Abstract
When searching for two targets in a stream of rapidly presented items, detection of the second target (T2) suffers if presented within 400–600ms of the first (T1). Prevalent models of this “attentional blink” (Raymond et al, 1992) explain the deficit in terms of both attentional and memory-based capacity limitations (e.g. Chun & Potter, 1997; Shapiro et al, 1997). Recent evidence suggests that the AB occurs independently of manipulations of short term memory (STM) load, casting doubt on the role of memory operations in the AB (Akyurek & Hommel, 2005). Using a variant of the AB paradigm, we directly explored mechanisms of target retrieval from STM. Participants observed an eight item rapid serial visual presentation (RSVP) stream of letters and then judged whether two subsequently presented letters were present or absent in the stream. Importantly, participants were not instructed to search for pre-specified targets. This implies that attentional resources are allocated evenly throughout the stream (and not preferentially directed to T1) and that participants must rely on retrieving the targets from the STM store. Probed letters could occur at varying temporal proximities from each other (analogous to lag differences between T1 and T2 in typical AB tasks). Preliminary results indicate a typical attentional blink pattern: Poor T2 recall when presented in close temporal proximity to T1. Further, this ‘un-attentional (mnemonic) blink’ only occurred when target letters were probed in the same serial order as presented in the stream (and not when probed in reverse order). These findings suggest that retrieval of an item in STM may have inhibitory effects for other items stored in close temporal proximity and challenge key assumptions made in accounts of the AB.