PubMed · 14166055
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
J HOCHBERG, R HELD. 1964. NONVISUAL COMPONENTS IN VISUAL FORM PERCEPTION.. https://doi.org/10.2466/pms.1964.18.2.559
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
Physiological studies of non-human primates have suggested that the direction of gaze can modulate the gain of neuronal responses to visual stimuli in many cortical areas including V1. The neural gaze modulation is suggested to subserve the conversion from gaze-independent (eye-centered) to dependent (e.g., head-centered) representations. However, it has not been established whether the gaze modulation has significant influences on human visual perception. Here we show that gaze direction modestly but significantly modulates the magnitudes of the motion aftereffect, the tilt aftereffect and the size aftereffect. These aftereffects were stronger when the adaptation and test patterns were presented in the same gaze direction, than when they were presented in different gaze directions, even though the patterns always stimulated the same retinal location. The gaze modulation effect was not statistically significant for the post-adaptation elevation of contrast detection thresholds. The gaze modulation of visual aftereffects provides a useful psychophysical tool to analyze human cortical processes for coordinate transformations of visual space.
We conducted three experiments to examine the effect of spatial arrangement of test stimulus on the motion aftereffect (MAE). The adaptation and test stimuli were presented to subjects successively. Each adaptation stimulus consisted of a set of three gratings; a central stationary grating was located between the two surrounding gratings, one above and the other below respectively, which were arranged to move leftward for two minutes. The location and/or the shape of the test stimulus were varied to examine the effects of the spatial arrangement. The first and second experiments revealed that the MAE lasted longer when the surrounding gratings for the test were superimposed on those for the adaptation than when they were not superimposed. Further, the results of both experiments showed that the duration was not affected by the distance between the central grating and surrounding one. The results of the third experiment showed that the MAE lasted longer when the central grating for the test was identical with that for the adaptation than when not, and that the surrounding for the test need not to be identical with that for the adaptation. These results support Wade's hypothesis for explaining how MAE occurs.
Two sets of experiments demonstrate new properties of motion in orientational after-effects. In a previous report, we showed that when observers adapted to a static bar grating whose elements varied in size or intensity from one side to the other, offset of the grating resulted in a motion after-effect, with the perceived motion in the direction of the largest or most intense bar. In the first new experiment, we show that similar results can be produced by varying the duration of the bar elements, with the direction of the motion after-effect toward the bar with the longest duration. In the second new experiment we demonstrate that the perceived speed of the motion after-effect is influenced by the spatial extent of the after-effect, with larger extents corresponding to faster speeds. The experimental findings are discussed in the context of a neural network theory of visual perception. In this theory, a moving oriented contour leaves a trail of activity among cortical cells tuned to orthogonal orientations. We hypothesize that the grating stimuli produce after-effects that mimic the pattern of oriented responses produced by a true moving contour, and the visual system interprets this pattern as a cue for motion. We also show how the model connects the properties of these motion after-effects to properties of visual persistence.