Top-down preparation contributes to intertrial priming in singleton search.

This study examined the influence of top-down preparation on singleton search performance. The method involved presentation of a single item that was unpredictably blue or orange, followed by a singleton search display that was unpredictably a blue target with orange distractors or vice versa. Preparation was instantiated by instructing participants to respond to the single item only if it was a particular colour (e.g., "respond only to blue single items"). The subsequent colour-singleton search target was either blue or orange. In a prior study with this method, participants prepared for the same single-item colour on all trials, and search performance was more than 200 ms faster when the prepared-for colour matched the colour singleton target than when it mismatched the colour singleton target (Sclodnick et al., Canadian Journal of Experimental Psychology/Revue Canadienne de Psychologie Expérimentale, 78, 129-135, 2024). In the present study, Experiments 1, 2a/2b, and 3a/3b demonstrate that a similar but smaller magnitude effect occurs when preparation for a particular single item colour is cued randomly from trial to trial. Experiments 2a/2b demonstrate that this preparatory effect is sensitive to the temporal interval between single-item and search tasks, but only when preparation is cued on a trial-to-trial basis. Experiments 3a/3b demonstrate that this preparatory effect is reduced with increases in display size, but still robust with display sizes up to nine items. Together, the results demonstrate that memory representations that result from both a single instance of top-down preparatory control and multiple similar instances of top-down preparatory control can carry over to influence subsequent singleton search performance.