Spatiotemporal Characteristics of Visual Localization.
Annual technical rept. 1 Jun 82-31 May 83,
SRI INTERNATIONAL MENLO PARK CA
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A computer-based display system has been designed and built enabling the investigation of the processes underlying spatial localization. Among the results obtained in the past year with the use of this device are a Eye movements play a significant role in spatial localization that is not limited to positioning the stimulus array optimally on the retina. b Neither retinal image drift nor abrupt movement of the retinal image is sufficient to restore normal performance on a localization task when the effects of eye movements on retinal image position are eliminated. c Preliminary data indicate that localization is a very slow process, much slower than form detection. In related work it has been shown that for some simple forms sine wave gratings the relative orientation of the stimuli does not affect ability to detect small differences in their sizes and conversely a difference in size between two stimuli does not affect ability to detect a small difference in their orientations. Further it has been found that the detection of small differences in size between two objects is masked strongly by stimuli consisting of fine lines but not by stimuli consisting of broader lines high and low spatial frequency gratings respectively. It has also been found that eye movements are essential to the discrimination of objects on the basis of hue except in the yellow region of the spectrum.