225 Works

Covert Attention Tracking: Towards Two-Dimensional Real-Time Recordings

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Achieving attention tracking as easily as recording eye movements is still beyond reach. However, by exploiting Steady-State Visual Evoked Potentials (SSVEPs) we could recently record in a satisfactory way the horizontal trajectory of covert visuospatial attention in single trials, both when attending target motion and during mental motion extrapolation. Here we show that, despite the different cortical functional architecture for horizontal and vertical motion processing, the same result is obtained for vertical attention tracking. Thus,...

Direction Estimation Model for Gaze Controlled Systems

Pawanesh Abrol &
Detection of gaze requires estimation of the position and the relation between user’s pupil and glint. This position is mapped into the region of interest using different edge detectors by detecting the glint coordinates and further gaze direction. In this research paper, a Gaze Direction Estimation (GDE) model has been proposed for the comparative analysis of two standard edge detectors Canny and Sobel for estimating automatic detection of the glint, its coordinates and subsequently the...

Examining the validity of the total dwell time of eye fixations to identify landmarks in a building

Alain De Wulf, , , & Philippe De Maeyer
It is uncertain to what extent the duration of eye fixations reflects the use of landmarks during navigation. Therefore, a study was conducted in which eye tracking data and route descriptions were collected of 23 participants who were highly familiar with the indoor test environment. Based on the total fixation time on different landmark categories, two measures were calculated, namely the calculated landmark category use and the probable landmark category use. Based on the ratio...

Performance of a simple remote video-based eye tracker with GPU acceleration

Jean-Pierre Du Plessis &
Eye tracking is a well-established tool that is often utilised in research. There are currently many different types of eye trackers available, but they are either expensive, or provide a relatively low sampling frequency. The eye tracker presented in this paper was developed in an effort to address the lack of low-cost high-speed eye trackers. It utilises the Graphical Processing Unit (GPU) in an attempt to parallelise aspects of the process to localize feature points...

User-Friendly Locations of Error Messages in Web Forms: An Eye Tracking Study

Error messages presented to users are one of the most important elements of Web forms. Error messages are embedded in different parts of the forms available on the Internet and presented in various formats. One of the measures of a user-friendly error message design is the ability to easily capture users’ attention and facilitate fast error correction. In this empirical study, I tested four different locations of error messages frequently used in Web forms on...

Learning to search. The importance of eye movements in the decrease of response times during a visual choice reaction time task

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Reaction times are often used as an indicator of the efficiency of the processes in thecentral nervous system. While extensive research has been conducted on the possibleresponse time correlates, the role of eye movements in visual tasks is yet unclear. Here wereport data to support the role of eye movements during visual choice reaction time training.Participant performance, reaction times, and total session duration improved. Eyemovementsshowed expected changes in saccade amplitude and resulted in improvementin visual...

Eye-tracking Deaf and hearing viewing of sign language interpreted news broadcasts

In this study, the viewing habits of deaf and hearing adults are investigated using eye tracking while they watched interpreted news broadcasts. The study shows that deaf viewers primarily focus on the interpreter and secondarily access picture material, but make very little use of subtitles or lip-reading. In contrast, hearing viewers prioritise pictorial content but also spend significant proportions of time examining subtitles, lip-reading and even watching the interpreter. Viewing patterns are dependent on pictorial...

The influence of emotional picture thematic content on exploratory eye movements

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In picture viewing, emotional vs. neutral stimuli could play a different role in eye movement parameters and in the spatial progression of the scanpath. The aim of this paper is to investigate exploratory behaviour of normal subjects during the vision of emotional vs. non-emotional stimuli, by considering to what extent the thematic content (animate vs. inanimate) is likely to influence the observer’s eye movements. Sixty-five subjects’ eye movement patterns were measured while looking to emotional...

Conditional co-occurrence probability acts like frequency in predicting fixation durations

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The predictability of an upcoming word has been found to be a useful predictor in eye movement research, but is expensive to collect and subjective in nature. It would be desirable to have other predictors that are easier to collect and objective in nature if these predictors were capable of capturing the information stored in predictability. This paper contributes to this discussion by testing a possible predictor: conditional co-occurrence probability. This measure is a simple...

Correction of Saccade-Induced Midline Errors in Responses to Pure Disparity Vergence Stimuli.

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Purely symmetrical vergence stimuli aligned along the midline (cyclopean axis) require only a pure vergence response. Yet, in most responses saccades are observed and these saccades must either produce an error in the desired midline response or correct an error produced by asymmetry in the vergence response. A previous study (Semmlow, et al. 2008) has shown that the first saccade to appear in a response to a pure vergence stimulus usually increased the deviation from...

Semantic Override of Low-level Features in Image Viewing – Both Initially and Overall

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Guidance of eye-movements in image viewing is believed to be controlled by stimulus driven factors as well as viewer dependent higher level factors such as task and memory. It is currently debated what proportions these factors contribute to gaze guidance, and also how they vary over time after image onset. Overall, the unanimity regarding these issues is surprisingly low and there are results supporting both types of factors as being dominant in eye-movement control under...

Visual Fixation Durations and Saccade Amplitudes: Shifting Relationship in a Variety of Conditions

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Is there any relationship between visual fixation durations and saccade amplitudes in free exploration of pictures and scenes? In four experiments with naturalistic stimuli, we compared eye movements during early and late phases of scene perception. Influences of repeated presentation of similar stimuli (Experiment 1), object density (Experiment 2), emotional stimuli (Experiment 3) and mood induction (Experiment 4) were examined. The results demonstrate a systematic increase in the durations of fixations and a decrease for...

A statistical mixture method to reveal bottom-up and top-down factors guiding the eye-movements

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When people gaze at real scenes, their visual attention is driven both by a set of bottom-up processes coming from the signal properties of the scene and also from top-down effects such as the task, the affective state, prior knowledge, or the semantic context. The context of this study is an assessment of manufactured objects (here car cab interior). From this dedicated context, this work describes a set of methods to analyze the eye-movements during...

The effect of a temporary absence of target velocity information on visual tracking

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Experiments with the Rashbass ‘step-ramp’ paradigm have revealed that the initial catchup saccade that occurs near pursuit onset uses target velocity as well as position information in its programming. Information about both position and motion also influences smooth pursuit. To investigate the timing of velocity sampling near the initiation of saccades and smooth pursuit, we analyzed the eye movements made in nine ‘step-ramp’ conditions, produced by combining –2, 0 and +2 deg steps with –8,...

Heterophoria: Vergence stability and visual acuity after asymmetric saccades

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Many patients with heterophoria report on symptoms related to impaired vision. To investigate whether these symptoms are provoked by saccades this study examines whether in heterophoria effects on intrasaccadic and postsaccadic vergence movements are linked to effects on visual performance. Visual acuity was measured in 35 healthy subjects during fixation and immediately after asymmetric diverging saccades. Binocular position traces were recorded by video-oculography. Subjects with exophoria showed larger intrasaccadic divergence amplitudes, which in turn led...

Vergence tracking: a tool to assess oculomotor performance in stereoscopic displays

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Oculomotor conflict induced between the accommodative and vergence components in stereoscopic displays represents an unnatural viewing condition. There is now some evidence that stereoscopic viewing may induce discomfort and changes in oculomotor parameters. The present study sought to measure oculomotor performance during stereoscopic viewing. Using a 3D stereo setup and an eye-tracker, vergence responses were measured during 20-min exposure to a virtual visual target oscillating in depth, which participants had to track. The results showed...

“Trait” and “state” aspects of fixation disparity during reading

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In our study, 14 subjects read 60 sentences from the Potsdam Sentence Corpus twice (viewing distance: 60 cm), while eye movements were measured with the EyeLink II. We analyzed fixation disparities for complete sentence replications (N=388). After subtracting the average fixation disparity of each sentence from each observation (which gave the “state” fixation disparity), 99% of all remaining fixation disparities were aligned, i.e. smaller than one character width (20 min arc) – depending mostly on...

Influences of dwell time and cursor control on the performance in gaze driven typing

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In gaze controlled computer interfaces the dwell time is often used as selection criterion. But this solution comes along with several problems, especially in the temporal domain: Eye movement studies on scene perception could demonstrate that fixations of different durations serve different purposes and should therefore be differentiated. The use of dwell time for selection implies the need to distinguish intentional selections from merely per-ceptual processes, described as the Midas touch problem. Moreover, the feedback...

Task-relevant spatialized auditory cues enhance attention orientation and peripheral target detection in natural scenes

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Concurrent auditory stimuli have been shown to enhance detection of abstract visual targets in experimental setups with little ecological validity. We presented 11 participants, wearing an eye-tracking device, with a visual detection task in an immersive audiovisual environment replicating a real-world environment. The participants were to fixate on a visual target and to press a key when they were confident of having detected the target. The visual world was accompanied by a task-relevant or task-irrelevant...

Eye-tracking multi-word units: some methodological questions

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Eye-tracking in linguistics has focused mainly on reading at the level of the word or sentence. In this paper we discuss how the phenomenon of formulaic language might best be examined using this methodology. Formulaic language is fundamentally multi-word in nature, therefore an approach to eye-tracking that considers the “word” as the basic unit of analysis may require re-evaluation. We review the existing literature on single word and sentence processing, and also those studies that...

Abstracts of the 17th European Conference on Eye Movements 2013

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This document contains all abstracts of the 17th European Conference on Eye Movements, August 11-16 2013 in Lund, Sweden ECEM 2013 has been the 17th European Conference on Eye Movements, with the original aims ‘to exchange information on current research, equipment and software’ remaining at the forefront. ECEM is transdisciplinary, promoting new approaches, co-operation between research fields and communication between researchers. It has grown from it’s origins as a small, specialist conference to a large...

Anticipation of physical causality guides eye movements

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Causality is a unique feature of human perception. We present here a behavioral investigation of the influence of physical causality during visual pursuit of object collisions. Pursuit and saccadic eye movements of human subjects were recorded during ocular pursuit of two concurrently launched targets, one that moved according to the laws of Newtonian mechanics (the causal target) and the other one that moved in a physically implausible direction (the non-causal target). We found that anticipation...

Comparison of shutter glasses and mirror stereoscope for measuring dynamic and static vergence

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Vergence eye movement recordings in response to disparity step stimuli require to present different stimuli to the two eyes. The traditional method is a mirror stereoscope. Shutter glasses are more convenient, but have disadvantages as limited repetition rate, residual cross task, and reduced luminance. Therefore, we compared both techniques measuring (1) dynamic disparity step responses for stimuli of 1 and 3 deg and (2) fixation disparity, the static vergence error. Shutter glasses and mirror stereoscope...

Evidence for a Structural Analysis of Target Selection in Picture Viewing

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Spontaneous fixations onto shapes are driven by a structural analysis. But is such analysis also carried out during free viewing of real-world scenes? Here, we analyze how fixation locations in such scenes are related to their region using the region's symmetric axes as a reference. Each fixation location is compared with respect to its nearest symmetric-axis segment by a latitude and a longitude measure. Analyzing the distributions for the two measures we find that there...

Haptic feedback in eye typing

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Proper feedback is essential in gaze based interfaces, where the same modality is used for both perception and control. We measured how vibrotactile feedback, a form of haptic feedback, compares with the commonly used visual and auditory feedback in eye typing. Haptic feedback was found to produce results that are close to those of auditory feedback; both were easy to perceive and participants liked both the auditory ”click” and the tactile “tap” of the selected...

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