Abstract
In a color-oddball search task, when a target's color in the current search display has been passively viewed in a preceding target-absent display (TAD), the response time (RT) to the target is slower than when the distractor's color in the current search display was passively viewed. The RT difference between the target-color preview and the distractor-color preview is known as distractor previewing effect (DPE). Four experiments were conducted to investigate the effects of target appearance predictability on the DPE by distributing trials in a blocked and a random fashion, in which the number of TAD presentations was fixed and varied within each block, respectively. Simultaneously, we examined history effects of multiple previews of target and distractor features (ranging from 0 to 2 in Exps. 1A and 2A; from 0 to 5 in Exps. 1B and 2B) on target response in the blocked (Exps. 1A and 1B) and random (Exps. 2A and 2B) designs. For the consecutive 2 TAD presentations a single (target or distractor) color was repeated twice, or target and distractor colors were alternated prior to the search display in Exps. 1A and 2A. In Exps. 1B and 2B, either a target or a distractor (not both) color was repeated in consecutively presented TADs. We found: (a) the size of the DPE increased as the number of TADs increased, with that increase more consistent in the random than in the blocked design; (b) the DPE occurred in both the 2 and 1 TAD conditions in the blocked design, but only in the 2 TAD condition in the random design; (c) the color previewed in the immediately preceding TAD (i.e.,one-back) influenced the RT more than the color in the two-back. These results demonstrate cumulative history effects with more emphasis on recent events and top-down response strategy on target selection.