Trial history contributes to the optimal tuning of attention.

In visual search tasks, targets are difficult to find when they are similar to the surrounding nontargets. In this scenario, it is optimal to tune attention to target features that maximize the difference between target and nontargets. We investigated whether the optimal tuning of attention is driven by biases arising from previously attended stimuli (i.e., trial history). Consistent with the effects of trial history, we found that optimal tuning was stronger when a single target-nontarget relation was repeated than when two target-nontarget relations alternated randomly. Detailed analysis of blocks with random alternation showed that optimal tuning was stronger when the target-nontarget relation probed in the current trial matched the relation in the previous trial. We evaluated several mechanisms that may underlie the effects of trial history, such as priming of attentional set, switch costs, and sensory adaptation. However, none of the accounts was able to fully account for the pattern of results. (PsycInfo Database Record (c) 2024 APA, all rights reserved).