hide
Free keywords:
-
Abstract:
Visual search is often conducted in 3-D space. However, little is known about search behaviour in 3-D space. Two different hypotheses have been put forward as to how stereoscopic depth cues can be used to enhance search efficiency: either by splitting the visual scene into depth planes, which are subsequently searched in turn (Nakayama and Silverman, 1986 Nature 320 264 - 265), or by grouping of similar visual information (even across 3-D space) into 'kernels', which are then searched in turn (Chau and Yeh, 1995 Perception Psychophysics 57 1032 - 1044). We contrasted these two hypotheses by studying two conjunctive searches with stereoscopic depth and colour. In experiment 1 this search was conducted across two depth planes and in experiment 2 across six depth planes. The six depth planes were subdivided into two triplets of depth planes, with the relative disparity 'within' a triplet being smaller than 'between' the two triplets, so that the two triplets appeared as two perceptually different kernels with similar chromatic and stereoscopic depth information. If the visual system splits up the visual scene into depth planes (as suggested by Nakayama and colleagues), search performance should be higher with six depth planes than with two. In contrast, if the visual system uses the chromatic and stereoscopic depth information to group similar visual information into kernels, visual-search performance should not differ appreciably between the two experiments (as suggested by Chau and Yeh, 1995 loco cit.), given that both displays consist of two perceptually different kernels. Our results indicate that search performance did not differ significantly between the experiments and search times were unaffected by the number of depth planes. Our data, thus, supports the hypothesis that the visual system groups similar visual information into kernels and then searches these kernels in turn.
