Showing papers on "Eye tracking published in 1997"

Spontaneous eye movements during visual imagery reflect the content of the visual scene

Abstract: In nine naive subjects eye movements were recorded while subjects viewed and visualized four irregularly-checkered diagrams. Scanpaths, defined as repetitive sequences of fixations and saccades were found during visual imagery and viewing. Positions of fixations were distributed according to the spatial arrangement of subfeatures in the diagrams. For a particular imagined diagrammatic picture, eye movements were closely correlated with the eye movements recorded while viewing the same picture. Thus eye movements during imagery are not random but reflect the content of the visualized scene. The question is discussed whether scanpath eye movements play a significant functional role in the process of visual imagery.

Method of and apparatus for viewing an image

Abstract: Light from an image displayed on a display screen (10) is transmitted to an observer's eye (11) by way of a dynamic optical element (12) (such as a spatial light modulator or an electrically switchable holographic composite) which acts as a lens. Emitters (17) on the display screen (10) emit infrared radiation which is projected by the dynamic lens (12) as a broad wash onto the eye (11). Infrared radiation reflected back from the eye (11) is focused by the dynamic lens (12) onto detectors (18) also provided on the display screen (10). The detectors (18) are thus able to sense the direction of eye gaze, and the dynamic lens (12) is controlled in dependence on this to create an area of high resolution in an area of interest centred on the direction of gaze, which is moved to follow the eye gaze as its direction alters. Other than in the area of interest, the dynamic lens (12) has a relatively low resolution.

Eye Tracking, Attention, and Schizotypal Symptoms in Nonpsychotic Relatives of Patients With Schizophrenia

Abstract: Background: Biological relatives of patients with schizophrenia demonstrate an increased prevalence of schizotypal personality disorder symptoms, eye tracking deficits, and attentional disturbances. We investigated whether these hypothesized components of a schizophrenia-related phenotype are associated with one another or are independent in nonpsychotic relatives of patients with schizophrenia. Methods: Eighty-three nonpsychotic first-degree relatives of 38 patients with schizophrenia and 45 control subjects without a psychiatric diagnosis underwent clinical evaluation, eye tracking evaluation, and the Continuous Performance Test (CPT) of visual attention. Results: Eye tracking qualitative rating was more powerful than quantitative eye tracking measures or CPT measures in discriminating relatives of patients with schizophrenia from control subjects. Correlations between neurocognitive variables and DSM-III-R schizotypal personality disorder symptom clusters suggested that CPT errors of omission are associated with positive schizotypal symptoms. Eye tracking measures were not significantly correlated with schizotypal symptoms or CPT errors in relatives of patients with schizophrenia. Conclusions: Eye tracking deficits in the relatives of patients with schizophrenia are unrelated to CPT deficits and schizotypal symptoms. Eye tracking deficits and disturbances in visual attention may be separate components of a schizophrenia-related phenotype and should be considered as independent factors in genetic studies of schizophrenia.

Understanding Eye Movements in Reading.

Abstract: The primary characteristics of eye movements during reading are reviewed and 4 areas are summarized: (a) the span of effective vision, (b) integration of information across eye movements, (c) the decision of where to fixation next, and (d) the decision of when to move the eyes. In addition, some current controversies about eye movements and reading are discussed.

Eye-tracking dysfunction in offspring from the New York High-Risk Project: diagnostic specificity and the role of attention.

Abstract: Eye tracking abnormalities were studied in the offspring of schizophrenic, unipolar depressed and bipolar probands from the New York High-Risk Project to examine their familial specificity. Offspring of schizophrenic and depressed probands both had significant global performance deficits based on spectral purity measurements, but only the offspring of schizophrenic probands had an increased rate of intrusive anticipatory saccades. The greater specificity of high anticipatory saccade rate than global performance impairment suggests that this eye movement abnormality may provide a more specific biological marker of risk for schizophrenia than the global measure of eye tracking performance used in this study. Attention facilitation effectively normalized all performance deficits in the offspring of schizophrenic patients, suggesting that a problem sustaining focused visual attention may contribute to eye tracking deficits observed in the relatives of schizophrenic probands.

Saccades without eye movements

Abstract: When reading text, human subjects use a pattern of eye movements consisting of fast saccadic movements and fixations1. We have found a subject who cannot make eye movements. Her visual perception is surprisingly normal and she is able to read at high speeds. She uses movements of the head to compensate for the absence of eye movements. Her head movements during reading have a saccadic character and show many of the features that characterize eye movements.

Eye detection system for providing eye gaze tracking

Abstract: An eye detection system comprises a source, such as an infrared laser diodes for emitting a divergent beam of infrared radiation. A spatial light modulator is controlled so as to act as a deflector for scanning the beam. A detector detects radiation which is retro-reflected by the eye back along the path of the scanning beam. The deflection angle of the SLM and, for a position sensitive detector, the location of the center of illumination on the detector can be used to determine the angle to the center of the pupil of the eye. By subsequently detecting the angle to the glints corresponding to other sources and, the gaze position of the eye on a screen can be determined.

Manuo-ocular coordination in target tracking. I. A model simulating human performance

Abstract: During eye tracking of a self-moved target, human subjects' performance differs from eye-alone tracking of an external target. Typical latency between target and eye motion onsets is shorter, ocular smooth pursuit (SP) saturation velocity increases and the maximum target motion frequency at which the SP system functions correctly is higher. Based on a previous qualitative model, a quantitative model of the coordination control between the arm motor system and the SP system is presented and evaluated here. The model structure maintains a high level of parallelism with the physiological system. It contains three main parts: the eye motor control (containing a SP branch and a saccadic branch), the arm motor control and the coordination control. The coordination control is achieved via an exchange of information between the arm and the eye sensorimotor systems, mediated by sensory signals (vision, proprioception) and motor command copy. This cross-talk results in improved SP system performance. The model has been computer simulated and the results have been compared with human subjects' behavior observed during previous experiments. The model performance is seen to quantitatively fit data on human subjects.

An empirical study of attending and comprehending multimedia presentations

Abstract: The paper reports two studies concerning attention to and comprehension of Multimedia presentations. The MM sequence used was taken from a commercially produced CD-ROM, ‘The Etiology of Cancer’. First, an eye tracking study of the presentation is reported. A second study was then cortductekl ml the memorisation of the materials used in the eye tracking study. The results of the studies are used to propose guidelines to improve design of MM presentations.

The Eye Mouse, an eye communication device

Abstract: The Eye Mouse is a communication aid designed for the severely disabled. Specifically, it provides the user with a means to control an ordinary PC mouse with a combination of eye movements and blinks. By constantly monitoring the electrooculogram signal (EOG) of the user, the Eye Mouse (EM) is able to recognize several intentional eye motions and in turn, control a cursor on the PC screen.

Eye Movements in Visual Cognition: A Computational Study

Abstract: Visual cognition depends critically on the moment-to-moment orientation of gaze. Gaze is changed by saccades, rapid eye movements that orient the fovea over targets of interest in a visual scene. Saccades are ballistic; a prespecified target location is computed prior to the movement and visual feedback is precluded. Once a target is fixated, gaze is typically held for about 300 milliseconds, although it can be held for both longer and shorter intervals. Despite these distinctive properties, there has been no specific computational model of the gaze targeting strategy employed by the human visual system during visual cognitive tasks. This paper proposes such a model that uses iconic scene representations derived from oriented spatiochromatic filters at multiple scales. Visual search for a target object proceeds in a coarse-to-fine fashion with the target''s largest scale filter responses being compared first. Task-relevant target locations are represented as saliency maps which are used to program eye movements. Once fixated, targets are remembered by using spatial memory in the form of object-centered maps. The model was empirically tested by comparing its performance with actual eye movement data from human subjects in natural visual search tasks. Experimental results indicate excellent agreement between eye movements predicted by the model and those recorded from human subjects.

Image processing for improved eye-tracking accuracy.

Abstract: Video cameras provide a simple, noninvasive method for monitoring a subject's eye movements. An important concept is that of the resolution of the system, which is the smallest eye movement that can be reliably detected. While hardware systems are available that estimate direction of gaze in real-time from a video image of the pupil, such systems must limit image processing to attain real-time performance and are limited to a resolution of about 10 arc minutes. Two ways to improve resolution are discussed. The first is to improve the image processing algorithms that are used to derive an estimate. Off-line analysis of the data can improve resolution by at least one order of magnitude for images of the pupil. A second avenue by which to improve resolution is to increase the optical gain of the imaging setup (i.e., the amount of image motion produced by a given eye rotation). Ophthalmoscopic imaging of retinal blood vessels provides increased optical gain and improved immunity to small head movements but requires a highly sensitive camera. The large number of images involved in a typical experiment imposes great demands on the storage, handling, and processing of data. A major bottleneck had been the real-time digitization and storage of large amounts of video imagery, but recent developments in video compression hardware have made this problem tractable at a reasonable cost. Images of both the retina and the pupil can be analyzed successfully using a basic toolbox of image-processing routines (filtering, correlation, thresholding, etc.), which are, for the most part, well suited to implementation on vectorizing supercomputers.

A quantitative analysis of smooth pursuit eye tracking in monozygotic twins discordant for schizophrenia.

Abstract: Background: Previous studies of discordant monozygotic (MZ) twins have suggested that abnormal smooth pursuit eye tracking is an indicator of genetic liability for schizophrenia. We attempted to replicate this in a different sample of twins. Methods: Probands from 12 sets of MZ twins discordant for schizophrenia who met DSM-III-R criteria for schizophrenia or schizoaffective disorder and their cotwins without psychiatric diagnosis (except 2 with a history of substance abuse) and 12 sets of normal control MZ twins. Psychiatric diagnosis was based on Structured Clinical Interview; monozygosity was based on analysis of 19 red blood cell antigens. Smooth pursuit eye movement gain (equal to the ratio of eye-target velocity) and numbers, amplitudes, and subtypes of saccadic eye movements were compared. Measures were derived from computer analysis of digitized infrared oculographic recordings of constant velocity (16.67%o per second) smooth pursuit eye tracking. Results: Quantitative measures of eye tracking for the affected twin were inferior to those of the unaffected co-twin, with affected twins showing significant decreases in gain and significant increases in numbers and amplitudes of total and intrusive saccades. Moreover, whereas means for the group of affected twins differed significantly from those of normal controls on measures of gain and total saccades, means for the group of unaffected co-twins were well within the normal range. Conclusions: These data are consistent with the hypothesis that abnormal eye tracking is associated with the expression of illness, or phenotype, in schizophrenia, at least in this twin sample. The data raise questions regarding the use of eye tracking measurement for identifying putative gene carriers among at-risk relatives in genetic linkage studies of schizophrenia.

An Eye Tracking System for Analysis of Pilots' Scan Paths.

Abstract: : Portable eye movement and automated analysis systems have been developed for use in pilot training and other applications where it is necessary to monitor and analyze changes in an observer's point of regard. The eye movement system hardware consists of a lightweight, head-mounted, two-dimensional eye tracker and miniature scene camera, an electronic control and processing unit, and a video recorder and monitor. This system, manufactured by El Mar, Inc., is easily transportable and weighs less than 10 Kg. During training, a small crosshair indicating the point of regard is electronically combined with video from the scene camera and both are recorded on video tape for later analysis by an integrated image processing system. The automated analysis system determines which objects were viewed, how long each was viewed, and the order in which they were viewed. The present systems were used to measure and analyze the visual scan paths of pilots in three aircraft simulators. This was done to determine whether data of this kind can be used to increase training effectiveness by identifying efficient scanning strategies and by quantifying differences in the behavior of expert and novice pilots. Scan paths were evaluated for: (a) T-37 instructor pilots (IPs) and T-37 student IPs (rated pilots training to be IPs) while they performed precision instrument approaches in a motion base simulator, (b) F-16 IPs while performing air-to-air scenarios in the Air Combat Engagement Simulator (ACES) and (c) F-16 LANTIRN IPs while performing low-level scenarios in the LANTIRN simulator. The results of these evaluations are described.

A Neural Network Approach to Tracking Eye Position

Abstract: The design of a neural network based eye tracker is presented. A series of experiments with counterpropagation neural networks convert synthetic video images into eye coordinates by an enhanced feed-forward neural network with multiple winning hidden layer nodes. Difficulties encountered during the design process are discussed. The results show that accurate, fine-grained tracking of a human's eye position is possible by processing the video image collected from a goggle-mounted miniature charge-coupled device (CCD) camera.

Eye Movement Contingent Display Control: Personal Reflections and Comments.

Abstract: This article provides a personal account of the development of the Eye Movement Contingent Display Control research methodology for the study of perceptual and cognitive processes in reading.

Method and apparatus for evaluating and mapping visual field

Abstract: A method for examining a visual field of a subject includes the steps of stimulating the subject eye movement reflex to an off field visual stimulus and mapping the subject visual field based on a positive reflex to the stimulus. An apparatus (20) for evaluating the visual field of a subject (22) includes a subject affixation mechanism (24) for affixing a portion of the apparatus (20) to the subject (22), an eye tracking mechanism (26) operatively connected to the subject affixation means (24) for tracking eye movement of the subject (22), and visual field stimulus generater (28) operatively connected to the affixation mechanism (24) for generating a visual stimulus.

Speed and accuracy of eye-gaze pointing.

Abstract: The current experiment examined the speed-accuracy trade-off of saccadic movement between two targets. Ten subjects looked alternately at two targets as fast and as accurately as possible for 2 min. under different conditions of target size, distance between targets, and direction of eye movement. Saccadic movement of the left eye was tracked and recorded with an infrared eye monitoring device to compute the starting position, ending position, and duration of each saccadic movement. Eye-movement time was significantly related to target size and distance between targets, but the speed-accuracy trade-off was significantly different from that predicted by Fitts' Law. Reaction time was not significantly changed by the direction of eye movement.

Digital virtual chiasm for controlled stimulation of visual cortices

Abstract: A digital virtual chiasm apparatus for controlled stimulation of visual cortices, which contains an eye tracker, a digital computer, and a display device. The apparatus is capable of generating a first set of stimuli in a first half visual field while simultaneously generating a second set of stimuli in second, contralateral half visual field and a boundary between said first half visual field and said second half visual field. It is also capable of moving the boundary between the first half visual field and the second half visual field in response to eye movement of the subject.

A Foveated Visual Tracking Chip

Abstract: This chip uses both biological motivation and compact focal-plane processing to solve a real commercial problem such as 2D camera pointing. This system is unique in its use of a spatially variant layout and arbitration between smooth pursuit (in fovea) and acquisition (in periphery) to improve the tracking process (similar to primate visual tracking). Furthermore, with the exception of the motor drivers, little additional circuitry is required for successful visual tracking.

Eye Tracking in Tactical Decision Making Environments: Implications for Decision Support Evaluation *

Abstract: This paper discusses the use of eye movement monitoring systems in evaluating visual displays to support tactical decision making. A variety of analytic approaches are considered from a conceptual and practical standpoint and applied to preliminary data collected using the TADMUS DSS display. Eye movement data were collected using a head-mounted eye tracking system worn by command-level decision makers (Commanding and Tactical Action Officers) in tactical scenarios using a decision support system in a simulation of an Aegis cruiser Combat Information Center. While results are preliminary and not definitive, prospects for the use of eye movement monitoring systems as tools for evaluating decision support displays are considered good.

Eye Movement Analysis and its Application to Evaluation of Image Quality

Abstract: It is well known that an image has a particular gazing area. From the experimental results of our previous papers, we found that total image quality is highly influenced by quality of the gazing area. In this paper, we evaluated total image quality of degraded images by a physical quality criterion (PQC) calculated from the gazing area. The experimental result showed that the calculated PQC is not dependent on the scene. On the other hand, PQC calculated from the whole area of the image is dependent on the scene content. In this paper, the effectiveness of the evaluation of image quality under the consideration of gazing area is presented and discussed.

Perceptually-driven Avatars and Interfaces: active methods for direct control

Abstract: We show how machine perception techniques can allow people to use their own bodies to control complex virtual representations in computer graphic worlds. In contrast to existing solutions for motion capture, tracking people for virtual avatars or intelligent interfaces requires processing at multiple levels of resolution. We apply active perception techniques and use visual attention to track a user’s pose or gesture at several scales simultaneously. We also develop an active speech interface that leverages this visual tracking ability; by electronically focusing a microphone array towards a particular user, speech recognition in acoustically cluttered environments is possible. Together, these methods allow virtual representations of people to be based on their actual expression, tracking their body and face gestures and speech utterances as they freely move about a room without attached wires, microphones, or other sensors.

Document classification system

Abstract: An image system with an imaging device obtains and presents at least one image. An eye gaze system associated with the imaging device determines a non-closed loop portion of the at least one image that an eye of a viewer observes. The image system associates the at least one image with the non-closed loop portion of the at least one image. An image processor analyzes the image based at least in part on the image itself together with data representative of the gaze information to determine the content of the image, where the gaze information is a non-closed loop portion of the image that an eye of a viewer observes. The image system associates the content with the image.

Single mirror tracking system for free-head video-based eye-gaze detection method

Abstract: The single rotation mirror system was designed for the development of the free-head video-based eye-gaze detection device used on communicators for the physically disadvantaged. In a previous study, the camera with the zoom lens rotated to direct its shooting area toward the eye. However, a better tracking system using a single mirror was expected. In the present study, the mirror was rotated two-dimensionally by a pair of servomotors through the lever crank mechanism. The image rotation owing to the mirror was compensated. The response of the mirror rotation system was much better than that of the camera rotation system. The eye-gaze point was determined from the eye position in space and the eye-gaze direction relative to the camera axis. The eye position was estimated using the mirror angle and the distance from the mirror rotation center to the eye, which was measured by the ultrasonic distance meter. The eye-gaze direction was estimated using the relative positions between the pupil and corneal reflection images, which were obtained using the real time image processor. Eye-gaze detection was extremely precise under the head-fixed conditions. Under the head-unfixed condition, however, the improvement of the ultrasonic distance meter or the arrangement of the mirror and menu screen relative to the head was expected.