elicited by the presentation of salient sensory stimuli, suggesting a coordinated role of the superior colliculus on this behavior, although evidence in humans is yet to be established. To examine pupil orienting responses in humans, we presented visual stimuli while participants fixated on a central visual spot. Transient pupil dilation in humans was elicited after presentation of a visual stimulus in the periphery. The evoked pupil responses were modulated systematically by stimulus contrast, with faster and larger pupil responses triggered by higher contrast stimuli. The pupil response onset latencies for high contrast stimuli were similar to those produced by the light reflex and significantly faster than the darkness reflex, suggesting that the initial component of pupil dilation is probably mediated by inhibition of the parasympathetic pathway. The contrast modulation was pronounced under different levels of baseline pupil size. Together, our results demonstrate visual contrast modulation on the orienting pupil response in humans. |
H. X. Wang; Elisha P. Merriam; Jeremy Freeman; David J. Heeger Motion direction biases and decoding in human visual cortex Journal Article In: Journal of Neuroscience, vol. 34, no. 37, pp. 12601–12615, 2014. @article{Wang2014h, Functional magnetic resonance imaging (fMRI) studies have relied on multivariate analysis methods to decode visual motion direction from measurements of cortical activity. Above-chance decoding has been commonly used to infer the motion-selective response properties of the underlying neural populations. Moreover, patterns of reliable response biases across voxels that underlie decoding have been interpreted to reflect maps of functional architecture. Using fMRI, we identified a direction-selective response bias in human visual cortex that: (1) predicted motion-decoding accuracy; (2) depended on the shape of the stimulus aperture rather than the absolute direction of motion, such that response amplitudes gradually decreased with distance from the stimulus aperture edge corresponding to motion origin; and 3) was present in V1, V2, V3, but not evident in MT+, explaining the higher motion-decoding accuracies reported previously in early visual cortex. These results demonstrate that fMRI-based motion decoding has little or no dependence on the underlying functional organization of motion selectivity. |
Hsiao-shen Wang; Yi-Ting Chen; Chih-Hung Lin The learning benefits of using eye trackers to enhance the geospatial abilities of elementary school students Journal Article In: British Journal of Educational Technology, vol. 45, no. 2, pp. 340–355, 2014. @article{Wang2014c, In this study, we examined the spatial abilities of students using eye-movement tracking devices to identify and analyze their characteristics. For this research, 12 students aged 11–12 years participated as novices and 4 mathematics students participated as experts. A comparison of the visual-spatial abilities of each group showed key factors of superior spatial ability, and a spatial ability instructional strategy was developed. After training, the same spatial ability test was conducted again, and eye-tracking records were used to compare the participants' line-of-sight and answer rate results with those of the previous test. Specific references and recommendations are provided for spatial ability training education and assessment. |
Jingxin Wang; Jing Tian; Weijin Han; Simon P. Liversedge; Kevin B. Paterson Inhibitory stroke neighbour priming in character recognition and reading in Chinese Journal Article In: Quarterly Journal of Experimental Psychology, vol. 67, no. 11, pp. 2149–2171, 2014. @article{Wang2014d, In alphabetic languages, prior exposure to a target word's orthographic neighbour influences word recognition in masked priming experiments and the process of word identification that occurs during normal reading. We investigated whether similar neighbour priming effects are observed in Chinese in 4 masked priming experiments (employing a forward mask and 33-ms, 50-ms, and 67-ms prime durations) and in an experiment that measured eye movements while reading. In these experiments, the stroke neighbour of a Chinese character was defined as any character that differed by the addition, deletion, or substitution of one or two strokes. Prime characters were either stroke neighbours or stroke non-neighbours of the target character, and each prime character had either a higher or a lower frequency of occurrence in the language than its corresponding target character. Frequency effects were observed in all experiments, demonstrating that the manipulation of character frequency was successful. In addition, a robust inhibitory priming effect was observed in response times for target characters in the masked priming experiments and in eye fixation durations for target characters in the reading experiment. This stroke neighbour priming was not modulated by the relative frequency of the prime and target characters. The present findings therefore provide a novel demonstration that inhibitory neighbour priming shown previously for alphabetic languages is also observed for nonalphabetic languages, and that neighbour priming (based on stroke overlap) occurs at the level of the character in Chinese. |
Lihui Wang; Yunyan Duan; Jan Theeuwes; Xiaolin Zhou Reward breaks through the inhibitory region around attentional focus Journal Article In: Journal of Vision, vol. 14, no. 12, pp. 2–2, 2014. @article{Wang2014e, It is well known that directing attention to a location in space enhances the processing efficiency of stimuli presented at that location. Research has also shown that around this area of enhanced processing, there is an inhibitory region within which processing of information is suppressed. In this study, we investigated whether a reward-associated stimulus can break through the inhibitory surround. A distractor that was previously associated with high or low reward was presented near the target with a variable distance between them. For low-reward distractors, only the distractor very close to the target caused interference to target processing; for high-reward distractors, both near and relatively far distractors caused interference, demonstrating that task-irrelevant reward-associated stimuli can capture attention even when presented within the inhibitory surround. |
Shuo Wang; Juan Xu; Ming Jiang; Qi Zhao; Rene Hurlemann; Ralph Adolphs Autism spectrum disorder, but not amygdala lesions, impairs social attention in visual search Journal Article In: Neuropsychologia, vol. 63, pp. 259–274, 2014. @article{Wang2014f, People with autism spectrum disorders (ASD) have pervasive impairments in social interactions, a diagnostic component that may have its roots in atypical social motivation and attention. One of the brain structures implicated in the social abnormalities seen in ASD is the amygdala. To further characterize the impairment of people with ASD in social attention, and to explore the possible role of the amygdala, we employed a series of visual search tasks with both social (faces and people with different postures, emotions, ages, and genders) and non-social stimuli (e.g., electronics, food, and utensils). We first conducted trial-wise analyses of fixation properties and elucidated visual search mechanisms. We found that an attentional mechanism of initial orientation could explain the detection advantage of non-social targets. We then zoomed into fixation-wise analyses. We defined target-relevant effects as the difference in the percentage of fixations that fell on target-congruent vs. target-incongruent items in the array. In Experiment 1, we tested 8 high-functioning adults with ASD, 3 adults with focal bilateral amygdala lesions, and 19 controls. Controls rapidly oriented to target-congruent items and showed a strong and sustained preference for fixating them. Strikingly, people with ASD oriented significantly less and more slowly to target-congruent items, an attentional deficit especially with social targets. By contrast, patients with amygdala lesions performed indistinguishably from controls. In Experiment 2, we recruited a different sample of 13 people with ASD and 8 healthy controls, and tested them on the same search arrays but with all array items equalized for low-level saliency. The results replicated those of Experiment 1. In Experiment 3, we recruited 13 people with ASD, 8 healthy controls, 3 amygdala lesion patients and another group of 11 controls and tested them on a simpler array. Here our group effect for ASD strongly diminished and all four subject groups showed similar target-relevant effects. These findings argue for an attentional deficit in ASD that is disproportionate for social stimuli, cannot be explained by low-level visual properties of the stimuli, and is more severe with high-load top-down task demands. Furthermore, this deficit appears to be independent of the amygdala, and not evident from general social bias independent of the target-directed search. |
David E. Warren; Melissa C. Duff Not so fast: Hippocampal amnesia slows word learning despite successful fast mapping Journal Article In: Hippocampus, vol. 24, no. 8, pp. 920–933, 2014. @article{Warren2014, The human hippocampus is widely believed to be necessary for the rapid acquisition of new declarative relational memories. However, processes supporting on-line inferential word use ("fast mapping") may also exercise a dissociable learning mechanism and permit rapid word learning without the hippocampus (Sharon et al. (2011) Proc Natl Acad Sci USA 108:1146-1151). We investigated fast mapping in severely amnesic patients with hippocampal damage (N = 4), mildly amnesic patients (N = 6), and healthy comparison participants (N = 10) using on-line measures (eye movements) that reflected ongoing processing. All participants studied unique word-picture associations in two encoding conditions. In the explicit-encoding condition, uncommon items were paired with their names (e.g., "This is a numbat."). In the fast mapping study condition, participants heard an instruction using a novel word (e.g., "Click on the numbat.") while two items were presented (an uncommon target such as a numbat, and a common distracter such as a dog). All groups performed fast mapping well at study, and on-line eye movement measures did not reveal group differences. However, while comparison participants showed robust word learning irrespective of encoding condition, severely amnesic patients showed no evidence of learning after fast mapping or explicit encoding on any behavioral or eye-movement measure. Mildly amnesic patients showed some learning, but performance was unaffected by encoding condition. The findings are consistent with the following propositions: the hippocampus is not essential for on-line fast mapping of novel words; but is necessary for the rapid learning of arbitrary relational information irrespective of encoding conditions. |
Matthew David Weaver; Davide Paoletti; Wieske Zoest The impact of predictive cues and visual working memory on dynamic oculomotor selection Journal Article In: Journal of Vision, vol. 14, no. 3, pp. 1–15, 2014. @article{Weaver2014, Strategic use of advanced information about search display properties can benefit covert attentional selection. However, little work has investigated this benefit on overt selection. The present study examined how cued information impacts oculomotor selection over time and the role played by individual differences in visual working memory (VWM) capacity in utilizing such cues. Participants searched for a specific orientation target in a saccade localization search task. Prior to each trial, additional information regarding secondary display features (color singleton identity) was either provided by a word cue or not. The cue increased accuracy performance from the earliest saccadic responses. VWM capacity was measured via a change-detection task and results showed that individuals' VWM capacity scores were associated with cue impact, whereby participants with higher capacity derived an increased cue performance benefit. These findings suggest that strategic use of cue information to select and reject salient singletons can develop very early following display presentation and is related to an individual's VWM capacity. This research indicates that stimulus- driven and goal-directed processes are not simply additive in oculomotor selection, but instead exhibit a distinct and dynamic profile of interaction. |
Hanna Weichselbaum; Isabella Fuchs; Ulrich Ansorge Oculomotor capture by supraliminal and subliminal onset singletons: The role of contrast polarity Journal Article In: Vision Research, vol. 100, pp. 1–7, 2014. @article{Weichselbaum2014, According to a top-down explanation of subliminal oculomotor capture, only subliminal distractors with a contrast polarity matching that of the searched-for targets should capture attention. For instance, when looking for white targets only subliminal white but not black distractors should capture attention. In contrast, according to a bottom-up explanation of such capture effects, subliminal distractors with a contrast polarity different to that of the searched-for targets should also capture attention. For instance, even when looking for white targets, subliminal black distractors should capture attention. Here, we used subliminal singleton-onset distractors in the same vertical hemifield as the target versus singleton-onset distractors in the opposite vertical field to the target, and tested whether oculomotor capture by these distractors depended on a match between the searched-for target contrasts and the distractor contrasts, by measuring saccade latency, saccade trajectory deviation, and saccade endpoint deviation. We found evidence for oculomotor capture: subliminal distractors in the opposite field delayed saccade execution towards the target. This delay was found in comparison to subliminal distractors in the same hemifield as the target. In line with a bottom-up explanation, this delay was independent of the similarity between the distractor contrast polarity and the searched-for target contrast polarity. Together with the subliminality of the distractors, the experiment confirmed bottom-up oculomotor capture by subliminal singleton-onsets. |
Katharina Weiß; Werner X. Schneider; Arvid Herwig Associating peripheral and foveal visual input across saccades: A default mode of the human visual system? Journal Article In: Journal of Vision, vol. 14, no. 11, pp. 1–15, 2014. @article{Weiss2014, Spatial processing resolution of a particular object in the visual field can differ considerably due to eye movements. The same object will be represented with high acuity in the fovea but only coarsely in periphery. Herwig and Schneider (in press) proposed that the visual system counteracts such resolution differences by predicting, based on previous experience, how foveal objects will look in the periphery and vice versa. They demonstrated that previously learned transsaccadic associations between peripheral and foveal object information facilitate performance in visual search, irrespective of the correctness of these associations. False associations were learned by replacing the presaccadic object with a slightly different object during the saccade. Importantly, participants usually did not notice this object change. This raises the question of whether perception of object continuity is a critical factor in building transsaccadic associations. We disturbed object continuity during learning with a postsaccadic blank or a task-irrelevant shape change. Interestingly, visual search performance revealed that neither disruption of temporal object continuity (blank) nor disruption of spatial object continuity (shape change) impaired transsaccadic learning. Thus, transsaccadic learning seems to be a very robust default mechanism of the visual system that is probably related to the more general concept of action–effect learning. |
Dorothea Wendt; Thomas Brand; Birger Kollmeier An eye-tracking paradigm for analyzing the processing time of sentences with different linguistic complexities Journal Article In: PLoS ONE, vol. 9, no. 6, pp. e100186, 2014. @article{Wendt2014a, An eye-tracking paradigm was developed for use in audiology in order to enable online analysis of the speech comprehension process. This paradigm should be useful in assessing impediments in speech processing. In this paradigm, two scenes, a target picture and a competitor picture, were presented simultaneously with an aurally presented sentence that corresponded to the target picture. At the same time, eye fixations were recorded using an eye-tracking device. The effect of linguistic complexity on language processing time was assessed from eye fixation information by systematically varying linguistic complexity. This was achieved with a sentence corpus containing seven German sentence structures. A novel data analysis method computed the average tendency to fixate the target picture as a function of time during sentence processing. This allowed identification of the point in time at which the participant understood the sentence, referred to as the decision moment. Systematic differences in processing time were observed as a function of linguistic complexity. These differences in processing time may be used to assess the efficiency of cognitive processes involved in resolving linguistic complexity. Thus, the proposed method enables a temporal analysis of the speech comprehension process and has potential applications in speech audiology and psychoacoustics. |
Mike Wendt; Andrea Kiesel; Franziska Geringswald; Sascha Purmann; Rico Fischer In: Experimental Psychology, vol. 61, no. 1, pp. 55–67, 2014. @article{Wendt2014, Current models of cognitive control assume gradual adjustment of processing selectivity to the strength of conflict evoked by distractor stimuli. Using a flanker task, we varied conflict strength by manipulating target and distractor onset. Replicating previous findings, flanker interference effects were larger on trials associated with advance presentation of the flankers compared to simultaneous presentation. Controlling for stimulus and response sequence effects by excluding trials with feature repetitions from stimulus administration (Experiment 1) or from the statistical analyses (Experiment 2), we found a reduction of the flanker interference effect after high-conflict predecessor trials (i.e., trials associated with advance presentation of the flankers) but not after low-conflict predecessor trials (i.e., trials associated with simultaneous presentation of target and flankers). This result supports the assumption of conflict-strength-dependent adjustment of visual attention. The selective adaptation effect after high-conflict trials was associated with an increase in prestimulus pupil diameter, possibly reflecting increased cognitive effort of focusing attention. |
Jessica Werthmann; Matt Field; Anne Roefs; Chantal Nederkoorn; Anita Jansen Attention bias for chocolate increases chocolate consumption - An attention bias modification study Journal Article In: Journal of Behavior Therapy and Experimental Psychiatry, vol. 45, no. 1, pp. 136–143, 2014. @article{Werthmann2014a, Objective The current study examined experimentally whether a manipulated attention bias for food cues increases craving, chocolate intake and motivation to search for hidden chocolates. Method To test the effect of attention for food on subsequent chocolate intake, attention for chocolate was experimentally modified by instructing participants to look at chocolate stimuli ("attend chocolate" group) or at non-food stimuli ("attend shoes" group) during a novel attention bias modification task (antisaccade task). Chocolate consumption, changes in craving and search time for hidden chocolates were assessed. Eye-movement recordings were used to monitor the accuracy during the experimental attention modification task as possible moderator of effects. Regression analyses were conducted to test the effect of attention modification and modification accuracy on chocolate intake, craving and motivation to search for hidden chocolates. Results Results showed that participants with higher accuracy (+1 SD), ate more chocolate when they had to attend to chocolate and ate less chocolate when they had to attend to non-food stimuli. In contrast, for participants with lower accuracy (-1 SD), the results were exactly reversed. No effects of the experimental attention modification on craving or search time for hidden chocolates were found. Limitation We used chocolate as food stimuli so it remains unclear how our findings generalize to other types of food. Conclusion These findings demonstrate further evidence for a link between attention for food and food intake, and provide an indication about the direction of this relationship. © 2013 Elsevier Ltd. All rights reserved. |
Jessica Werthmann; Fritz Renner; Anne Roefs; Marcus J. H. Huibers; Lana Plumanns; Nora Krott; Anita Jansen Looking at food in sad mood: Do attention biases lead emotional eaters into overeating after a negative mood induction? Journal Article In: Eating Behaviors, vol. 15, no. 2, pp. 230–236, 2014. @article{Werthmann2014, Background: Emotional eating is associated with overeating and the development of obesity. Yet, empirical evidence for individual (trait) differences in emotional eating and cognitive mechanisms that contribute to eating during sad mood remain equivocal. Aim: The aim of this study was to test if attention bias for food moderates the effect of self-reported emotional eating during sad mood (vs neutral mood) on actual food intake. It was expected that emotional eating is predictive of elevated attention for food and higher food intake after an experimentally induced sad mood and that attentional maintenance on food predicts food intake during a sad versus a neutral mood. Method: Participants (N. = 85) were randomly assigned to one of the two experimental mood induction conditions (sad/neutral). Attentional biases for high caloric foods were measured by eye tracking during a visual probe task with pictorial food and neutral stimuli. Self-reported emotional eating was assessed with the Dutch Eating Behavior Questionnaire (DEBQ) and ad libitum food intake was tested by a disguised food offer. Results: Hierarchical multivariate regression modeling showed that self-reported emotional eating did not account for changes in attention allocation for food or food intake in either condition. Yet, attention maintenance on food cues was significantly related to increased intake specifically in the neutral condition, but not in the sad mood condition. Discussion: The current findings show that self-reported emotional eating (based on the DEBQ) might not validly predict who overeats when sad, at least not in a laboratory setting with healthy women. Results further suggest that attention maintenance on food relates to eating motivation when in a neutral affective state, and might therefore be a cognitive mechanism contributing to increased food intake in general, but maybe not during sad mood. |
Gregory L. West; Sandrine Mendizabal; Marie Pierre Carrière; Sarah Lippé Linear age-correlated development of inhibitory saccadic trajectory deviations Journal Article In: Developmental Psychology, vol. 50, no. 9, pp. 2285–2290, 2014. @article{West2014, The present study examined development-related differences in saccade curvature during a goal-directed saccade task in the presence of distracting visual information. Participants were individuals who ranged in age from 6 to 30 years. Consistent with previous findings, all participants showed curvature toward the distractor stimulus at shorter saccadic reaction times (SRTs). Chronological age, however, was positively related to participants' ability to inhibit distracting information as revealed by curvature away from the distractor stimulus at longer SRTs. Interestingly, no significant differences in saccadic reaction times were observed. Results are discussed in the context of similar findings comparing older and younger adults and the putative frontal neural mechanisms that contribute to the observed developmental effect. Our present results suggest that saccadic curvature can be used a tool to measure fontal-oculomotor control interaction across the life span and can be further used to examine inhibitory functioning in special pediatric populations (e.g., having brain trauma, attention-deficit/hyperactivity disorder, frontal epilepsy). WABBLE: |
Masha Westerlund; Liina Pylkkänen The role of the left anterior temporal lobe in semantic composition vs. semantic memory Journal Article In: Neuropsychologia, vol. 57, no. 1, pp. 59–70, 2014. @article{Westerlund2014, The left anterior temporal lobe (LATL) is robustly implicated in semantic processing by a growing body of literature. However, these results have emerged from two distinct bodies of work, addressing two different processing levels. On the one hand, the LATL has been characterized as a 'semantic hub׳ that binds features of concepts across a distributed network, based on results from semantic dementia and hemodynamic findings on the categorization of specific compared to basic exemplars. On the other, the LATL has been implicated in combinatorial operations in language, as shown by increased activity in this region associated with the processing of sentences and of basic phrases. The present work aimed to reconcile these two literatures by independently manipulating combination and concept specificity within a minimal MEG paradigm. Participants viewed simple nouns that denoted either low specificity (fish) or high specificity categories (trout) presented in either combinatorial (spotted fish/trout) or non-combinatorial contexts (xhsl fish/trout). By combining these paradigms from the two literatures, we directly compared the engagement of the LATL in semantic memory vs. semantic composition. Our results indicate that although noun specificity subtly modulates the LATL activity elicited by single nouns, it most robustly affects the size of the composition effect when these nouns are adjectivally modified, with low specificity nouns eliciting a much larger effect. We conclude that these findings are compatible with an account in which the specificity and composition effects arise from a shared mechanism of meaning specification. |
Mark Wexler; Thérèse Collins Orthogonal steps relieve saccadic suppression Journal Article In: Journal of vision, vol. 14, no. 2, pp. 1–9, 2014. @article{Wexler2014, Although the retinal position of objects changes with each saccadic eye movement, we perceive the visual world to be stable. How this visual stability or constancy arises is debated. Cancellation accounts propose that the retinal consequences of eye movements are compensated for by an equal-but-opposite eye movement signal. Assumption accounts propose that saccade-induced retinal displacements are ignored because we have a prior belief in a stable world. Saccadic suppression of displacement-the fact that small displacements of the visual targets during saccades go unnoticed-argues in favor of assumption accounts. Extinguishing the target before the displacement unmasks it, arguing in favor of cancellation accounts. We show that an irrelevant displacement of the target orthogonal to saccade direction unmasks displacements parallel to saccade direction, and therefore relieves saccadic suppression of displacement. This result suggests that visual stability arises from the interplay between cancellation and assumption mechanisms: When the post-saccadic target position falls within an elliptic region roughly equivalent to habitual saccadic variability, displacements are not seen and stability is assumed. When the displacements fall outside this region, as with our orthogonal steps, displacements are seen and positions are remapped. |
Nicole C. White; Connor Reid; Timothy N. Welsh Responses of the human motor system to observing actions across species: A transcranial magnetic stimulation study Journal Article In: Brain and Cognition, vol. 92, pp. 11–18, 2014. @article{White2014, Ample evidence suggests that the role of the mirror neuron system (MNS) in monkeys is to represent the meaning of actions. The MNS becomes active in monkeys during execution, observation, and auditory experience of meaningful, object-oriented actions, suggesting that these cells represent the same action based on a variety of cues. The present study sought to determine whether the human motor system, part of the putative human MNS, similarly represents and reflects the meaning of actions rather than simply the mechanics of the actions. To this end, transcranial magnetic stimulation (TMS) of primary motor cor- tex was used to generate motor-evoked potentials (MEPs) from muscles involved in grasping while par- ticipants viewed object-oriented grasping actions performed by either a human, an elephant, a rat, or a body-less robotic arm. The analysis of MEP amplitudes suggested that activity in primary motor cortex during action observation was greatest during observation of the grasping actions of the rat and elephant, and smallest for the human and robotic arm. Based on these data, we conclude that the human action observation system can represent actions executed by non-human animals and shows sensitivity to spe- cies-specific differences in action mechanics. |
Corinne R. Vokoun; Xin Huang; Meyer B. Jackson; Michele A. Basso Response normalization in the superficial layers of the superior colliculus as a possible mechanism for saccadic averaging Journal Article In: Journal of Neuroscience, vol. 34, no. 23, pp. 7976–7987, 2014. @article{Vokoun2014, How does the brain decide where to look? Neuronal networks within the superior colliculus (SC) encode locations of intended eye movements. When faced with multiple targets, the relative activities of neuronal populations compete for the selection of a saccade. However, the computational principles underlying saccadic choices remain poorly understood. We used voltage imaging of slices of rat SC to record circuit dynamics of population responses to single- and dual-site electrical stimulation to begin to reveal some of the principles of how populations of neurons interact. Stimulation of two distant sites simultaneously within the SC produced two distinct peaks of activity, whereas stimulation of two nearby sites simultaneously exhibited a single, merged peak centered between the two sites. The distances required to produce merged peaks of activity corresponded to target separations that evoked averaging saccades in humans performing a corresponding dual target task. The merged activity was well accounted for by a linear weighed summation and a divisive normalization of the responses evoked by the single-site stimulations. Interestingly, the merging of activity occurred within the superficial SC, suggesting a novel pathway for saccadic eye movement choice. |
Christian Vorstius; Ralph Radach; Christopher J. Lonigan Eye movements in developing readers: A comparison of silent and oral sentence reading Journal Article In: Visual Cognition, vol. 22, no. 3, pp. 458–485, 2014. @article{Vorstius2014, We present sentence reading data from a large-scale study with children (N = 632), focusing on three key research questions. (1) What are the trajectories of reading development in oral as compared to silent reading? (2) How are word frequency effects developing and are changes differentially affected by reading mode? (3) Are there systematic differences between better and weaker comprehenders when reading silently vs. aloud? Results illuminate a number of differences between reading modes, including more and prolonged fixations in oral reading, along with less inter-word regressions and attenuated effects of word frequency. Weaker comprehenders were slower, especially in oral reading and showed less flexibility in the allocation of word processing time. Differences between reading modes can be explained by additional processing demands imposed by concurrent articulation and eye?voice coordination when reading aloud.$backslash$nWe present sentence reading data from a large-scale study with children (N = 632), focusing on three key research questions. (1) What are the trajectories of reading development in oral as compared to silent reading? (2) How are word frequency effects developing and are changes differentially affected by reading mode? (3) Are there systematic differences between better and weaker comprehenders when reading silently vs. aloud? Results illuminate a number of differences between reading modes, including more and prolonged fixations in oral reading, along with less inter-word regressions and attenuated effects of word frequency. Weaker comprehenders were slower, especially in oral reading and showed less flexibility in the allocation of word processing time. Differences between reading modes can be explained by additional processing demands imposed by concurrent articulation and eye?voice coordination when reading aloud. |
Simone Vossel; Markus Bauer; Christoph Mathys; Rick A. Adams; Raymond J. Dolan; Klaas E. Stephan; Karl J. Friston Cholinergic stimulation enhances Bayesian belief updating in the deployment of spatial attention Journal Article In: Journal of Neuroscience, vol. 34, no. 47, pp. 15735–15742, 2014. @article{Vossel2014, The exact mechanisms whereby the cholinergic neurotransmitter system contributes to attentional processing remain poorly understood. Here, we applied computational modeling to psychophysical data (obtained from a spatial attention task) under a psychopharmacological challenge with the cholinesterase inhibitor galantamine (Reminyl). This allowed us to characterize the cholinergic modulation of selective attention formally, in terms of hierarchical Bayesian inference. In a placebo-controlled, within-subject, crossover design, 16 healthy human subjects performed a modified version of Posner's location-cueing task in which the proportion of validly and invalidly cued targets (percentage of cue validity, % CV) changed over time. Saccadic response speeds were used to estimate the parameters of a hierarchical Bayesian model to test whether cholinergic stimulation affected the trial-wise updating of probabilistic beliefs that underlie the allocation of attention or whether galantamine changed the mapping from those beliefs to subsequent eye movements. Behaviorally, galantamine led to a greater influence of probabilistic context (% CV) on response speed than placebo. Crucially, computational modeling suggested this effect was due to an increase in the rate of belief updating about cue validity (as opposed to the increased sensitivity of behavioral responses to those beliefs). We discuss these findings with respect to cholinergic effects on hierarchical cortical processing and in relation to the encoding of expected uncertainty or precision. |
Simone Vossel; Christoph Mathys; Jean Daunizeau; Markus Bauer; Jon Driver; Karl J. Friston; Klaas E. Stephan Spatial attention, precision, and bayesian inference: A study of saccadic response speed Journal Article In: Cerebral Cortex, vol. 24, no. 6, pp. 1436–1450, 2014. @article{Vossel2014a, Inferring the environment's statistical structure and adapting behavior accordingly is a fundamental modus operandi of the brain. A simple form of this faculty based on spatial attentional orienting can be studied with Posner's location-cueing paradigm in which a cue indicates the target location with a known probability. The present study focuses on a more complex version of this task, where probabilistic context (percentage of cue validity) changes unpredictably over time, thereby creating a volatile environment. Saccadic response speed (RS) was recorded in 15 subjects and used to estimate subject-specific parameters of a Bayesian learning scheme modeling the subjects' trial-by-trial updates of beliefs. Different response models-specifying how computational states translate into observable behavior-were compared using Bayesian model selection. Saccadic RS was most plausibly explained as a function of the precision of the belief about the causes of sensory input. This finding is in accordance with current Bayesian theories of brain function, and specifically with the proposal that spatial attention is mediated by a precision-dependent gain modulation of sensory input. Our results provide empirical support for precision-dependent changes in beliefs about saccade target locations and motivate future neuroimaging and neuropharmacological studies of how Bayesian inference may determine spatial attention. |
Daniel Voyer; Jean Saint-Aubin; Christine Cook Strategies and pseudoneglect on luminance judgments: An eye-tracking investigation Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 40, no. 5, pp. 1789–1798, 2014. @article{Voyer2014, Four experiments were conducted to examine competing hypotheses relevant to the strategies believed to underlie pseudoneglect. The 4 experiments implemented manipulations relevant to eye-movement monitoring to evaluate the potential role of a comparison versus a global strategy in producing a left bias in a task involving a judgment of luminosity. Experiment 1 required task completion under free viewing while eye movements were monitored. The link between the observed behavioral bias and the strategy inferred from the pattern of eye movements was then examined. In Experiment 2, the eye-movement manipulation promoted reliance on a comparison strategy. Experiment 3 forced participants to use a global strategy. Finally, Experiment 4 also forced participants to use a global strategy, but it minimized the influence of memory in the task. Results from all 4 experiments supported the preponderance of the global strategy as driving the left bias. In Experiment 1, the magnitude of the bias decreased as the number of comparison increased. In Experiment 2, the left bias disappeared. Finally, in Experiments 3 and 4, the bias was the largest in the present series of experiments. These findings are discussed in the context of existing explanations of pseudoneglect. |
Stephanie Waechter; Andrea L. Nelson; Caitlin A. Wright; Ashley Hyatt; Jonathan Oakman Measuring attentional bias to threat: Reliability of dot probe and eye movement indices Journal Article In: Cognitive Therapy and Research, vol. 38, no. 3, pp. 313–333, 2014. @article{Waechter2014, A variety of methodological paradigms, including dot probe and eye movement tasks, have been used to examine attentional biases to threat in anxiety disorders. Unfortunately, little attention has been devoted to the psychometric properties of measures from these paradigms. In the current study, participants selected for high and low social anxiety completed a dot probe and eye movement task using angry, disgust and happy facial expressions paired with neutral expressions. Results indicated that dot probe bias scores, eye movement first fixa- tion indices, and eye movement proportions of viewing time in the first 1,500 ms had unacceptably low reliability. However, eye movement indices of attentional bias over the full 5,000 ms time course had excellent reliability. Individuals' dot probe and eye movement biases were largely uncorrelated across the two tasks and demonstrated little relation with social anxiety scores. Implications for future research are discussed. |
David V. Walsh; Lei Liu Adaptation to a simulated central scotoma during visual search training Journal Article In: Vision Research, vol. 96, pp. 75–86, 2014. @article{Walsh2014, Patients with a central scotoma usually use a preferred retinal locus (PRL) consistently in daily activities. The selection process and time course of the PRL development are not well understood. We used a gaze-contingent display to simulate an isotropic central scotoma in normal subjects while they were practicing a difficult visual search task. As compared to foveal search, initial exposure to the simulated scotoma resulted in prolonged search reaction time, many more fixations and unorganized eye movements during search. By the end of a 1782-trial training with the simulated scotoma, the search performance improved to within 25% of normal foveal search. Accompanying the performance improvement, there were also fewer fixations, fewer repeated fixations in the same area of the search stimulus and a clear tendency of using one area near the border of the scotoma to identify the search target. The results were discussed in relation to natural development of PRL in central scotoma patients and potential visual training protocols to facilitate PRL development. |
Aiping Wang; Wei Zhou; Hua Shu; Ming Yan Reading proficiency modulates parafoveal processing efficiency: Evidence from reading Chinese as a second language Journal Article In: Acta Psychologica, vol. 152, pp. 29–33, 2014. @article{Wang2014g, In the present study, we manipulated different types of information available in the parafovea during the reading of Chinese sentences and examined how native Korean readers who learned Chinese as a second language make use of the parafoveal information. Results clearly indicate that, only identical and orthographically similar previews facilitated processing of the target words when they were subsequently fixated. More critically, more parafoveal information was obtained by subjects with higher reading proficiency. These results suggest that, mainly low-level features of the parafoveal words are obtained by the non-native Chinese readers and less attentional resources are available for the readers with lower reading proficiency, thereby causing a reduction of the perceptual span. |
Benchi Wang; Matthew D. Hilchey; Xiaohua Cao; Zhiguo Wang The spatial distribution of inhibition of return revisited: No difference found between manual and saccadic responses Journal Article In: Neuroscience Letters, vol. 578, pp. 128–132, 2014. @article{Wang2014a, Inhibition of return (IOR) commonly refers to the effect of prolonged response times to targets at previously attended locations. It is a well-documented fact that IOR is not restricted to previously attended locations, but rather has a spatial gradient. Based on a myriad of manual/saccadic dissociations, many researchers now believe that there are at least two forms of IOR completely dissociable on the basis of response type. The present study evaluated whether these two forms of IOR are encoded in similar representations of space. Across a range of conditions, there was little indication that the two forms could be differentiated on the basis of their spatial distributions. Furthermore, the present study also found that the gradient of IOR was steepest for cues appearing nearest fixation. |
C. -A. Wang; S. E. Boehnke; Laurent Itti; D. P. Munoz Transient pupil response is modulated by contrast-based saliency Journal Article In: Journal of Neuroscience, vol. 34, no. 2, pp. 408–417, 2014. @article{Wang2014b, The sudden appearance of a novel stimulus in the environment initiates a series of orienting responses that include coordinated shifts of gaze and attention, and also transient changes in pupil size. Although numerous studies have identified a significant effect of stimulus saliency on shifts of gaze and attention, saliency effects on pupil size are less understood. To examine salience-evoked pupil responses, we presented visual, auditory, or audiovisual stimuli while monkeys fixated a central visual spot. Transient pupil dilation was elicited after visual stimulus presentation regardless of target luminance relative to background, and auditory stimuli also evoked similar pupil responses. Importantly, the evoked pupil response was modulated by contrast-based saliency, with faster and larger pupil responses following the presentation of more salient stimuli. The initial transient component of pupil dilation was qualitatively similar to that evoked by weak microstimulation of the midbrain superior colliculus. The pupil responses elicited by audiovisual stimuli were well predicted by a linear summation of each modality response. Together, the results suggest that the transient pupil response, as one component of orienting, is modulated by contrast-based saliency, and the superior colliculus is likely involved in its coordination. |
Kohitij Kar; Bart Krekelberg Transcranial alternating current stimulation attenuates visual motion adaptation Journal Article In: Journal of Neuroscience, vol. 34, no. 21, pp. 7334–7340, 2014. @article{Kar2014, Transcranial alternating current stimulation (tACS) is used in clinical applications and basic neuroscience research. Although its behavioral effects are evident from prior reports, current understanding of the mechanisms that underlie these effects is limited. We used motion perception, a percept with relatively well known properties and underlying neural mechanisms to investigate tACS mechanisms. Healthy human volunteers showed a surprising improvement in motion sensitivity when visual stimuli were paired with 10 Hz tACS. In addition, tACS reduced the motion-after effect, and this reduction was correlated with the improvement in motion sensitivity. Electrical stimulation had no consistent effect when applied before presenting a visual stimulus or during recovery from motion adaptation. Together, these findings suggest that perceptual effects of tACS result from an attenuation of adaptation. Important consequences for the practical use of tACS follow from our work. First, because this mechanism interferes only with adaptation, this suggests that tACS can be targeted at subsets of neurons (by adapting them), even when the applied currents spread widely throughout the brain. Second, by interfering with adaptation, this mechanism provides a means by which electrical stimulation can generate behavioral effects that outlast the stimulation. |
Hossein Karimi; Kumiko Fukumura; Fernanda Ferreira; Martin J. Pickering The effect of noun phrase length on the form of referring expressions Journal Article In: Memory & Cognition, vol. 42, no. 6, pp. 993–1009, 2014. @article{Karimi2014, The length of a noun phrase has been shown to influence choices such as syntactic role assignment (e.g., whether the noun phrase is realized as the subject or the object). But does length also affect the choice between different forms of referring expressions? Three experiments investigated the effect of antecedent length on the choice between pronouns (e.g., he) and repeated nouns (e.g., the actor) using a sentence-continuation paradigm. Experiments 1 and 2 found an effect of antecedent length on written continuations: Participants used more pronouns (relative to repeated nouns) when the antecedent was longer than when it was shorter. Experiment 3 used a spoken continuation task and replicated the effect of antecedent length on the choice of referring expressions. Taken together, the results suggest that longer antecedents increase the likelihood of pronominal reference. The results support theories arguing that length enhances the accessibility of the associated entity through richer semantic encoding. |
Koji Kashihara; Kazuo Okanoya; Nobuyuki Kawai Emotional attention modulates microsaccadic rate and direction Journal Article In: Psychological Research, vol. 78, no. 2, pp. 166–179, 2014. @article{Kashihara2014, Involuntary microsaccades and voluntary saccades reflect human brain activities during attention and cognitive tasks. Our eye movements can also betray our emotional state. However, the effects of attention to emotion on microsaccadic activity remain unknown. The present study was conducted in healthy volunteers to investigate the effects of devoting attention to exogenous emotional stimuli on microsaccadic response, with change in pupil size as an index of sympathetic nervous system activity. Event-related responses to unpleasant images significantly inhibited the rate of microsaccade appearance and altered pupil size (Experiment 1). Additionally, microsaccadic responses to covert orienting of attention to emotional stimuli appeared significantly in the anti-direction to a target, with a fast reaction time (Experiment 2). Therefore, we concluded that attentional shifts induced by exogenous emotional stimuli can modulate microsaccadic activities. Future studies of the interaction between miniature eye movements and emotion may be beneficial in the assessment of pathophysiological responses in mental disorders. |
Ioanna Katidioti; Jelmer P. Borst; Niels A. Taatgen What happens when we switch tasks: Pupil Dilation in Multitasking Journal Article In: Journal of Experimental Psychology: Applied, vol. 20, no. 4, pp. 380–396, 2014. @article{Katidioti2014, Interruption studies typically focus on external interruptions, even though self-interruptions occur at least as often in real work environments. In this article, we therefore contrast external interruptions with self-interruptions. Three multitasking experiments were conducted, in which we examined changes in pupil size when participants switched from a primary to a secondary task. Results showed an increase in pupil dilation several seconds before a self-interruption, which we could attribute to the decision to switch. This indicates that the decision takes a relatively large amount of time. This was supported by the fact that in Experiment 2, participants were significantly slower on the self-interruption blocks than on the external interruption blocks. These findings suggest that the decision to switch is costly, but may also be open for modification through appropriate training. In addition, we propose that if one must switch tasks, it can be more efficient to implement a forced switch after the completion of a subtask instead of leaving the decision to the user. |
Lisandro N. Kaunitz; Juan E. Kamienkowski; Alexander Varatharajah; Mariano Sigman; Rodrigo Quian Quiroga; Matias J. Ison Looking for a face in the crowd: Fixation-related potentials in an eye-movement visual search task Journal Article In: NeuroImage, vol. 89, pp. 297–305, 2014. @article{Kaunitz2014, Despite the compelling contribution of the study of event related potentials (ERPs) and eye movements to cognitive neuroscience, these two approaches have largely evolved independently. We designed an eye-movement visual search paradigm that allowed us to concurrently record EEG and eye movements while subjects were asked to find a hidden target face in a crowded scene with distractor faces. Fixation event-related potentials (fERPs) to target and distractor stimuli showed the emergence of robust sensory components associated with the perception of stimuli and cognitive components associated with the detection of target faces. We compared those components with the ones obtained in a control task at fixation: qualitative similarities as well as differences in terms of scalp topography and latency emerged between the two. By using single trial analyses, fixations to target and distractors could be decoded from the EEG signals above chance level in 11 out of 12 subjects. Our results show that EEG signatures related to cognitive behavior develop across spatially unconstrained exploration of natural scenes and provide a first step towards understanding the mechanisms of target detection during natural search. |
Kerry Kawakami; Amanda Williams; David M. Sidhu; Becky L. Choma; Rosa Rodriguez-Bailón; Elena Cañadas; Derek Chung; Kurt Hugenberg An eye for the I: Preferential attention to the eyes of ingroup members. Journal Article In: Journal of Personality and Social Psychology, vol. 107, no. 1, pp. 1–20, 2014. @article{Kawakami2014, Human faces, and more specifically the eyes, play a crucial role in social and nonverbal communication because they signal valuable information about others. It is therefore surprising that few studies have investigated the impact of intergroup contexts and motivations on attention to the eyes of ingroup and outgroup members. Four experiments investigated differences in eye gaze to racial and novel ingroups using eye tracker technology. Whereas Studies 1 and 3 demonstrated that White participants attended more to the eyes of White compared to Black targets, Study 2 showed a similar pattern of attention to the eyes of novel ingroup and outgroup faces. Studies 3 and 4 also provided new evidence that eye gaze is flexible and can be meaningfully influenced by current motivations. Specifically, instructions to individuate specific social categories increased attention to the eyes of target group members. Furthermore, the latter experiments demonstrated that preferential attention to the eyes of ingroup members predicted important intergroup biases such as recognition of ingroup over outgroup faces (i.e., the own-race bias; Study 3) and willingness to interact with outgroup members (Study 4). The implication of these findings for general theorizing on face perception, individuation processes, and intergroup relations are discussed. |
Stephanie A. H. Jones; Christopher D. Cowper-Smith; David A. Westwood Directional interactions between current and prior saccades Journal Article In: Frontiers in Human Neuroscience, vol. 8, pp. 872, 2014. @article{Jones2014, One way to explore how prior sensory and motor events impact eye movements is to ask someone to look to targets located about a central point, returning gaze to the central point after each eye movement. Concerned about the contribution of this return to center movement, Anderson et al. (2008) used a sequential saccade paradigm in which participants made a continuous series of saccades to peripheral targets that appeared to the left or right of the currently fixated location in a random sequence (the next eye movement began from the last target location). Examining the effects of previous saccades (n-x) on current saccade latency (n), they found that saccadic reaction times (RT) were reduced when the direction of the current saccade matched that of a preceding saccade (e.g., two left saccades), even when the two saccades in question were separated by multiple saccades in any direction. We examined if this pattern extends to conditions in which targets appear inside continuously marked locations that provide stable visual features (i.e., target "placeholders") and when saccades are prompted by central arrows. Participants completed 3 conditions: peripheral targets (PT; continuous, sequential saccades to peripherally presented targets) without placeholders; PT with placeholders; and centrally presented arrows (CA; left or right pointing arrows at the currently fixated location instructing participants to saccade to the left or right). We found reduced saccadic RT when the immediately preceding saccade (n-1) was in the same (vs. opposite) direction in the PT without placeholders and CA conditions. This effect varied when considering the effect of the previous 2-5 (n-x) saccades on current saccade latency (n). The effects of previous eye movements on current saccade latency may be determined by multiple, time-varying mechanisms related to sensory (i.e., retinotopic location), motor (i.e., saccade direction), and environmental (i.e., persistent visual objects) factors. |
D. Jonikaitis; Artem V. Belopolsky Target-distractor competition in the oculomotor system is spatiotopic Journal Article In: Journal of Neuroscience, vol. 34, no. 19, pp. 6687–6691, 2014. @article{Jonikaitis2014, In natural scenes, multiple visual stimuli compete for selection; however, each saccade displaces the stimulus representations in retinotopicaly organized visual and oculomotor maps. In the present study, we used saccade curvature to investigate whether oculomotor competition across eye movements is represented in retinotopic or spatiotopic coordinates. Participants performed a sequence of saccades and we induced oculomotor competition by briefly presenting a task-irrelevant distractor at different times during the saccade sequence. Despite the intervening saccade, the second saccade curved away from a spatial representation of the distractor that was presented before the first saccade. Furthermore, the degree of saccade curvature increased with the salience of the distractor presented before the first saccade. The results suggest that spatiotopic representations of target-distractor competition are crucial for successful interaction with objects of interest despite the intervening eye movements. |
Timothy R. Jordan; Abubaker A. A. Almabruk; Eman A. Gadalla; Victoria A. McGowan; Sarah J. White; Lily Abedipour; Kevin B. Paterson Reading direction and the central perceptual span: Evidence from Arabic and English Journal Article In: Psychonomic Bulletin & Review, vol. 21, no. 2, pp. 505–511, 2014. @article{Jordan2014, In English and other alphabetic languages read from left to right, useful information acquired during each fixational pause is generally reported to extend much further to the right of each fixation than to the left. However, the asymmetry of the perceptual span for alphabetic languages read in the opposite direction (i.e., from right to left) has received very little attention in empirical research. Accordingly, we investigated the perceptual span for Arabic, which is one of the world's most widely read languages and is read from right to left, using a gaze-contingent window paradigm in which a region of text was displayed normally around each point of fixation, while text outside this region was obscured. Skilled Arabic readers who were bilingual in Arabic and English read Arabic and English sentences while a window of normal text extended symmetrically 0.5(o) to the left and right of fixation or asymmetrically, by increasing this window to 1.5(o) or 2.5(o) to either the left or the right. When English was read, performance across window conditions was superior when windows extended rightward. However, when Arabic was read, performance was superior when windows extended leftward and was essentially the reverse of that observed for English. These findings show for the first time that a leftward asymmetry in the central perceptual span occurs when Arabic is read and, for the first time in over 30 years, provide a new indication that the perceptual span for alphabetic languages is modified by the overall direction of reading. |
Timothy R. Jordan; Victoria A. McGowan; Kevin B. Paterson Reading with filtered fixations: Adult age differences in the effectiveness of low-level properties of text within central vision Journal Article In: Psychology and Aging, vol. 29, no. 2, pp. 229–235, 2014. @article{Jordan2014a, When reading, low-level visual properties of text are acquired from central vision during brief fixational pauses, but the effectiveness of these properties may differ in older age. To investigate, a filtering technique displayed the low, medium, or high spatial frequencies of text falling within central vision as young (18-28 years) and older (65+ years) adults read. Reading times for normal text did not differ across age groups, but striking differences in the effectiveness of spatial frequencies were observed. Consequently, even when young and older adults read equally well, the effectiveness of spatial frequencies in central vision differs markedly in older age. |
Holly S. S. L. Joseph; Elizabeth Wonnacott; Paul Forbes; Kate Nation Becoming a written word: Eye movements reveal order of acquisition effects following incidental exposure to new words during silent reading Journal Article In: Cognition, vol. 133, no. 1, pp. 238–248, 2014. @article{Joseph2014, We know that from mid-childhood onwards most new words are learned implicitly via reading; however, most word learning studies have taught novel items explicitly. We examined incidental word learning during reading by focusing on the well-documented finding that words which are acquired early in life are processed more quickly than those acquired later. Novel words were embedded in meaningful sentences and were presented to adult readers early (day 1) or later (day 2) during a five-day exposure phase. At test adults read the novel words in semantically neutral sentences. Participants' eye movements were monitored throughout exposure and test. Adults also completed a surprise memory test in which they had to match each novel word with its definition. Results showed a decrease in reading times for all novel words over exposure, and significantly longer total reading times at test for early than late novel words. Early-presented novel words were also remembered better in the offline test. Our results show that order of presentation influences processing time early in the course of acquiring a new word, consistent with partial and incremental growth in knowledge occurring as a function of an individual's experience with each word. |
Johanna K. Kaakinen; Jukka Hyönä Task relevance induces momentary changes in the functional visual field during reading Journal Article In: Psychological Science, vol. 25, no. 2, pp. 626–632, 2014. @article{Kaakinen2014, In the research reported here, we examined whether task demands can induce momentary tunnel vision during reading. More specifically, we examined whether the size of the functional visual field depends on task relevance. Forty participants read an expository text with a specific task in mind while their eye movements were recorded. A display-change paradigm with random-letter strings as preview masks was used to study the size of the functional visual field within sentences that contained task-relevant and task-irrelevant information. The results showed that orthographic parafoveal-on-foveal effects and preview benefits were observed for words within task-irrelevant but not task-relevant sentences. The results indicate that the size of the functional visual field is flexible and depends on the momentary processing demands of a reading task. The higher cognitive processing requirements experienced when reading task-relevant text rather than task-irrelevant text induce momentary tunnel vision, which narrows the functional visual field. |
Johanna K. Kaakinen; Henri Olkoniemi; Taina Kinnari; Jukka Hyönä Processing of written irony: An eye movement study Journal Article In: Discourse Processes, vol. 51, no. 4, pp. 287–311, 2014. @article{Kaakinen2014a, We examined processing of written irony by recording readers' eye movements while they read target phrases embedded either in ironic or non-ironic story context. After reading each story, participants responded to a text memory question and an inference question tapping into the understanding of the meaning of the target phrase. The results of Experiment 1 (N ¼ 52) showed that readers were more likely to reread ironic than non-ironic target sentences during first-pass reading as well as during later look-backs. Experiment 2 (N ¼ 60) examined individual differences related to working memory capacity (WMC), Sarcasm Self-Report Scale (SSS), and need for cognition (NFC) in the processing of irony. The results of Experiment 2 suggest that WMC, but not SSS or NFC, plays a role in how readers resolve the meaning of ironic utterances. High WMC was related to increased probability of initiating first-pass rereadings in ironic compared with literal sentences. The results of these two experiments suggest that the processing of (unconventional) irony does require extra processing effort and that the effects are localized in the ironic utterances. |
R. M. Kalwani; Siddhartha Joshi; Joshua I. Gold Phasic activation of individual neurons in the locus ceruleus/subceruleus complex of monkeys reflects rewarded decisions to go but not stop Journal Article In: Journal of Neuroscience, vol. 34, no. 41, pp. 13656–13669, 2014. @article{Kalwani2014, Neurons in the brainstem nucleus locus ceruleus (LC) often exhibit phasic activation in the context of simple sensory-motor tasks. The functional role of this activation, which leads to the release of norepinephrine throughout the brain, is not yet understood in part because the conditions under which it occurs remain in question. Early studies focused on the relationship of LC phasic activation to salient sensory events, whereas more recent work has emphasized its timing relative to goal-directed behavioral responses, possibly representing the end of a sensory-motor decision process. To better understand the relationship between LC phasic activation and sensory, motor, and decision processing, we recorded spiking activity of neurons in the LC+ (LC and the adjacent, norepinephrine-containing subceruleus nucleus) of monkeys performing a countermanding task. The task required the monkeys to occasionally withhold planned, saccadic eye movements to a visual target. We found that many well isolated LC+ units responded to both the onset of the visual cue instructing the monkey to initiate the saccade and again after saccade onset, even when it was initiated erroneously in the presence of a stop signal. Many of these neurons did not respond to saccades made outside of the task context. In contrast, neither the appearance of the stop signal nor the successful withholding of the saccade elicited an LC+ response. Therefore, LC+ phasic activation encodes sensory and motor events related to decisions to execute, but not withhold, movements, implying a functional role in goal-directed actions, but not necessarily more covert forms of processing. |
Marc R. Kamke; Alexander E. Ryan; Martin V. Sale; Megan E. J. Campbell; Stephan Riek; Timothy J. Carroll; Jason B. Mattingley Visual spatial attention has opposite effects on bidirectional plasticity in the human motor cortex Journal Article In: Journal of Neuroscience, vol. 34, no. 4, pp. 1475–1480, 2014. @article{Kamke2014, Long-term potentiation (LTP) and long-term depression (LTD) are key mechanisms of synaptic plasticity that are thought to act in concert to shape neural connections. Here we investigated the influence of visual spatial attention on LTP-like and LTD-like plasticity in the human motor cortex. Plasticity was induced using paired associative stimulation (PAS), which involves repeated pairing of peripheral nerve stimulation and transcranial magnetic stimulation to alter functional responses in the thumb area of the primary motor cortex. PAS-induced changes in cortical excitability were assessed using motor-evoked potentials. During plasticity induction, participants directed their attention to one of two visual stimulus streams located adjacent to each hand. When participants attended to visual stimuli located near the left thumb, which was targeted by PAS, LTP-like increases in excitability were significantly enhanced, and LTD-like decreases in excitability reduced, relative to when they attended instead to stimuli located near the right thumb. These differential effects on (bidirectional) LTP-like and LTD-like plasticity suggest that voluntary visual attention can exert an important influence on the functional organization of the motor cortex. Specifically, attention acts to both enhance the strengthening and suppress the weakening of neural connections representing events that fall within the focus of attention. |
Kei Kanari; Hirohiko Kaneko Standard deviation of luminance distribution affects lightness and pupillary response Journal Article In: Journal of the Optical Society of America A, vol. 31, no. 12, pp. 2795–2805, 2014. @article{Kanari2014, We examined whether the standard deviation (SD) of luminance distribution serves as information of illumination. We measured the lightness of a patch presented in the center of a scrambled-dot pattern while manipulating the SD of the luminance distribution. Results showed that lightness decreased as the SD of the surround stimulus increased. We also measured pupil diameter while viewing a similar stimulus. The pupil diameter decreased as the SD of luminance distribution of the stimuli increased. We confirmed that these results were not obtained because of the increase of the highest luminance in the stimulus. Furthermore, results of field measurements revealed a correlation between the SD of luminance distribution and illuminance in natural scenes. These results indicated that the visual system refers to the SD of the luminance distribution in the visual stimulus to estimate the scene illumination. |
Min Suk Kang; Geoffrey F. Woodman The neurophysiological index of visual working memory maintenance is not due to load dependent eye movements Journal Article In: Neuropsychologia, vol. 56, no. 1, pp. 63–72, 2014. @article{Kang2014, The Contralateral Delayed Activity (CDA) is slow negative potential found during a variety of tasks, providing an important measure of the representation of information in visual working memory. However, it is studied using stimulus arrays in which the to-be-remembered objects are shown in the periphery of the left or the right visual field. Our goal was to determine whether fixational eye movements in the direction of the memoranda might underlie the CDA. We found that subjects' gaze was shifted toward the visual field of the memoranda during the retention interval, with its magnitude increasing with the set size. However, the CDA was clearly observed even when the subjects' gaze shifts were absent. In addition, the magnitude of the subjects' gaze shifts was unrelated to their visual working memory capacity measured with behavioral data, unlike the CDA. Finally, the onset latency of the set size dependent eye movements followed the onset of the set size dependent CDA. Thus, our findings clearly show that the CDA does not represent a simple inability to maintain fixation during visual working memory maintenance, but that this neural index of representation in working memory appears to induce eye movements toward the locations of the objects being remembered. |
David C. Jangraw; Ansh Johri; Meron Gribetz; Paul Sajda NEDE: An open-source scripting suite for developing experiments in 3D virtual environments Journal Article In: Journal of Neuroscience Methods, vol. 235, pp. 245–251, 2014. @article{Jangraw2014, Background: As neuroscientists endeavor to understand the brain's response to ecologically valid scenarios, many are leaving behind hyper-controlled paradigms in favor of more realistic ones. This movement has made the use of 3D rendering software an increasingly compelling option. However, mastering such software and scripting rigorous experiments requires a daunting amount of time and effort. New method: To reduce these startup costs and make virtual environment studies more accessible to researchers, we demonstrate a naturalistic experimental design environment (NEDE) that allows experimenters to present realistic virtual stimuli while still providing tight control over the subject's experience. NEDE is a suite of open-source scripts built on the widely used Unity3D game development software, giving experimenters access to powerful rendering tools while interfacing with eye tracking and EEG, randomizing stimuli, and providing custom task prompts. Results: Researchers using NEDE can present a dynamic 3D virtual environment in which randomized stimulus objects can be placed, allowing subjects to explore in search of these objects. NEDE interfaces with a research-grade eye tracker in real-time to maintain precise timing records and sync with EEG or other recording modalities. Comparison with existing methods: Python offers an alternative for experienced programmers who feel comfortable mastering and integrating the various toolboxes available. NEDE combines many of these capabilities with an easy-to-use interface and, through Unity's extensive user base, a much more substantial body of assets and tutorials. Conclusions: Our flexible, open-source experimental design system lowers the barrier to entry for neuroscientists interested in developing experiments in realistic virtual environments. |
David C. Jangraw; Jun Wang; Brent J. Lance; Shih Fu Chang; Paul Sajda Neurally and ocularly informed graph-based models for searching 3D environments Journal Article In: Journal of Neural Engineering, vol. 11, no. 4, pp. 1–13, 2014. @article{Jangraw2014a, OBJECTIVE: As we move through an environment, we are constantly making assessments, judgments and decisions about the things we encounter. Some are acted upon immediately, but many more become mental notes or fleeting impressions-our implicit 'labeling' of the world. In this paper, we use physiological correlates of this labeling to construct a hybrid brain-computer interface (hBCI) system for efficient navigation of a 3D environment. APPROACH: First, we record electroencephalographic (EEG), saccadic and pupillary data from subjects as they move through a small part of a 3D virtual city under free-viewing conditions. Using machine learning, we integrate the neural and ocular signals evoked by the objects they encounter to infer which ones are of subjective interest to them. These inferred labels are propagated through a large computer vision graph of objects in the city, using semi-supervised learning to identify other, unseen objects that are visually similar to the labeled ones. Finally, the system plots an efficient route to help the subjects visit the 'similar' objects it identifies. MAIN RESULTS: We show that by exploiting the subjects' implicit labeling to find objects of interest instead of exploring naively, the median search precision is increased from 25% to 97%, and the median subject need only travel 40% of the distance to see 84% of the objects of interest. We also find that the neural and ocular signals contribute in a complementary fashion to the classifiers' inference of subjects' implicit labeling. SIGNIFICANCE: In summary, we show that neural and ocular signals reflecting subjective assessment of objects in a 3D environment can be used to inform a graph-based learning model of that environment, resulting in an hBCI system that improves navigation and information delivery specific to the user's interests. |
Wolfgang Jaschinski Pupil size affects measures of eye position in video eye tracking: Implications for recording vergence accuracy Journal Article In: Journal of eye movement research, vol. 9, no. 4, pp. 1–14, 2014. @article{Jaschinski2014, Video eye trackers rely on the position of the pupil centre. However, the pupil centre can shift when the pupil size changes. This pupillary artefact is investigated for binocular vergence accuracy (i.e. fixation disparity) in near vision where the pupil is smaller in the binocular test phase than in the monocular calibration. A regression between recordings of pupil size and fixation disparity allows correcting the pupillary artefact. This corrected fixation disparity appeared to be favourable with respect to reliability and validity, i.e. the correlation of fixation disparity versus heterophoria. The findings provide a quantitative estimation of the pupillary artefact on measured eye position as function of viewing disance and luminance, both for measures of monocular and binocular eye position. |
Pavitra Jayaramachandran; Frank A. Proudlock; Nita Odedra; Irene Gottlob; Rebecca J. McLean A randomized controlled trial comparing soft contact lens and rigid gas-permeable lens wearing in infantile nystagmus Journal Article In: Ophthalmology, vol. 121, no. 9, pp. 1827–1836, 2014. @article{Jayaramachandran2014, Objective: To perform the first randomized controlled trial comparing soft contact lens (SCL) with rigid gas-permeable lens (RGPL) wearing in infantile nystagmus (IN), using spectacle wear as a baseline. Design: Randomized, controlled cross-over trial with an intention-to-treat design. Participants and Controls: A total of 24 participants with IN (12 idiopathic, 12 with albinism). Methods: Participants were randomized into 1 of 2 treatment arms receiving the following sequence of treatments (2-3 weeks for each treatment): (A) spectacles, SCL, RGPL, and spectacle wear; or (B) spectacles, RGPL, SCL, and spectacle wear. Main Outcome Measures: The main outcome measure was mean intensity of nystagmus at the null region viewing at 1.2 m. Secondary outcome measures included the same measure at 0.4 m viewing and across the horizontal meridian (measured over a ±30° range at 3° intervals) for distance and near. The nystagmus foveation characteristics were similarly assessed over ±30° and at the null region at 1.2 m and 0.4 m viewing. Visual outcome measures included best-corrected visual acuity (BCVA) at 4 m and 0.4 m, gaze-dependent visual acuity (GDVA) (i.e., visual acuity when maintaining gaze angles over a ±30° range at 10° intervals) at 4 m, and reading performance at 0.4 m derived from the Radner reading chart. Results: There were no significant differences between SCL and RGPL wearing for any nystagmus characteristics or compared with spectacle wearing. The BCVA, reading acuity, and critical print size were significantly worse for SCL wearing compared with RGPL and baseline spectacle wear (P<0.05), although mean differences were less than 1 logarithm of the minimum angle of resolution (logMAR) line. Conclusions: Nystagmus was not significantly different during SCL and RGPL wearing in IN, and contact lens wearing does not significantly reduce nystagmus compared with baseline spectacle wearing. The wearing of SCL leads to a small but statistically significant deterioration in visual function compared with both RGPL and spectacle wearing at baseline, although mean effect sizes were not clinically relevant. |
Lisa N. Jefferies; Leon Gmeindl; Steven Yantis Attending to illusory differences in object size Journal Article In: Attention, Perception, and Psychophysics, vol. 76, no. 5, pp. 1393–1402, 2014. @article{Jefferies2014, Focused visual attention can be shifted between objects and locations (attentional orienting) or expanded and contracted in spatial extent (attentional focusing). Although orienting and focusing both modulate visual processing, they have been shown to be distinct, independent modes of attentional control. Objects play a central role in visual attention, and it is known that high-level object representations guide attentional orienting. It not known, however, whether attentional focusing is driven by low-level object representations (which code object size in terms of retinotopic extent) or by high-level representations (which code perceived size). We manipulated the perceived size of physically identical objects by using line drawings or photographs that induced the Ponzo illusion, in a task requiring the detection of a target within these objects. The distribution of attention was determined by the perceived size and not by the retinotopic size of an attended object, indicating that attentional focusing is guided by high-level object representations. |
Yu-Cin Jian; Hwa-Wei Ko Investigating the effects of background knowledge on Chinese word processing during text reading: Evidence from eye movements Journal Article In: Journal of Research in Reading, vol. 37, pp. S71–S86, 2014. @article{Jian2014a, This study investigates the effects of background knowledge on Chinese word processing during silent reading by monitoring adult readers' eye movements. Both higher knowledge (physics major) and lower knowledge (nonphysics major) graduate students were given physics texts to read. Higher knowledge readers spent less time rereading and had lower regression rates on unfamiliar physics words and common words in physics texts than did lower knowledge readers; they also had shorter gaze durations and fewer first-pass fixations on familiar physics words than on unfamiliar physics words. For unfamiliar physics words and common words, both groups predominantly fixated first on the beginnings of words when they made multiple fixations on a word and on a left-of-centre location when they fixated only once on a word. These findings suggest that both groups comprise mature readers with strong language concepts. However, differences in background knowledge led to different reading processes at different stages of reading. |
Yu-Cin Jian; Chao-Jung Wu; Jia-Han Su Learners' eye movements during construction of mechanical kinematic representations from static diagrams Journal Article In: Learning and Instruction, vol. 32, pp. 51–62, 2014. @article{Jian2014, We investigated the influence of numbered arrows on construction of mechanical kinematic representations by using static diagrams. Undergraduate participants viewed a two-stage diagram depicting a flushing cistern (with or without numbered arrows) and answered questions about its function, step-by-step. The arrow group demonstrated greater overall accuracy and made fewer errors on the measure of continuous relations than did the non-arrow group. The arrow group also spent more time looking at components relevant to the operational sequence and had longer first-pass fixation times and shorter saccade lengths. The non-arrow group made more saccades between the two diagrams. Analysis of transition probabilities indicated that both groups viewed components according to their continuous relations. The arrow group followed the numbered arrows whereas the unique pathway of the non-arrow group was to compare the two diagrams. These findings indicate that numbered arrows provide perceptual information but also facilitate cognitive processing. |
Zhenlan Jin; Scott N. J. Watamaniuk; Aarlenne Zein Khan; Elena Potapchuk; Stephen J. Heinen Motion integration for ocular pursuit does not hinder perceptual segregation of moving objects Journal Article In: Journal of Neuroscience, vol. 34, no. 17, pp. 5835–5841, 2014. @article{Jin2014, When confronted with a complex moving stimulus, the brain can integrate local element velocities to obtain a single motion signal, or segregate the elements to maintain awareness of their identities. The integrated motion signal can drive smooth-pursuit eye movements (Heinen and Watamaniuk, 1998), whereas the segregated signal guides attentive tracking of individual elements in multiple-object tracking tasks (MOT; Pylyshyn and Storm, 1988). It is evident that these processes can occur simultaneously, because we can effortlessly pursue ambulating creatures while inspecting disjoint moving features, such as arms and legs, but the underlying mechanism is unknown. Here, we provide evidence that separate neural circuits perform the mathematically opposed operations of integration and segregation, by demonstrating with a dual-task paradigm that the two processes do not share attentional resources. Human observers attentively tracked a subset of target elements composing a small MOT stimulus, while pursuing it ocularly as it translated across a computer display. Integration of the multidot stimulus yielded optimal pursuit. Importantly, performing MOT while pursuing the stimulus did not degrade performance on either task compared with when each was performed alone, indicating that they did not share attention. A control experiment showed that pursuit was not driven by integration of only the nontargets, leaving the MOT targets free for segregation. Nor was a predictive strategy used to pursue the stimulus, because sudden changes in its global velocity were accurately followed. The results suggest that separate neural mechanisms can simultaneously segregate and integrate the same motion signals. |
Kevin D. Johnston; Michael J. Koval; Stephen G. Lomber; Stefan Everling Macaque dorsolateral prefrontal cortex does not suppress saccade-related activity in the superior colliculus Journal Article In: Cerebral Cortex, vol. 24, no. 5, pp. 1373–1388, 2014. @article{Johnston2014, Of the many functions ascribed to the dorsolateral prefrontal cortex (DLPFC), the ability to override automatic stimulus-driven behavior is one of the most prominent. This ability has been investigated extensively with the antisaccade task, which requires suppression of saccades toward suddenly appearing visual stimuli. Convergent lines of evidence have supported a model in which the DLPFC suppresses unwanted saccades by inhibiting saccade-related activity in the ipsilateral superior colliculus (SC), a midbrain oculomotor structure. Here, we carried out a direct test of this inhibitory model using unilateral cryogenic deactivation of the DLPFC within the caudal principal sulcus (cPS) and simultaneous single-neuron recording of SC saccade-related neurons in monkeys performing saccades and antisaccades. Contrary to the inhibition model, which predicts that attenuation of inhibition effected by unilateral cPS deactivation should result in activity increases in ipsilateral and decreases in contralateral SC, we observed a delayed onset of saccade-related activity in the ipsilateral SC, and activity increases in the contralateral SC. These effects were mirrored by increased error rates of ipsiversive antisaccades, and reaction times of contraversive saccades. These data challenge the inhibitory model and suggest instead that the primary influence of the DLPFC on the SC is excitatory. |
Sven Hohenstein; Reinhold Klieg Semantic preview benefit during reading Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 40, no. 1, pp. 166–190, 2014. @article{Hohenstein2014, Word features in parafoveal vision influence eye movements during reading. The question of whether readers extract semantic information from parafoveal words was studied in 3 experiments by using a gaze-contingent display change technique. Subjects read German sentences containing 1 of several preview words that were replaced by a target word during the saccade to the preview (boundary paradigm). In the 1st experiment the preview word was semantically related or unrelated to the target. Fixation durations on the target were shorter for semantically related than unrelated previews, consistent with a semantic preview benefit. In the 2nd experiment, half the sentences were presented following the rules of German spelling (i.e., previews and targets were printed with an initial capital letter), and the other half were presented completely in lowercase. A semantic preview benefit was obtained under both conditions. In the 3rd experiment, we introduced 2 further preview conditions, an identical word and a pronounceable nonword, while also manipulating the text contrast. Whereas the contrast had negligible effects, fixation durations on the target were reliably different for all 4 types of preview. Semantic preview benefits were greater for pretarget fixations closer to the boundary (large preview space) and, although not as consistently, for long pretarget fixation durations (long preview time). The results constrain theoretical proposals about eye movement control in reading. |
Pawel Holas; Izabela Krejtz; Marzena Cypryańska; John B. Nezlek Orienting and maintenance of attention to threatening facial expressions in anxiety - An eye movement study Journal Article In: Psychiatry Research, vol. 220, no. 1-2, pp. 362–369, 2014. @article{Holas2014, Cognitive models posit that anxiety disorders stem in part from underlying attentional biases to threat. Consistent with this, studies have found that the attentional bias to threat-related stimuli is greater in high vs. low anxious individuals. Nevertheless, it is not clear if similar biases exist for different threatening emotions or for any facial emotional stimulus. In the present study, we used eye-tracking to measure orienting and maintenance of attention to faces displaying anger, fear and disgust as threats, and faces displaying happiness and sadness. Using a free viewing task, we examined differences between low and high trait anxious (HTA) individuals in the attention they paid to each of these emotional faces (paired with a neutral face). We found that initial orienting was faster for angry and happy faces, and high trait anxious participants were more vigilant to fearful and disgust faces. Our results for attentional maintenance were not consistent. The results of the present study suggest that attentional processes may be more emotion-specific than previously believed. Our results suggest that attentional processes for different threatening emotions may not be the same and that attentional processes for some negative and some positive emotions may be similar. |
Linbi Hong; Jennifer M. Walz; Paul Sajda Your eyes give you away: Prestimulus changes in pupil diameter correlate with poststimulus task-related EEG dynamics Journal Article In: PLoS ONE, vol. 9, no. 3, pp. e91321, 2014. @article{Hong2014, Pupillary measures have been linked to arousal and attention as well as activity in the brainstem's locus coeruleus norepinephrine (LC-NE) system. Similarly, there is evidence that evoked EEG responses, such as the P3, might have LC-NE activity as their basis. Since it is not feasible to record electrophysiological data directly from the LC in humans due to its location in the brainstem, an open question has been whether pupillary measures and EEG variability can be linked in a meaningful way to shed light on the nature of the LC-NE role in attention and arousal. We used an auditory oddball task with a data-driven approach to learn task-relevant projections of the EEG, for windows of data spanning the entire trial. We investigated linear and quadratic relationships between the evoked EEG along these projections and both prestimulus (baseline) and poststimulus (evoked dilation) pupil diameter measurements. We found that baseline pupil diameter correlates with early (175-200 ms) and late (350-400 ms) EEG component variability, suggesting a linear relationship between baseline (tonic) LC-NE activity and evoked EEG. We found no relationships between evoked EEG and evoked pupil dilation, which is often associated with evoked (phasic) LC activity. After regressing out reaction time (RT), the correlation between EEG variability and baseline pupil diameter remained, suggesting that such correlation is not explainable by RT variability. We also investigated the relationship between these pupil measures and prestimulus EEG alpha activity, which has been reported as a marker of attentional state, and found a negative linear relationship with evoked pupil dilation. In summary, our results demonstrate significant relationships between prestimulus and poststimulus neural and pupillary measures, and they provide further evidence for tight coupling between attentional state and evoked neural activity and for the role of cortical and subcortical networks underlying the process of target detection. |
Jörn M. Horschig; Ole Jensen; Martine R. Schouwenburg; Roshan Cools; Mathilde Bonnefond Alpha activity reflects individual abilities to adapt to the environment Journal Article In: NeuroImage, vol. 89, pp. 235–243, 2014. @article{Horschig2014, Recent findings suggest that oscillatory alpha activity (7-13. Hz) is associated with functional inhibition of sensory regions by filtering incoming information. Accordingly the alpha power in visual regions varies in anticipation of upcoming, predictable stimuli which has consequences for visual processing and subsequent behavior. In covert spatial attention studies it has been demonstrated that performance correlates with the adaptation of alpha power in response to explicit spatial cueing. However it remains unknown whether such an adaptation also occurs in response to implicit statistical properties of a task. In a covert attention switching paradigm, we here show evidence that individuals differ on how they adapt to implicit statistical properties of the task. Subjects whose behavioral performance reflects the implicit change in switch trial likelihood show strong adjustment of anticipatory alpha power lateralization. Most importantly, the stronger the behavioral adjustment to the switch trial likelihood was, the stronger the adjustment of anticipatory posterior alpha lateralization. We conclude that anticipatory spatial attention is reflected in the distribution of posterior alpha band power which is predictive of individual detection performance in response to the implicit statistical properties of the task. |
Dayana Hristova; Matej Guid; Ivan Bratko Assessing the difficulty of chess tactical problems Journal Article In: International Journal on Advances in Intelligent Systems, vol. 7, no. 3-4, pp. 728–738, 2014. @article{Hristova2014, We investigate experts' ability to assess the difficulty of a mental task for a human. The final aim is to find formalized measures of difficulty that could be used in automated assessment of the difficulty of a task. In experiments with tactical chess problems, the experts' estimations of difficulty are compared to the statistic-based difficulty ratings on the Chess Tempo website. In an eye tracking experiment, the subjects' solutions to chess problems and the moves that they considered are analyzed. Performance data (time and accuracy) are used as indicators of subjectively perceived difficulty. We also aim to identify the attributes of tactical positions that affect the difficulty of the problem. Understanding the connection between players' estimation of difficulty and the properties of the search trees of variations considered is essential, but not sufficient, for modeling the difficulty of tactical problems. Our findings include that (a) assessing difficulty is also very difficult for human experts, and (b) algorithms designed to estimate difficulty should interpret the complexity of a game tree in the light of knowledge-based patterns that human players are able to detect in a chess problem. |
S. Huber; Alon Mann; Hans-Christoph Nuerk; Korbinian Moeller Cognitive control in number magnitude processing: Evidence from eye-tracking Journal Article In: Psychological Research, vol. 78, no. 4, pp. 539–548, 2014. @article{Huber2014, The unit-decade compatibility effect describes longer response times and higher error rates for incompatible (e.g., 37_52) than compatible (e.g., 42_57) number comparisons. Recent research indicated that the effect depends on the percentage of same-decade filler items. In the present study, we further examined this relationship by recording participants' eye-fixation behaviour. In four conditions, participants had to compare item sets with different filler item types (i.e., same-decade and same-unit filler items) and different numbers of same-decade filler items (i.e., 25, 50, and 75 %). We found a weaker unit-decade compatibility effect with most fixations on tens in the condition with same-unit filler items. Moreover, the compatibility effect increased with the percentage of same-decade filler items which was accompanied by less fixations on tens and more fixations on units. Thus, our study provides first eye-tracking evidence for the influence of cognitive control in number processing. |
S. Huber; Korbinian Moeller; Hans-Christoph Nuerk Adaptive processing of fractions - Evidence from eye-tracking Journal Article In: Acta Psychologica, vol. 148, pp. 37–48, 2014. @article{Huber2014a, Recent evidence indicated that fraction pair type determined whether a particular fraction is processed holistically, componentially or in a hybrid manner. Going beyond previous studies, we investigated how participants adapt their processing of fractions not only to fraction type, but also to experimental context. To examine adaptation in fraction processing, we recorded participants' eye-fixation behaviour in a fraction magnitude comparison task.Participants' eye fixation behaviour indicated componential processing of fraction pairs with common components for which the decision-relevant components are easy to identify. Importantly, we observed that fraction processing was adapted to experimental context: Evidence for componential processing was stronger, when experimental context allowed valid expectations about which components are decision-relevant.Taken together, we conclude that fraction processing is adaptive beyond the comparison of different fraction types, because participants continuously adjust to the experimental context in which fractions are processed. |
Stefan Huber; Elise Klein; Klaus Willmes; Hans-Christoph Nuerk; Korbinian Moeller In: Frontiers in Human Neuroscience, vol. 8, pp. 172, 2014. @article{Huber2014b, Decimal fractions comply with the base-10 notational system of natural Arabic numbers. Nevertheless, recent research suggested that decimal fractions may be represented differently than natural numbers because two number processing effects (i.e., semantic interference and compatibility effects) differed in their size between decimal fractions and natural numbers. In the present study, we examined whether these differences indeed indicate that decimal fractions are represented differently from natural numbers. Therefore, we provided an alternative explanation for the semantic congruity effect, namely a string length congruity effect. Moreover, we suggest that the smaller compatibility effect for decimal fractions compared to natural numbers was driven by differences in processing strategy (sequential vs. parallel). To evaluate this claim, we manipulated the tenth and hundredth digits in a magnitude comparison task with participants' eye movements recorded, while the unit digits remained identical. In addition, we evaluated whether our empirical findings could be simulated by an extended version of our computational model originally developed to simulate magnitude comparisons of two-digit natural numbers. In the eye-tracking study, we found evidence that participants processed decimal fractions more sequentially than natural numbers because of the identical leading digit. Importantly, our model was able to account for the smaller compatibility effect found for decimal fractions. Moreover, string length congruity was an alternative account for the prolonged reaction times for incongruent decimal pairs. Consequently, we suggest that representations of natural numbers and decimal fractions do not differ. |
Lynn Huestegge; Iring Koch When two actions are easier than one: How inhibitory control demands affect response processing Journal Article In: Acta Psychologica, vol. 151, pp. 230–236, 2014. @article{Huestegge2014, Numerous studies showed that the simultaneous execution of multiple actions is associated with performance costs. Here, we demonstrate that when highly automatic responses are involved, performance in single-response conditions can actually be worse than in dual-response conditions. Participants responded to peripheral visual stimuli with an eye movement (saccade), a manual key press, or both. To manipulate saccade automaticity, a central fixation cross either remained present throughout the trial (overlap condition, lower automaticity) or disappeared 200. ms before visual target onset (gap condition, greater automaticity). Crucially, single-response conditions yielded more performance errors than dual-response conditions (i.e., dual-response benefit), especially in gap trials. This was due to difficulties associated with inhibiting saccades when only manual responses were required, suggesting that response inhibition (remaining fixated) can be even more resource-demanding than overt response execution (saccade to peripheral target). |
Lynn Huestegge; Aleksandra Pieczykolan; Iring Koch Talking while looking: On the encapsulation of output system representations Journal Article In: Cognitive Psychology, vol. 73, pp. 72–91, 2014. @article{Huestegge2014a, The idea that the human mind can be divided into distinct (but interacting) functional modules is an important presupposition in many theories of cognition. While previous research on modularity predominantly studied input domains (e.g., vision) or central processes, the present study focused on cognitive representations of output domains. Specifically, we asked to what extent output domain representations are encapsulated (i.e., immune to influence from other domains, representing a key feature of modularity) by studying determinants of interference between simultaneous action demands (oculomotor and vocal responses). To examine the degree of encapsulation, we compared single- vs. dual-response performance triggered by single stimuli. Experiment 1 addressed the role of stimulus modality under dimensionally overlapping response requirements (stimuli and responses were spatial and compatible throughout). In Experiment 2, we manipulated the presence of dimensional overlap across responses. Substantial performance costs associated with dual-response (vs. single-response) demands were observed across response modalities, conditions, and experiments. Dimensional overlap combined with shared spatial codes across responses enabled response-code priming (i.e., beneficial crosstalk between output domains). Overall, the results are at odds with the idea of strong encapsulation of output system representations and show how processing content determines the extent of interdependency between output domains in cognition. |
Stephanie Huette; Bodo Winter; Teenie Matlock; David H. Ardell; Michael J. Spivey Eye movements during listening reveal spontaneous grammatical processing Journal Article In: Frontiers in Psychology, vol. 5, pp. 410, 2014. @article{Huette2014, Recent research using eye-tracking typically relies on constrained visual contexts in particular goal-oriented contexts, viewing a small array of objects on a computer screen and performing some overt decision or identification. Eyetracking paradigms that use pictures as a measure of word or sentence comprehension are sometimes touted as ecologically invalid because pictures and explicit tasks are not always present during language comprehension. This study compared the comprehension of sentences with two different grammatical forms: the past progressive (e.g., was walking), which emphasizes the ongoing nature of actions, and the simple past (e.g., walked), which emphasizes the end-state of an action. The results showed that the distribution and timing of eye movements mirrors the underlying conceptual structure of this linguistic difference in the absence of any visual stimuli or task constraint: Fixations were shorter and saccades were more dispersed across the screen, as if thinking about more dynamic events when listening to the past progressive stories. Thus, eye movement data suggest that visual inputs or an explicit task are unnecessary to solicit analog representations of features such as movement, that could be a key perceptual component to grammatical comprehension. |
Heeju Hwang; Elsi Kaiser The role of the verb in grammatical function assignment in English and Korean Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 40, no. 5, pp. 1363–1376, 2014. @article{Hwang2014, One of the central questions in speech production is how speakers decide which entity to assign to which grammatical function. According to the lexical hypothesis (e. g., Bock & Levelt, 1994), verbs play a key role in this process (e. g., "send" and "receive" result in different entities being assigned to the subject position). In contrast, according to the structural hypothesis (e. g., Bock, Irwin, & Davidson, 2004), grammatical functions can be assigned based on a speaker's conceptual representation of an event, even before a particular verb is chosen. In order to examine the role of the verb in grammatical function assignment, we investigated whether English and Korean speakers exhibit semantic interference effects for verbs during a scene description task. We also analyzed speakers' eye movements during production. We found that English speakers exhibited verb interference effects and also fixated the action/verb region before the subject region. In contrast, Korean speakers did not show any verb interference effects and did not fixate the action/verb region before the subject region. Rather, in Korean, looks to the action/verb region sharply increased following looks to the object region. The findings provide evidence for the lexical hypothesis for English and are compatible with the structural hypothesis for Korean. We suggest that whether the verb is retrieved before speech onset depends on the role that the verb plays in grammatical function assignment or structural choice in a particular language. |
Afsheen Khan; Sally A. McFadden; Mark R. Harwood; Josh Wallman Salient distractors can induce saccade adaptation Journal Article In: Journal of Ophthalmology, vol. 2014, pp. 1–11, 2014. @article{Khan2014, When saccadic eye movements consistently fail to land on their intended target, saccade accuracy is maintained by gradually adapting the movement size of successive saccades. The proposed error signal for saccade adaptation has been based on the distance between where the eye lands and the visual target (retinal error). We studied whether the error signal could alternatively be based on the distance between the predicted and actual locus of attention after the saccade. Unlike conventional adaptation experiments that surreptitiously displace the target once a saccade is initiated towards it, we instead attempted to draw attention away from the target by briefly presenting salient distractor images on one side of the target after the saccade. To test whether less salient, more predictable distractors would induce less adaptation, we separately used fixed random noise distractors. We found that both visual attention distractors were able to induce a small degree of downward saccade adaptation but significantly more to the more salient distractors. As in conventional adaptation experiments, upward adaptation was less effective and salient distractors did not significantly increase amplitudes. We conclude that the locus of attention after the saccade can act as an error signal for saccade adaptation. |
Roozbeh Kiani; Leah Corthell; Michael N. Shadlen Choice certainty is informed by both evidence and decision time Journal Article In: Neuron, vol. 84, no. 6, pp. 1329–1342, 2014. @article{Kiani2014, "Degree of certainty" refers to the subjective belief, prior to feedback, that a decision is correct. A reliable estimate of certainty is essential for prediction, learning from mistakes, and planning subsequent actions when outcomes are not immediate. It is generally thought that certainty is informed by a neural representation of evidence at the time of a decision. Here we show that certainty is also informed by the time taken to form the decision. Human subjects reported simultaneously their choice and confidence about the direction of a noisy display of moving dots. Certainty was inversely correlated with reaction times and directly correlated with motion strength. Moreover, these correlations were preserved even for error responses, a finding that contradicts existing explanations of certainty based on signal detection theory. We also contrived a stimulus manipulation that led to longer decision times without affecting choice accuracy, thus demonstrating that deliberation time itself informs the estimate of certainty. We suggest that elapsed decision time informs certainty because it serves as a proxy for task difficulty. |
Sunjung Kim; Linda J. Lombardino; Wind Cowles; Lori J. Altmann Investigating graph comprehension in students with dyslexia: An eye tracking study Journal Article In: Research in Developmental Disabilities, vol. 35, no. 7, pp. 1609–1622, 2014. @article{Kim2014, The purpose of this study was to examine graph comprehension in college students with developmental dyslexia. We investigated how graph types (line, vertical bar, and horizontal bar graphs), graphic patterns (single and double graphic patterns), and question types (point locating and comparison questions) differentially affect graph comprehension of students with and without dyslexia. Groups were compared for (1) reaction times for answering comprehension questions based on graphed data and (2) eye gaze times for specific graph subregions (x-axis, y-axis, pattern, legend, question, and answer). Dyslexic readers were significantly slower in their graph comprehension than their peers with group differences becoming more robust with the increasing complexity of graphs and tasks. In addition, dyslexic readers' initial eye gaze viewing times for linguistic subregions (question and answer) and total viewing times for both linguistic (question and answer) and nonlinguistic (pattern) subregions were significantly longer than their control peers' times. In spite of using elementary-level paragraphs for comprehension and simple graph forms, young adults with dyslexia needed more time to process linguistic and nonlinguistic stimuli. These findings are discussed relative to theories proposed to address fundamental processing deficits in individuals with dyslexia. |
Matthew O. Kimble; Mariam Boxwala; Whitney Bean; Kristin Maletsky; Jessica Halper; Kaleigh Spollen; Kevin Fleming The impact of hypervigilance: Evidence for a forward feedback loop Journal Article In: Journal of Anxiety Disorders, vol. 28, no. 2, pp. 241–524, 2014. @article{Kimble2014, A number of prominent theories suggest that hypervigilance and attentional bias play a central role in anxiety disorders and PTSD. It is argued that hypervigilance may focus attention on potential threats and precipitate or maintain a forward feedback loop in which anxiety is increased. While there is considerable data to suggest that attentional bias exists, there is little evidence to suggest that it plays this proposed but critical role. This study investigated how manipulating hypervigilance would impact the forward feedback loop via self-reported anxiety, visual scanning, and pupil size. Seventy-one participants were assigned to either a hypervigilant, pleasant, or control condition while looking at a series of neutral pictures. Those in the hypervigilant condition had significantly more fixations than those in the other two groups. These fixations were more spread out and covered a greater percentage of the ambiguous scene. Pupil size was also significantly larger in the hypervigilant condition relative to the control condition. Thus the study provided support for the role of hypervigilance in increasing visual scanning and arousal even to neutral stimuli and even when there is no change in self-reported anxiety. Implications for the role this may play in perpetuating a forward feedback loop are discussed. |
Barrie P. Klein; Ben M. Harvey; Serge O. Dumoulin Attraction of position preference by spatial attention throughout human visual cortex Journal Article In: Neuron, vol. 84, no. 1, pp. 227–237, 2014. @article{Klein2014, Voluntary spatial attention concentrates neural resources at the attended location. Here, we examined the effects of spatial attention on spatial position selectivity in humans. We measured population receptive fields (pRFs) using high-field functional MRI (fMRI) (7T) while subjects performed an attention-demanding task at different locations. We show that spatial attention attracts pRF preferred positions across the entire visual field, not just at the attended location. This global change in pRF preferred positions systematically increases up the visual hierarchy. We model these pRF preferred position changes as an interaction between two components: an attention field and a pRF without the influence of attention. This computational model suggests that increasing effects of attention up the hierarchy result primarily from differences in pRF size and that the attention field is similar across the visual hierarchy. A similar attention field suggests that spatial attention transforms different neural response selectivities throughout the visual hierarchy in a similar manner. |
Elise Klein; S. Huber; Hans-Christoph Nuerk; Korbinian Moeller Operational momentum affects eye fixation behaviour Journal Article In: Quarterly Journal of Experimental Psychology, vol. 67, no. 8, pp. 1614–1625, 2014. @article{Klein2014a, The operational momentum effect (OM) indicates an association of mental addition with a rightward spatial bias, whereas subtraction is associated with a leftward bias. To evaluate the assumed attentional origin of the OM effect, we evaluated not only participants' relative estimation error in a task requiring them to locate addition and subtraction results on a given number line but also their eye-fixation behaviour. Furthermore, to investigate the situatedness of spatial-numerical associations, the orientation of the number line (left-to-right vs. right-to left) was manipulated. OM biases in participants' explicit number line estimations and more implicit eye-fixation behaviour are integrated into a two-process hypothesis of the OM effect suggesting a first rough spatial anticipation followed by an evaluation/correction process. This account not only is capable of accounting for the results observed for participants' relative estimation error but is also corroborated by the eye-fixation results. Importantly, the fact that all effects were found independent of the orientation of the number line indicates that spatial-numerical associations such as the OM effect may not be hard-wired associations of spatial and numerical representations but rather reflect influences of situatedness on numerical cognition. |
Guilhem Ibos; David J. Freedman Dynamic integration of task-relevant visual features in posterior parietal cortex Journal Article In: Neuron, vol. 83, no. 6, pp. 1468–1480, 2014. @article{Ibos2014, The primate visual system consists of multiple hierarchically organized cortical areas, each specialized for processing distinct aspects of the visual scene. For example, color and form are encoded in ventralpathway areas such as V4 and inferior temporal cortex, while motion is preferentially processed in dorsal pathway areas such as the middletemporal area. Such representations often need to be integrated perceptually to solve tasks that depend on multiple features. We tested the hypothesis that the lateral intraparietal area (LIP) integrates disparate task-relevant visual features by recording from LIP neurons in monkeys trained to identify target stimuli composed of conjunctionsof color and motion features. We show that LIP neurons exhibit integrative representations of both color and motion features when they are taskrelevant and task-dependent shifts of both direction and color tuning. This suggests that LIP plays a role in flexibly integrating task-relevant sensory signals. |
Joanne Ingram; Christopher J. Hand; Linda M. Moxey Processing inferences drawn from the logically equivalent frames half full and half empty Journal Article In: Journal of Cognitive Psychology, vol. 26, no. 7, pp. 799–817, 2014. @article{Ingram2014, Choice-based experiments indicate that readers draw sophisticated inferences from logically equivalent frames. Readers may infer that a glass was previously full if described as currently half empty, and previously empty if described as currently half full. The information leakage framework suggests these inferences are made because information about a previous state is leaked from speaker' s choice of frame. We examine if similar inferences are made during reading in two eye-tracking experiments. In Experiment 1, participants read a passage where a character describes a glass as currently half full or half empty before making a statement about the previous volume. We hypothesised that participants would infer that the glass was previously empty or full, respectively. Results suggest processing a previous volume of full is simpler regardless of the frame provided. In Experiment 2, materials were constructed to ensure inferences were based on participants' beliefs as opposed to characters'. Results support the information leakage framework; previous volumes of full and empty were processed more easily after current volumes of half empty and half full, respectively. We suggest that processing discrepancies between the two experiments are driven by word-related factors (e.g., markedness) or by participants' integration of characters' expectations. |
Albrecht W. Inhoff; Ralph Radach Parafoveal preview benefits during silent and oral reading: Testing the parafoveal information extraction hypothesis Journal Article In: Visual Cognition, vol. 22, no. 3-4, pp. 354–376, 2014. @article{Inhoff2014, The preview of a parafoveally visible word conveys benefits when it is subsequently fixated. The current study examined whether these benefits are determined by the effectiveness of parafoveal information extraction, as implied by current models of eye movement control during reading, or by the effectiveness with which extracted information is integrated when a previewed word is fixated. For this, the boundary technique was used to manipulate the extent to which parafoveal information could be extracted, and text was read silently or orally. Consistent with prior work, a parafoveal target word preview conveyed fewer benefits when less parafoveal information could be extracted, target viewing durations were longer during oral than during silent reading, and the two factors interacted in the target fixation data, with smaller preview benefits during oral than during silent reading. Survival analyses indicated that this occurred because parafoveal information use occurred at later point in time during oral reading. Diminished opportunity for parafoveal information extraction also diminished target skipping rate, and it resulted in smaller saccades to target words, but these effects were not influenced by reading mode. Parafoveally extracted information was thus used less effectively during oral reading only when it involved the integration of parafoveally extracted information during subsequent target viewing. The dissociation of extraction from integration challenges current models of eye movement control.$backslash$nThe preview of a parafoveally visible word conveys benefits when it is subsequently fixated. The current study examined whether these benefits are determined by the effectiveness of parafoveal information extraction, as implied by current models of eye movement control during reading, or by the effectiveness with which extracted information is integrated when a previewed word is fixated. For this, the boundary technique was used to manipulate the extent to which parafoveal information could be extracted, and text was read silently or orally. Consistent with prior work, a parafoveal target word preview conveyed fewer benefits when less parafoveal information could be extracted, target viewing durations were longer during oral than during silent reading, and the two factors interacted in the target fixation data, with smaller preview benefits during oral than during silent reading. Survival analyses indicated that this occurred because parafoveal information use occurred at later point in time during oral reading. Diminished opportunity for parafoveal information extraction also diminished target skipping rate, and it resulted in smaller saccades to target words, but these effects were not influenced by reading mode. Parafoveally extracted information was thus used less effectively during oral reading only when it involved the integration of parafoveally extracted information during subsequent target viewing. The dissociation of extraction from integration challenges current models of eye movement control. |
Kazuya Inoue; Yuji Takeda The properties of object representations constructed during visual search in natural scenes Journal Article In: Visual Cognition, vol. 22, no. 9-10, pp. 1135–1153, 2014. @article{Inoue2014, To investigate properties of object representations constructed during a visual search task, we manipulated the proportion of trials/task within a block: In a search-frequent block, 80% of trials were search tasks; remaining trials presented a memory task; in a memory-frequent block, this proportion was reversed. In the search task, participants searched for a toy car (Experiments 1 and 2) or a T-shape object (Experiment 3). In the memory task, participants had to memorize objects in a scene. Memory performance was worse in the search-frequent block than in the memory-frequent block in Experiments 1 and 3, but not in Experiment 2 (token change in Experiment 1; type change in Experiments 2 and 3). Experiment 4 demonstrated that lower performance in the search-frequent block was not due to eye-movement behaviour. Results suggest that object representations constructed during visual search are different from those constructed during memorization and they are modulated by type of target. |
David E. Irwin Short-term memory across eye blinks Journal Article In: Memory, vol. 22, no. 8, pp. 898–906, 2014. @article{Irwin2014, The effect of eye blinks on short-term memory was examined in two experiments. On each trial, participants viewed an initial display of coloured, oriented lines, then after a retention interval they viewed a test display that was either identical or different by one feature. Participants kept their eyes open throughout the retention interval on some blocks of trials, whereas on others they made a single eye blink. Accuracy was measured as a function of the number of items in the display to determine the capacity of short-term memory on blink and no-blink trials. In separate blocks of trials participants were instructed to remember colour only, orientation only, or both colour and orientation. Eye blinks reduced short-term memory capacity by approximately 0.6-0.8 items for both feature and conjunction stimuli. A third, control, experiment showed that a button press during the retention interval had no effect on short-term memory capacity, indicating that the effect of an eye blink was not due to general motoric dual-task interference. Eye blinks might instead reduce short-term memory capacity by interfering with attention-based rehearsal processes. |
David E. Irwin; Maria M. Robinson Perceiving stimulus displacements across saccades Journal Article In: Visual Cognition, vol. 22, no. 3, pp. 548–575, 2014. @article{Irwin2014a, The visual world appears stable despite frequent retinal image movements caused by saccades. Many theories of visual stability assume that extraretinal eye position information is used to spatially adjust perceived locations across saccades, whereas others have proposed that visual stability depends upon coding of the relative positions of objects. McConkie and Currie (1996) proposed a refined combination of these views (called the Saccade Target Object Theory) in which the perception of stability across saccades relies on a local evaluation process centred on the saccade target object rather than on a remapping of the entire scene, with some contribution from memory for the relative positions of objects as well. Three experiments investigated the saccade target object theory, along with an alternative hypothesis that proposes that multiple objects are updated across saccades, but with variable resolution, with the saccade target object (by virtue of being the focus of attention before the saccade and residing near the fovea after the saccade) having priority in the perception of displacement. Although support was found for the saccade target object theory in Experiment 1, the results of Experiments 2 and 3 found that multiple objects are updated across saccades and that their positions are evaluated to determine perceived stability. There is an advantage for detecting displacements of the saccade target, most likely because of visual acuity or attentional focus being better near the fovea, but it is not the saccade target alone that determines the perception of stability and of displacements across saccades. Rather, multiple sources of information appear to contribute. |