Abstract
Attention can be distributed in time as well as in space. Brain imaging studies suggest that orienting of attention in time and in space involves some common and some domain specific mechanisms (see Nobre, 2001). However, the similarities and differences between allocation of attention in time and in space have not yet been fully explored. Recently, Yashar and Lamy (2010) compared spatial visual search to search in an RSVP stream. They showed that during singleton search, target-feature activation and distractor-feature inhibition mechanisms are common to both temporal and spatial search. Post-hoc analyses of the RSVP task data revealed an additional effect: RTs were faster when on two consecutive trials the target happened to appear at the same rather than at a different temporal position. This temporal position priming (TPP) effect parallels the position priming effect found in spatial visual search (Maljkovic & Nakayama, 1996), in which repetition of target position in space speeds singleton search. This finding suggests that, as with spatial positions, temporal positions can be represented and encoded in implicit short-term memory, and that this encoded representation can guide the allocation of attention in time. In the present study we establish the existence of TPP and examine the similarities and differences between priming of position in space and priming of position in time. We show that TPP is eliminated when the target position in time is predictable. We also show that TPP is observed whether or not the target feature that is relevant for selection is constant or changes unpredictably. We conclude that (1) encoding of temporal position is automatic, (2) traces of the temporal position of the target on the previous trial facilitates search when the target position in time is uncertain, and (3) temporal position priming speeds processes related to engaging attention in target.