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https://www.readbyqxmd.com/read/28713304/eye-behavior-associated-with-internally-versus-externally-directed-cognition
#1
Mathias Benedek, Robert Stoiser, Sonja Walcher, Christof Körner
What do our eyes do when we are focused on internal representations such as during imagination or planning? Evidence from mind wandering research suggests that spontaneous shifts from externally directed cognition (EDC) to internally directed cognition (IDC) involves oculomotor changes indicative of visual disengagement. In the present study, we investigated potential differences in eye behavior between goal-directed forms of IDC and EDC. To this end, we manipulated the focus of attention (internal versus external) in two demanding cognitive tasks (anagram and sentence generation)...
2017: Frontiers in Psychology
https://www.readbyqxmd.com/read/28689088/looking-for-ideas-eye-behavior-during-goal-directed-internally-focused-cognition
#2
Sonja Walcher, Christof Körner, Mathias Benedek
Humans have a highly developed visual system, yet we spend a high proportion of our time awake ignoring the visual world and attending to our own thoughts. The present study examined eye movement characteristics of goal-directed internally focused cognition. Deliberate internally focused cognition was induced by an idea generation task. A letter-by-letter reading task served as external task. Idea generation (vs. reading) was associated with more and longer blinks and fewer microsaccades indicating an attenuation of visual input...
July 6, 2017: Consciousness and Cognition
https://www.readbyqxmd.com/read/28638094/microsaccades-are-sensitive-to-word-structure-a-novel-approach-to-study-language-processing
#3
Maya Yablonski, Uri Polat, Yoram S Bonneh, Michal Ben-Shachar
Microsaccades are miniature eye movements that occur involuntarily during fixation. They are typically inhibited following stimulus onset and are released from inhibition about 300 ms post-stimulus. Microsaccade-inhibition is modulated by low level features of visual stimuli, but it is currently unknown whether they are sensitive to higher level, abstract linguistic properties. To address this question, we measured the timing of microsaccades while subjects were presented with written Hebrew words and pronounceable nonwords (pseudowords)...
June 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28637052/subtle-eye-movement-metrics-reveal-task-relevant-representations-prior-to-visual-search
#4
Anouk M van Loon, Katya Olmos-Solis, Christian N L Olivers
Visual search is thought to be guided by an active visual working memory (VWM) representation of the task-relevant features, referred to as the search template. In three experiments using a probe technique, we investigated which eye movement metrics reveal which search template is activated prior to the search, and distinguish it from future relevant or no longer relevant VWM content. Participants memorized a target color for a subsequent search task, while being instructed to keep central fixation. Before the search display appeared, we briefly presented two task-irrelevant colored probe stimuli to the left and right from fixation, one of which could match the current target template...
June 1, 2017: Journal of Vision
https://www.readbyqxmd.com/read/28298299/time-compression-of-visual-perception-around-microsaccades
#5
Gongchen Yu, Mingpo Yang, Peng Yu, Michael C Dorris
Even during fixation, our eyes are in constant motion. For example, microsaccades are small (typically<1°) eye movements that occur 1~3 times/second. Despite their tiny and transient nature, our percept of visual space is compressed prior to microsaccades (Hafed 2013). As visual space and time are interconnected at both the physical and physiological levels, we asked whether microsaccades also affect the temporal aspects of visual perception. Here we demonstrate that the perceived interval between transient visual stimuli was compressed if accompanied by microsaccades...
March 15, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28278311/working-memory-load-modulates-microsaccadic-rate
#6
Mario Dalmaso, Luigi Castelli, Pietro Scatturin, Giovanni Galfano
Microsaccades are tiny eye movements that individuals perform unconsciously during fixation. Despite that the nature and the functions of microsaccades are still lively debated, recent evidence has shown an association between these micro eye movements and higher order cognitive processes. Here, in two experiments, we specifically focused on working memory and addressed whether differential memory load could be reflected in a modulation of microsaccade dynamics. In Experiment 1, participants memorized a numerical sequence composed of either two (low-load condition) or five digits (high-load condition), appearing at fixation...
March 1, 2017: Journal of Vision
https://www.readbyqxmd.com/read/28254651/how-microsaccades-relate-to-lateralized-erp-components-of-spatial-attention-a-co-registration-study
#7
Susann Meyberg, Werner Sommer, Olaf Dimigen
Covert shifts of attention that follow the presentation of a cue are associated with lateralized components in the event-related potential (ERP): the "early directing attention negativity" (EDAN) and the "anterior directing attention negativity" (ADAN). Traditionally, these shifts are thought to take place while gaze is fixated and, thus, in the absence of saccades. However, microsaccades of small amplitude (<1°) occur frequently and involuntarily also during fixation and are closely correlated with spatial attention...
February 28, 2017: Neuropsychologia
https://www.readbyqxmd.com/read/28242738/neuronal-control-of-fixation-and-fixational-eye-movements
#8
REVIEW
Richard J Krauzlis, Laurent Goffart, Ziad M Hafed
Ocular fixation is a dynamic process that is actively controlled by many of the same brain structures involved in the control of eye movements, including the superior colliculus, cerebellum and reticular formation. In this article, we review several aspects of this active control. First, the decision to move the eyes not only depends on target-related signals from the peripheral visual field, but also on signals from the currently fixated target at the fovea, and involves mechanisms that are shared between saccades and smooth pursuit...
April 19, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28242737/unchanging-visions-the-effects-and-limitations-of-ocular-stillness
#9
REVIEW
Susana Martinez-Conde, Stephen L Macknik
Scientists have pondered the perceptual effects of ocular motion, and those of its counterpart, ocular stillness, for over 200 years. The unremitting 'trembling of the eye' that occurs even during gaze fixation was first noted by Jurin in 1738. In 1794, Erasmus Darwin documented that gaze fixation produces perceptual fading, a phenomenon rediscovered in 1804 by Ignaz Paul Vital Troxler. Studies in the twentieth century established that Jurin's 'eye trembling' consisted of three main types of 'fixational' eye movements, now called microsaccades (or fixational saccades), drifts and tremor...
April 19, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28202573/alteration-of-the-microsaccadic-velocity-amplitude-main-sequence-relationship-after-visual-transients-implications-for-models-of-saccade-control
#10
Antimo Buonocore, Chih-Yang Chen, Xiaoguang Tian, Saad Idrees, Thomas A Münch, Ziad M Hafed
Microsaccades occur during gaze fixation to correct for miniscule foveal motor errors. The mechanisms governing such fine oculomotor control are still not fully understood. In this study, we explored microsaccade control by analyzing the impacts of transient visual stimuli on these movements' kinematics. We found that such kinematics can be altered in systematic ways depending on the timing and spatial geometry of visual transients relative to the movement goals. In two male rhesus macaques, we presented peripheral or foveal visual transients during an otherwise stable period of fixation...
May 1, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28163059/revising-the-link-between-microsaccades-and-the-spatial-cueing-of-voluntary-attention
#11
Susann Meyberg, Petra Sinn, Ralf Engbert, Werner Sommer
Microsaccades - i.e., small fixational saccades generated in the superior colliculus (SC) - have been linked to spatial attention. While maintaining fixation, voluntary shifts of covert attention toward peripheral targets result in a sequence of attention-aligned and attention-opposing microsaccades. In most previous studies the direction of the voluntary shift is signaled by a spatial cue (e.g., a leftwards pointing arrow) that presents the most informative part of the cue (e.g., the arrowhead) in the to-be attended visual field...
February 17, 2017: Vision Research
https://www.readbyqxmd.com/read/28114483/bayesian-microsaccade-detection
#12
Andra Mihali, Bas van Opheusden, Wei Ji Ma
Microsaccades are high-velocity fixational eye movements, with special roles in perception and cognition. The default microsaccade detection method is to determine when the smoothed eye velocity exceeds a threshold. We have developed a new method, Bayesian microsaccade detection (BMD), which performs inference based on a simple statistical model of eye positions. In this model, a hidden state variable changes between drift and microsaccade states at random times. The eye position is a biased random walk with different velocity distributions for each state...
January 1, 2017: Journal of Vision
https://www.readbyqxmd.com/read/28044023/how-is-visual-salience-computed-in-the-brain-insights-from-behaviour-neurobiology-and-modelling
#13
REVIEW
Richard Veale, Ziad M Hafed, Masatoshi Yoshida
Inherent in visual scene analysis is a bottleneck associated with the need to sequentially sample locations with foveating eye movements. The concept of a 'saliency map' topographically encoding stimulus conspicuity over the visual scene has proven to be an efficient predictor of eye movements. Our work reviews insights into the neurobiological implementation of visual salience computation. We start by summarizing the role that different visual brain areas play in salience computation, whether at the level of feature analysis for bottom-up salience or at the level of goal-directed priority maps for output behaviour...
February 19, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/27956580/visual-discomfort-from-flash-afterimages-of-riloid-patterns
#14
Louise O'Hare
Op-art-based stimuli have been shown to be uncomfortable, possibly due to a combination of fixational eye movements (microsaccades) and excessive cortical responses. Efforts have been made to measure illusory phenomena arising from these stimuli in the absence of microsaccades, but there has been no attempt thus far to decouple the effects of the cortical response from the effect of fixational eye movements. This study uses flash afterimages to stabilise the image on the retina and thus reduce the systematic effect of eye movements, in order to investigate the role of the brain in discomfort from op-art-based stimuli...
December 11, 2016: Perception
https://www.readbyqxmd.com/read/27891684/changes-in-visibility-as-a-function-of-spatial-frequency-and-microsaccade-occurrence
#15
Francisco M Costela, Michael B McCamy, Mary Coffelt, Jorge Otero-Millan, Stephen L Macknik, Susana Martinez-Conde
Fixational eye movements (FEMs), including microsaccades, drift, and tremor, shift our eye position during ocular fixation, producing retinal motion that is thought to help visibility by counteracting neural adaptation to unchanging stimulation. Yet, how each FEM type influences this process is still debated. Recent studies found little to no relationship between microsaccades and visual perception of spatial frequencies (SF). However, these conclusions were based on coarse analyses that make it hard to appreciate the actual effects of microsaccades on target visibility as a function of SF...
November 27, 2016: European Journal of Neuroscience
https://www.readbyqxmd.com/read/27876511/modulation-of-microsaccades-by-spatial-frequency-during-object-categorization
#16
Matt Craddock, Frank Oppermann, Matthias M Müller, Jasna Martinovic
The organization of visual processing into a coarse-to-fine information processing based on the spatial frequency properties of the input forms an important facet of the object recognition process. During visual object categorization tasks, microsaccades occur frequently. One potential functional role of these eye movements is to resolve high spatial frequency information. To assess this hypothesis, we examined the rate, amplitude and speed of microsaccades in an object categorization task in which participants viewed object and non-object images and classified them as showing either natural objects, man-made objects or non-objects...
January 2017: Vision Research
https://www.readbyqxmd.com/read/27836729/discovering-recurring-patterns-in-electrophysiological-recordings
#17
Bart Gips, Ali Bahramisharif, Eric Lowet, Mark J Roberts, Peter de Weerd, Ole Jensen, Jan van der Eerden
BACKGROUND: Fourier-based techniques are used abundantly in the analysis of electrophysiological data. However, these techniques are of limited value when the signal of interest is non-sinusoidal or non-periodic. NEW METHOD: We present sliding window matching (SWM): a new data-driven method for discovering recurring temporal patterns in electrophysiological data. SWM is effective in detecting recurring but unknown patterns even when they appear non-periodically...
January 1, 2017: Journal of Neuroscience Methods
https://www.readbyqxmd.com/read/27739541/spatiotemporal-properties-of-microsaccades-model-predictions-and-experimental-tests
#18
Jian-Fang Zhou, Wu-Jie Yuan, Zhao Zhou
Microsaccades are involuntary and very small eye movements during fixation. Recently, the microsaccade-related neural dynamics have been extensively investigated both in experiments and by constructing neural network models. Experimentally, microsaccades also exhibit many behavioral properties. It's well known that the behavior properties imply the underlying neural dynamical mechanisms, and so are determined by neural dynamics. The behavioral properties resulted from neural responses to microsaccades, however, are not yet understood and are rarely studied theoretically...
October 14, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27509130/a-causal-role-for-the-cortical-frontal-eye-fields-in-microsaccade-deployment
#19
Tyler R Peel, Ziad M Hafed, Suryadeep Dash, Stephen G Lomber, Brian D Corneil
Microsaccades aid vision by helping to strategically sample visual scenes. Despite the importance of these small eye movements, no cortical area has ever been implicated in their generation. Here, we used unilateral and bilateral reversible inactivation of the frontal eye fields (FEF) to identify a cortical drive for microsaccades. Unexpectedly, FEF inactivation altered microsaccade metrics and kinematics. Such inactivation also impaired microsaccade deployment following peripheral cue onset, regardless of cue side or inactivation configuration...
August 2016: PLoS Biology
https://www.readbyqxmd.com/read/27446709/automated-motion-correction-using-parallel-strip-registration-for-wide-field-en-face-oct-angiogram
#20
Pengxiao Zang, Gangjun Liu, Miao Zhang, Changlei Dongye, Jie Wang, Alex D Pechauer, Thomas S Hwang, David J Wilson, David Huang, Dengwang Li, Yali Jia
We propose an innovative registration method to correct motion artifacts for wide-field optical coherence tomography angiography (OCTA) acquired by ultrahigh-speed swept-source OCT (>200 kHz A-scan rate). Considering that the number of A-scans along the fast axis is much higher than the number of positions along slow axis in the wide-field OCTA scan, a non-orthogonal scheme is introduced. Two en face angiograms in the vertical priority (2 y-fast) are divided into microsaccade-free parallel strips. A gross registration based on large vessels and a fine registration based on small vessels are sequentially applied to register parallel strips into a composite image...
July 1, 2016: Biomedical Optics Express
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