Perceptual organization and attention

It is widely assumed that the grouping of the visual field first described by the Gestalt psychologists and the related phenomenon of texture segregation occur very early in the processing of visual information and involve preattentive processes. All the recent evidence supporting this assumption comes from visual search experiments in which the subject is actively looking for a target and attending to the stimulus. The question at issue is whether these kinds of patterns are perceived under conditions of inattention, i.e., when observers are not searching for them. We performed six experiments to determine whether texture segregation and grouping by similarity or proximity are perceived under conditions of inattention. On the first two trials subjects were asked to report the longer arm of a briefly presented cross which was surrounded by a pattern of ungrouped small elements. On the third trial and subsequent control trials these elements were configured into grouping patterns and subjects queried about them immediately following their line length reports. The results establish that neither texture segregation nor grouping by similarity of lightness or proximity are perceived under conditions of inattention. They support the conclusion that there is an earlier stage of processing than that referred to as preattentive.