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Abstract:
Abstract: Afterimages are one type of a large class of
perceptually unstable stimuli. This class includes retinally
stabilized images, faint stimuli subject to fading, and ambiguous
images in which figure-ground or depth reverse. Across these
stimuli a variety of perceptual mechanisms have been invoked to
explain alterations in the percept. These range from adaptation of
retinal receptors and binocular rivalry to dynamic alternations in
perceptual organization and attention. We will report a series of
experiments investigating modulatory effects of attention during an
adaptation period on subsequent perception of afterimages.
Observers directed their attention during adaptation to one of two
superimposed objects. Attention was directed volitionally, and, in
some conditions, was also 'captured' by oscillatory motion of the
attended or unattended object. The oscillation acted to segment the
display and possibly to attract attention. When one object
oscillated, observers tended to report that the other object was
more visible in the afterimage. A control experiment suggested that
the oscillation did not affect the duration of the afterimage. When
color distinguished the two objects, observers tended to report
that the unattended object was more visible in the afterimage. When
neither oscillation nor color distinguished the objects from each
other, observers tended to report both objects together in the
afterimage. These results suggest that attention during adaptation
weakens the afterimage of the attended object.
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