Visual attention and perceptual grouping

Abstract

Perceptual organization is thought to involve an analysis of both textural discontinuities and perceptual grouping. In earlier work, we found that textural discontinuities were detected normally even when visual attention was engaged elsewhere. Here we report how perceptual grouping is affected when visual attention is engaged by a concurrent visual task. To elicit perceptual grouping, we used the Gestalt demonstrations of grouping on the basis of proximity and of similarity. Four tasks were investigated, some requiring the observer to discriminate between horizontal and vertical grouping, and some requiring the observer to merely detect the presence or absence of grouping. Visual attention was engaged at the center of the display by a form identification task. The detection of a textural discontinuity served as a control task. Concurrent form identification conflicted with all four grouping tasks, resulting in a significant reduction of grouping performance in each case. No performance reduction was observed when either form identification or grouping discrimination was combined with the detection of a textural discontinuity. These results suggest that perceptual grouping and form identification compete for visual attention, whereas the detection of a textural discontinuity does not.

Grouping with and without attention

“…The poorer performance under the divided-attention conditionreplicated Barchilon Ben-Av et al (1992). What is noteworthy is that poorer performance was obtained even in the large-disparity condition, in which, under full attention, performance was virtually at ceiling level, suggesting that the arrowheads were grouped rather easily.…”

“…In an earlier series of experiments in which a dividedattention paradigm was used, Barchilon Ben-Av et al (1992) showed that the grouping operation appeared to demand attentional resources. They compared performance in a dual-task condition, in which the identification of the background pattern constituted the secondary task, with a condition in which it was the main task.…”

“…The question addressed in this report is whether grouping occurs preattentively (e.g., Treisman, 1986) or postattentively (e.g., Barchilon Ben-Av, Sagi, & Braun, 1992;Mack, Tang, Tuma, Kahn, & Rock, 1992). In one commonly used method (e.g., Barchilon Ben-Av et al, 1992), the effects that obtained under divided attention, where the grouping operation was the secondary task, are compared with those that obtained when it was the main or the sole task (full attention).…”

“…In one commonly used method (e.g., Barchilon Ben-Av et al, 1992), the effects that obtained under divided attention, where the grouping operation was the secondary task, are compared with those that obtained when it was the main or the sole task (full attention). If the grouped patterns were harder to discern under the divided-attention condition, the interpretation is that the grouping operation demanded attentional resources and, thus, could not have occurred preattentively.…”

Traditional and New Principles of Perceptual Grouping

“…Presumably, this is because they were not attending to the grouping array while their attention was focused on the task-relevant cross. This was taken as evidence that even if a pattern is at the centre of vision, grouping processes may not operate unless attention is specifically allocated to the pattern (also see Ben-Av, Sagi, & Braun, 1992). However, since then, others, using different paradigms, have uncovered evidence, often indirect, that at least some perceptual grouping may be operating pre-attentively (Kimchi, 2009;Lamy, Segal, & Ruderman, 2006;Moore & Egeth, 1997;Russell & Driver, 2005), although this is not the case for all types of grouping (Kimchi & Razpurker-Apfeld, 2004).…”