A. B. Leber & H. E. Egeth
Johns Hopkins University

Recent research suggests that attentional control is largely influenced by top-down processes. It follows that it should behave like other executive control functions, and we explored this intuition by creating tasks – using single-target rapid serial visual presentation (RSVP) - requiring subjects to switch their attentional sets from trial to trial (similar to traditional task switching paradigms). While our early work (Leber & Egeth, 2001) found a pattern of data typical of traditional switching tasks, the characteristic residual switch cost (Rogers & Monsell, 1995) was not observed. Present work manipulated the temporal position of the target in the RSVP stream, and residual costs were observed for earlier targets. The existence of the cost supports the notion that attentional control is like other executive functions, and its dependence on temporal position shows that engagement in the task (rather than completion) is necessary to overcome the residual cost.