Is pop-out search impaired during the period of the attentional blink?

The involvement of attention in pop-out visual search is controversial. According to some theories, efficient pop-out search is accomplished preattentively, while others claim the involvement of attention is essential. In the present work, the role of attention in performing pop-out search tasks was elucidated by manipulating the availability of attention using an attentional blink (AB) paradigm. In Chapter 2, the efficiency of pop-out search – indexed by the slope of response time (RT) functions over the number of items in the search array – was examined throughout the period of the AB. Search efficiency was found to be unaffected by the AB, although the overall level of RT was slower during the AB. These findings suggest the action of at least two separable mechanisms underlying performance in pop-out search tasks, indexed by level and efficiency of search, which are affected in different ways by the availability of attention. In Chapter 3, the role of selective attention in pop-out search was examined by measuring the onset latency of the N2pc, an event-related potential index of attentional selection. Both the RT and the N2pc measures were delayed during the AB, but the delay in N2pc was substantially shorter than that in RT. This pattern of results points to multiple sources of delay in the chain of processing events, as distinct from the single source postulated in current theories of the AB, and strongly suggests that selective attention is involved in pop-out search tasks. In Chapter 4, the relative exogenous and endogenous salience of two targets (T2, T3) presented throughout the period of the AB were manipulated in order to assess whether the perception of salience is impaired during the AB. The perception of temporal order of these targets was measured. Both exogenous and endogenous salience were found to be effective in modulating the perception of temporal order throughout the period of the AB, suggesting that the effect of salience is broadly additive with the overall AB effect. In Chapter 5, the implications of these findings for both search and the AB, are discussed and future research directions are proposed.