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Research Interests: Psychology, Computer Science, Perception, Localization, Motion perception, and 15 morePersistence, Medicine, Space perception, Vision, Humans, Models, Computer Simulation, Saccades, Eye, Psychological Models, Flash Photography, Saccade, Psychomotor Performance, Psychology and Cognitive Sciences, and Medical and Health Sciences
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model of the mechanism for the perceived location of a single
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... These predictions are compared with experimental results of a study with background visible just after a flash (Matin, Matin, Pola & Kowal, 1969), and the findings of a study with background disappearing at the time of a flash... more
... These predictions are compared with experimental results of a study with background visible just after a flash (Matin, Matin, Pola & Kowal, 1969), and the findings of a study with background disappearing at the time of a flash (Dassonville, Schlag & Schlag-Rey, 1995). ...
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Saccadic and smooth pursuit movements are among several eye movements that we make as we visually attend to objects in our environment. An important function of these two movements is to shift the direction of gaze (i.e., an imaginary... more
Saccadic and smooth pursuit movements are among several eye movements that we make as we visually attend to objects in our environment. An important function of these two movements is to shift the direction of gaze (i.e., an imaginary line directed outward from the central fovea) to clearly view an object of interest. Both movements are concerned with the horizontal-vertical coordinates of objects. This is in contrast to vergence movements that deal with the proximal location of objects (see Chapter 11: Models of Saccadic-Vergence Interactions). A saccade is a rapid movement, perhaps the fastest of skeletal muscle movements, that quickly takes our direction of gaze from an initial point in space to some other point or target. A smooth pursuit movement is a slow to medium velocity movement that allows us to visually follow a moving target, and thus maintain our gaze on or near the target. It is generally thought that the stimulus for a saccade is target position with respect to the fovea, whereas the stimulus for smooth pursuit is target velocity relative to the retina. Saccades can occur without pursuit, and vice versa, but in many circumstances, the two types of movement act conjointly. For example, during visual following of a target moving at moderate to high velocity, smooth pursuit is typically supplemented by saccades. These saccades quickly reduce target offset from the fovea that develops when pursuit velocity is less than target velocity.
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Research Interests: Motion perception, Vision, Humans, Female, Male, and 15 moreRetina, Exploration, Eye Movements, Middle Aged, Fixation, Adult, Time Factors, Neutralisation, Optokinetic Nystagmus, Neutralization, Visual Fixation, Random Allocation, photic stimulation, Psychology and Cognitive Sciences, and Medical and Health Sciences
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We have studied optokinetic responses to oscillating patterns of dots, and the suppression of these responses by a foveally stabilized target. Such a target suppressed most of the optokinetic response, although the target provided neither... more
We have studied optokinetic responses to oscillating patterns of dots, and the suppression of these responses by a foveally stabilized target. Such a target suppressed most of the optokinetic response, although the target provided neither retinal target motion ...
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It is generally believed that a target offset from the direction of gaze can only be fixated with a saccadic jump in eye position. By preventing saccadic eye movements from fixating a target, we have observed slow eye movements to both... more
It is generally believed that a target offset from the direction of gaze can only be fixated with a saccadic jump in eye position. By preventing saccadic eye movements from fixating a target, we have observed slow eye movements to both stationary and moving eccentric ...
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According to current accounts, the perceived location of a target flash presented in the dark around the time of a saccade comes largely from an extraretinal signal that begins to change before, and continues to change during and... more
According to current accounts, the perceived location of a target flash presented in the dark around the time of a saccade comes largely from an extraretinal signal that begins to change before, and continues to change during and following the saccade. Opposed to this view, this study offers a model suggesting that the perception of a single flash or two successive flashes in association with a saccade is the result of the combined effects of flash retinal signal persistence and an extraretinal signal that begins concurrent with or shortly after the saccade. For a single flash, the retinal signal persistence interacting with the extraretinal signal is responsible for the perceived location of the flash. In the case of two flashes with a short inter-flash-interval, the temporal overlap of the first flash persistence with the second flash persistence is a major factor in determining the perceived location of both of the flashes, and as a consequence, the perceived separation between them.
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... little or no trough, or a trough with little or no peak as in Figure 4. Such peaks and troughs are found as well in a substantial number of other studies concerned with mislocalization and compression (eg, Awater & Lappe, 2006;... more
... little or no trough, or a trough with little or no peak as in Figure 4. Such peaks and troughs are found as well in a substantial number of other studies concerned with mislocalization and compression (eg, Awater & Lappe, 2006; Ostendorf, Fischer, Finke & Ploner, 2007; Richard ...
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We explored the influence of changing size and blur on accommodation by presenting the two stimuli sinusoidally in counterphase. The frequency response of the accommodative system (0.05 to 1 Hz) was determined using a high-speed infrared... more
We explored the influence of changing size and blur on accommodation by presenting the two stimuli sinusoidally in counterphase. The frequency response of the accommodative system (0.05 to 1 Hz) was determined using a high-speed infrared optometer while the subject viewed the target in a Badal optometer. Blur was provided by moving the target dioptrically toward and away from the subject, and size of the target was altered by a variable aperture. Both stimuli were varied sinusoidally at the same frequency, but in counterphase. We find that both size and blur can have an influence on accommodation: blur is particularly powerful at low temporal frequencies, whereas size becomes effective at moderate and high temporal frequencies.