Priming of pop-out: I. Role of features

We examined a visual search task, in which observers responded to the high-acuity aspect of a popout target (shape of an odd-colored diamond or vernier offset of an odd spatial-frequency patch). Repetition of the attention-driving feature (color or spatial frequency) in this task primes the popout; repetition of the high-acuity aspect (shape, vernier offset) does not. Priming of pop-out is due to a decaying memory trace of the attention-focusing feature laid down with each trial. The trace exerts a diminishing effect over the following five to eight trials (≈30 sec), and its influence over this time is cumulative. Observers cannot willfully overcome the priming, which suggests that it is passive and autonomous. Both target facilitation and distractor inhibition are evident; the former has a greater effect. The phenomenon shows complete binocular transfer.