THE LINEAR SEPARABILITY EFFECT IN COLOR VISUAL-SEARCH - RULING OUT THE ADDITIVE COLOR HYPOTHESIS

Bauer, Jolicoeur, and Cowan (1996b, 1996c) demonstrated difficult visu al search for color targets that were not linearly separable tin color space) from two distracter colors and easier search for Linearly sepa rable targets. This suggested that search is mediated by a chromatical ly linear discrimination mechanism (see D'Zmura, 1991). However, in th ose experiments, the targets that were not linearly separable fell mid way between the distracter colors and thus corresponded to the admix o f the distracter colors. An alternate interpretation of the results of Bauer et al. is that search was more difficult when the target corres ponded to the distracter admix than when it did not. We tested this hy pothesis in three experiments by contrasting conditions in which a tar get that was not linearly separable did or did not correspond to the a dmix of the distracter colors. In all cases, a target that was not Lin early separable produced difficult search, demonstrating that linear s eparability determines search performance.