Repetition effects in visual search.

Maljkovic and Nakayama (1994) demonstrated an automatic benefit of repeating the defining feature of the target in search guided by salience. Thus, repetition influences target selection in search guided by bottom-up factors. Four experiments demonstrate this repetition effect in search guided by top-down factors, and so the repetition effect is not merely part of the mechanism for determining what display elements are salient. The effect is replicated in singleton search and in three situations requiring different degrees of top-down guidance: when the feature defining the target is less salient than the feature defining the response, when there is more than one singleton in the defining dimension, and when the target is defined by a conjunction of features. Repetition does not change the priorities of targets, relative to distractors: Display size affects search equally whether the target is repeated or changed. More than one mechanism may underlie the repetition effect in different experiments, but assuming that there is a unitary mechanism, a short-term episodic memory mechanism is proposed.