Popout Attention with two foils: linear dependence and dimensional interaction


Automatic parallel processing occurs in visual search when a target differs from other display objects on a salient visual dimension and the phenomenon is termed ‘popout’. The present two studies answers the question: Do the interference effects cancel or add? Both studies used a ring of twelve fixed-size green circles with embedded Gabors oriented vertically or horizontally. Targets and foils were one of green square, a larger green circle, or a red circle. Each of these served as a target for one of the three sessions, with the others serving as foils. In one task the observer found the target and reported its Gabor orientation. The other task used targets only on one half the trials and the observer reported target presence or absence. In both tasks accuracy was uniformly high. In both tasks RT interference increased from one to two foils, the slowing mainly isolated to the slowest decile of RTs.

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