Testing a postselectional account of across-dimension switch costs.

In visual search for a pop-out target, responses are faster when the target dimension from the previous trial is repeated than when it changes. Currently, it is unclear whether these across-dimension switch costs originate from processes that guide attention to the target or from later processes (e.g., target identification or response selection). The present study tested two critical predictions of a response-selection account of across-dimension switch costs-namely, (1) that switch costs should occur even when visual attention is guided by a completely different feature and (2) that changing the target dimension should affect the speed of responding, but not the speed of eye movements to the target. The results supported both predictions, indicating that changes of the target dimension do not affect early processes that guide attention to the target but, rather, affect later processes, which commence after the target has been selected.