Priming of pop-out: II. The role of position.

In an earlier paper (Maljkovic & Nakayama, 1994) we showed that repetition of an attention-driving feature primes the deployment of attention to the same feature on subsequent trials. Here we show that repetition of the target position also primes subsequent trials. Position priming shows a characteristic spatial pattern. Facilitation occurs when the target position is repeated on subsequent trials, and inhibition occurs when the target falls on a position previously occupied by a distractor. Facilitation and inhibition also exist, though somewhat diminished, for positions adjacent to those of the target and distractors. Assessing the effect of a single trial over time, we show that the characteristic memory trace exerts its strongest influence on immediately following trials and decays gradually over the succeeding, approximately five to eight, trials. Throughout this period, target-position facilitation is always stronger than distractor-position inhibition. The characteristics of position priming are also seen under conditions in which the attention-driving feature either stays the same or differs from the previous trial, suggesting that feature and position priming operate independently. In a separate experiment, using the fact that position priming is cumulative over trials, we show that position priming is largely object- or landmark-centered.