How Quickly Can Attention Affect Form Perception

Abstract : It is possible to attend to different locations in the visual field without changing fixation. Recently, some researchers have suggested that sequenced of such internal attention shifts may be a necessary part of perception. This seems to require that attention be shifted very rapidly, since a complex scene can often be seen with only brief presentation. The present experiments trace the time course of the effects of internal attention shifts on form discrimination accuracy. Observers were cued to attend to one of four peripheral locations while maintaining central fixation. After a brief variable interval, four T-like target figures were presented, one at each location, followed by masks. The observer then identified the target that appeared at the cued location. The first two experiments showed that rapid-onset attention effects, which occur when cue is presented near the target, can also be obtained with a cue presented fixation, given sufficient practice. This argues that such effects are indeed attentional in nature and are not due to local cur-target presentation is considered, the latency of attention effects is very short. Furthermore, attention increases the rate at which information is extracted from a stimulus. Keywords: Attention shift, Form discrimination, Form perceptive, Visual perception.