Categorical effects in visual search for colour

Abstract

The role of categorization in visual search was studied in 3 colour search experiments where the target was or was not linearly separable from the distractors. The linear separability effect refers to the difficulty of searching for a target that falls between the distractors in CIE colour space (Bauer, Jolicoeur, & Cowan, 1996b). Observers performed nonlinearly separable searches where the target fell between the two types of distractors in CIE colour space. When the target and distractors fell within the same category, search was difficult. When they fell within three distinct categories, response times and search slopes were significantly reduced. The results suggest that categorical information, when available, facilitates search, reducing the linear separability effect.

The data for Experiment 1 were collected as part of the second author's thesis. Experiment 1 was presented at the 25th European Conference on Visual Perception, Glasgow, August 2002.

The data for Experiment 1 were collected as part of the second author's thesis. Experiment 1 was presented at the 25th European Conference on Visual Perception, Glasgow, August 2002.

Acknowledgments

We are grateful to the observers who took part in the experiments, and to Pierre Jolicoeur and John Hodsoll for their very helpful comments. Michael Pilling is now at the MRC Institute of Hearing Research (Nottingham University Section).

Notes

The data for Experiment 1 were collected as part of the second author's thesis. Experiment 1 was presented at the 25th European Conference on Visual Perception, Glasgow, August 2002.

¹Although the CIELUV distances between adjacent colours were the same in the within- and cross-category sets, the two sets did not have the same luminance in Experiment 1, possibly confounding the results. Subsequent experiments controlled for this.