[Influence of attentional setting and priming on the inter-trial facilitation effect on pop-out]

In visual search situations, it is known that not only bottom-up factors relative to the presented stimulus display but also top-down factors, which include foreknowledge about the target or observers' strategies for the task, have an influence on search performance. The present study examines how top-down attentional control settings affect the visual search process by using the within-dimension facilitation (WDF) and the inter-trial facilitation (ITF) effects. In Experiment 1 we showed the WDF effect using foreknowledge about the target-defining dimension within one block. In Experiment 2 we found the ITF effect using foreknowledge about the target-defining dimension in every trial. These results suggest that search performance is improved both top-down attentional setting using foreknowledge and inter-trial priming by repetition of target-defining dimensions, and they are interactive. Furthermore, the influence of the priming effect strongly appeared when observers had an attentional setting every trial. These results show that the magnitude of bottom-up inter-trial priming effects depends on the top-down attentional setting.