| Visual search performance is influenced by many factors including number of targets, display set size, the similarity of the targets to the distractors, and perceptual grouping characteristics (Grossberg, Mingolla, & Ross, 1994). Three visual search models were investigated that make differing predictions about the effect of perceptual grouping on performance, Feature Integration Theory (Treisman & Sato, 1990), Guided Search 2.0 (Wolfe, 1994), and Spatial and Object Search (Grossberg, et al., 1994). Both a response time (RT) task and a stimulus onset asynchrony (SOA) task were used. The perceptual grouping characteristics tested were (a) proportion of target color versus target pattern distractors, (b) group size of the response color, (c) group size of the response pattern, (d) number of color groups, (e) number of pattern groups, and (f) the color of the area surrounding the stimuli.; The results indicate that several perceptual grouping features play a role in the RT and SOA tasks. Feature Integration Theory (Treisman & Sato, 1990) was rejected because it did not predict any of these perceptual grouping effects. The data indicated that visual search performance with difficult pattern discrimination was facilitated by a larger perceptual group of the target color. Guided Search Theory (Wolfe, 1994) incorrectly predicted that visual search performance would be better with fewer distractors of the target color, especially if pattern discrimination was difficult. Only the Spatial Object Search model was consistent with these data (Grossberg, Mingolla, & Ross, 1994). Spatial and Object Search correctly predicted that performance would be better when there were more target color stimuli present, and when the target was within larger groups of target color. Furthermore, Spatial and Object Search correctly predicted that a larger number of perceptual groups would impair performance. |
