Showing papers on "Eye tracking published in 1979"

Is visual information integrated across successive fixations in reading

Abstract: College students read a passage presented in AlTeRnAtInG cAsE on a CRT while their eye movements were monitored. During certain saccades, the case of every letter was changed (a became A, B became b). This change was not perceived and had no effect on eye movements. Apparently visual features of the type which specify the difference between upper- and lowercase letters are not integrated across fixations during reading.

Pilot helmet mounted CIG display with eye coupled area of interest

Abstract: A system that uses the computer more efficiently in computer generated image displays by allocating priority status to the area being viewed by the observer while progressively diminishing the resolution requirements of the displayed scene toward its perimeter. The video signal corresponds to the orientation of the observer's head which is ascertained by head and eye trackers, and provides a variable level of detail that tends to match the visual acuity of the human eye.

Eye Tracking and Psychopathology: New Procedures Applied to a Sample of Normal Monozygotic Twins

Abstract: • New methods for examining eye movements were developed and applied in a study of young, adult monozygotic twins. Subjects, tested twice, engaged in smooth pursuit tracking at different target frequencies, followed a stimulus requiring saccadic eye movements, performed a related psychomotor hand tracking task, and tracked a target while monitoring changes in the stimulus display. Analysis of test-retest reliability and twin concordance suggested that performance on these tasks characterized stable traits and were consistent with other reports implicating a genetic contribution to tracking ability. Special consideration was given to the probable role of attention in producing various types of tracking deficit. Estimates of the incidence of tracking dysfunction and correlations with psychometrically measured personality traits were examined.

Electro-oculographic Recording and Scoring of Smooth Pursuit and Saccadic Eye Tracking: A Parametric Study Using Monozygotic Twins

Abstract: Following reports that psychiatric patients and their relatives produced deviant oculomotion, new procedural and quantitative methods were developed and applied in a parametric study of tracking proficiency in 32 monozygotic twin pairs tested twice. Subjects tracked a spot of light across an oscilloscope screen. The target was driven sinusoidally at various frequencies for smooth pursuit tracking and by a modified square wave generator for saccadic tracking. Also included were a smooth pursuit test requiring subjects to “monitor” the aperiodic appearance of a hole in the center of the oscillating target and a psychomotor test requiring subjects to manually center a dot in a moving circle. For pursuit tracking, the electro-oculogram (EOG) and target motion were fed to a computer programmed to calculate root-mean-square differences between EOG and target channels. The saccadic EOG was computer-analyzed by measuring movement latencies. Performance on the various tasks was analyzed with emphasis on the effects of the monitor requirement, which dramatically reduced tracking error. Measures of retest reliability and twin concordance suggested that observed individual differences in performance on these tasks represent stable traits.

Toward the use of eye movements in the study of language processing

Abstract: Three problems in the use of eye movement data for the study of language processing are discussed: the perceptual span problem, the data summary problem, and the eye‐mind lag problem. Recent research on perception during reading is described which bears on these problems. Finally, a general approach to the use of eye movement data for studying language processing is presented, based on present knowledge of perceptual processing and eye movement control during reading.

Types of saccadic eye movements

Abstract: The term saccade is applied to a variety of eye movements, including saccadic refixations, microsaccades, fast phases of nystagmus, and fast phases of other ocular oscillations. Numerous clinical and theoretical descriptions of saccades have resulted in a proliferation of named saccadic subtypes and clinical syndromes; these include purely descriptive phrases and those meant to imply physiology or pathophysiology. Among such terms are hypometric saccades, dysmetric saccades, glissadic eye movements, slow saccades, overlapping saccades, dynamic overshoots, closely spaced saccades, andpulseless saccades (figure 1). From the analysis of quantitative eye movement recordings of normal individuals and patients with neurologic diseases, and from the results of computer simulations, one may describe saccadic eye movement subtypes based on the responsible neurologic control signals. This description provides a logical framework for clinical observations which we hope will be useful during neurologic examinations. The organization of figure 1 is based on the underlying neural controller signals. The controller signal has two components: the pulse that moves the eye rapidly from one point to the next, and the step that holds the eye in the new p0sition.l The pulse is composed of a high-frequency burst of motoneuron activity for the agonist and a concomitant pulse of inhibi t ion, a pause i n motoneuron firing, for the antagonist. The step is composed of step changes in the steady state motoneuron firing rates: a step increase for the agonist and a step decrease for the antagonist. Inhibition of the antagonist is as important as excitation of the agonist for attaining highvelocity saccades.2 When both the pulse and the step are the correct size for the desired refixation change, there is a normometric saccade, an entirely accurate singlestep refixation. When both the pulse and the step are not the correct size, a dysmetric refixation eye movement results. A common type of saccadic undershoot is the single-step, hypometric saccadic refixation. If the step portion of the motoneuron saccadic controller signal is correct, but the pulse portion of the controller signal is too small due to an error, then the dynamic saccade (the initial fast portion of the saccadic eye movement) falls short of the desired position, and the saccadic refixation is completed with a glissadic eye movement. A glissadic eye movement is a gliding or sliding eye movement which gradually approaches the target po~i t ion.~ This includes any eye movement configuration resulting from a mismatching of the pulse and step components of the controller signal.” Saccadic refixations with glissades have been recorded from patients with internuclear ophthalmoplegia, abducens palsy, and myasthenia gravis, and from fatigued normals. A variation of this type of hypometric saccade, with very low velocity, could result from a controller signal with no pulse at all. The resultant eye movements have been referred to as %low,” or “pulseless” saccades and include the eye movements described in spinocerebellar degenerat i~n,~ progressive supranuclear palsy,6 and extraocular muscle paralysis.2 These slow or pulseless saccades are the extreme case of glissadic undershoot, and have velocities similar to vergence eye movements. Single-step, hypermetric saccadic refixations (those which overshoot the target with the dynamic saccade) may have either dynamic overshoot or glissadic overshoot. Normal human saccades often have dynamic over~hoot.~ Monkeys also exhibit dynamic overshoot, but this has been studied only for small saccades.8 Glissadic overshoot is caused by a mismatch between the pulse and step components of the controller ~ i g n a l . ~ When the step is correct and the pulse is too big, the error is probably created by a pulse of too long a d u r a t i ~ n . ~ Multiple-step dysmetric saccadic refixations are composed of two or more dynamic saccadic compo-

The Control of Eye Movements in Reading (Tutorial Paper)

Abstract: The first part of this paper reviews recent data on how the characteristics of eye movements in reading depend on three classes of experimental variables: those related to the reader (age, reading skill); those related to the material being read (overall appearance, difficulty, word length); and a third class, the attitude of the reader toward the text (search versus comprehension). In the second part, a distinction is made between global eye movement measures (average over a number of lines of text), and local ones (measures made for a single position on text). Local measures are of interest because of the psycholinguists hope that they will reflect ongoing sentence processing. For this hope to be realistic, it must be shown that the eye movement control mechanisms are sufficiently rapid to allow the eye’s course to be adjusted immediately on the basis of the information being gathered at every instant. The evidence presently available shows the possibility of immediate control of fixation duration, and “almost immediate” control of saccade size. Reading is a basic and constant occupation for most people. We are bombarded by written material, words pop out of posters and signs and, even if we try to avoid them, our eyes seem driven to read them.

Double Purkinje eye tracker

Abstract: An eye tracker measures the point in space on which the eye is fixated. An input mirror reflects an input image into the eye and directs the Purkinje images so formed in the eye back into the eye tracker mechanism. The images are gathered by a collimating objective and directed through focusing and deflecting optics so as to be incident on light flux measuring devices (photodetectors). The optics and detectors are connected in closed loop servo systems which keep the first and fourth Purkinje images centered on their respective photodetectors, keep the input beam properly positioned in the eye, and at the same time generate signals responsive to movement of the first Purkinje image to give a measure of both translational and rotational horizontal and vertical eye movement and movement of the fourth Purkinje image to give a measure of purely horizontal and vertical eye movement. Circuitry combines the signals to generate a measure of purely translational horizontal and vertical signals. The first Purkinje image is also directed to be focused nominally at a given focal distance. Light flux measuring devices are positioned equal distances before and behind the given focal distance, whereby the output signal from the devices provides a measure of focus and axial position of the eye and the difference in output signals is used in a servo system to drive the collimating objective, thereby to focus the first Purkinje image at the given focal distance.

The computer and eye processing pictures: The implementation of a raster graphics device

Abstract: The process of solving visual analogies was examined using a digital video display and video-based eye tracker. The results indicated that increasing the complexity of an analogy by increasing the number of relations involved in the problem resulted primarily in increasing the time it takes to discover the mapping between the two members of the first pair. The display of the picture and the analysis of the eye fixations are described.

Eye Movements in Reading: Eye Guidance and Integration

Abstract: Eye guidance in reading and control of fixation durations are discussed and relevant data reviewed. It is concluded that the location of fixations in reading is determined in a nonrandom manner and that fixation durations are affected by cognitive activities occurring during the fixation. Recent experiments on the integration of information across successive saccades are described. These experiments suggest that I) eye movements per se are not necessary for integration since similar patterns of results were obtained when subjects made eye movements and when the saccade was simulated; 2) attentional allocation is tied to the direction of an eye movement; and 2) purely visual information obtained from parafoveal vision is not overlapped with visual information in foveal vision after the saccade. On the basis of the data and experiments reviewed, a tentative processmonitoring view of eye movements in reading is proposed. Saccadic eye movements during reading generally extend about 8 character spaces (or 2 deg of visual angle), while the mean duration of the fixational pauses separating each saccade is 200–250 msec. However, there is a great deal of variability in both these eye movement characteristics so that the range of saccades is often 1 to 20 character spaces and the mean fixation duration is from 100 to over 500 msec (Rayner & McConkie, 1976). Recently, there have been a large number of studies utilizing eye movement data as dependent variables in attempts to understand the reading process (see Rayner, 1978a, for a review.)

Monocular asymmetries in recognition after an eye movement: sighting dominance and dextrality

Abstract: Although monocular recognition scores for targets presented immediately after an eye movement do not differ, the two eyes show marked recognition asymmetries when both eyes are receiving inputs but a specific target is only presented to one. In general, the right eye performs better than the left, although there are interactions with sighting dominance and the direction of eye movement.

An Investigation of Eye Gaze and Its Relation to Selected Verbal Behavior

Abstract: Eye gaze avoidance is examined in relation to the occurrence of turn-taking, vocalized pauses, sentence changes, repetitions, “you know,”“like,” sentence fragments, simple sentences, and complex sentences. The results provide support for the hypothesis that people avoid eye gaze when experiencing difficulty in encoding. This finding is discussed in relation to previous research and possible implications for the study of interpersonal communication.

A comparison of kinesthetic-tactual and visual displays via a critical tracking task.

Abstract: The feasibility of using the critical tracking task to evaluate kinesthetic-tactual displays was examined. The test subjects were asked to control a first-order unstable system with a continuously decreasing time constant by using either visual or tactual unidimensional displays. The results indicate that the critical tracking task is both a feasible and a reliable methodology for assessing tactual tracking. Further, that the critical tracking methodology is as sensitive and valid a measure of tactual tracking as visual tracking is demonstrated by the approximately equal effects of quickening for the tactual and visual displays.

Field independence, lateralization and defensive style.

Abstract: This study investigated the relationship between field independence and defense clustering as measured by the Defense Mechanisms Inventory and lateral eye movements. Subjects had previously been classified either as hysterical or obsessive style by the Rorschach and WAIS Comprehension subtest. Previous findings indicate that these subjects have a preferred direction of lateral eye movement in a questioning format (hysterical style = left; obsessive style = right). This study found no relationship between field independence and defense clustering and lateral eye movements. To the extent that eye gaze indexes hemispheric activation, we conclude that neither field independence nor defense clustering was related to hemispheric lateralization.

Eye movements and cognitive psychology: On-line computer approaches to studying visual information processing

Abstract: Advantages of using on-line computers to record eye movement data are discussed. These advantages include computer scoring of eye movement data, greater accuracy in identifying the location of a fixation, greater accuracy in determining timing variables such as saccade duration and fixation duration, and the capability of controlling stimulus presentation as a function of eye location. Emphasis is placed on the latter of these advantages. The characteristics of an on-line eye movement recording system are briefly described, followed by a description of the research using such a system to investigate reading, integration of information across eye movements, eccentric vision, and picture processing and visual search.

Human eye tracking as a sequential input adaptive process

Abstract: Sequential input adaptive system theory is applied to human eye tracking of targets with one-dimensional dimensional motion defined by sine functions, sums of sine functions and triangle functions. The sequential theory describes the mean eye tracking movements of two subjects for these inputs. The theory is predictive for irregular inputs in that when its parameters for a subject are identified and adjusted for a reference input, it then predicts mean eye tracking behavior for that subject for inputs of comparable complexity.

A head-mounted scene holder for eye movement research

Abstract: An inexpensive head-mounted scene holder is described. In contrast to the usual biteboard/fixed-head approach, the present apparatus allows head movements without introducing substantial artifact. This enables eye movement investigations of brain-damaged or psychiatric subjects who often cannot maintain prolonged head immobility; also, the unit makes possible subjects’ verbal reports coincident with visual scanning.

Visual Field Plotting Using Eye Movement Response

Abstract: Traditional techniques for visual field plotting are described as acting in opposition to the underlying perceptual task. An approach is described which encourages the natural eye movement response and objectively classifies it as either an acquisition or a search response. Empirical results demonstrate the reliability of eye movement response as an index of perception of peripheral stimuli A visual field plotting example is given and implications for clinical practice are discussed.