Abstract
When two targets (T1, T2) are inserted in a stream of distractors, accuracy in identifying T2 is impaired if the interval between T1 and T2 is short. Di Lollo et al., (2005) proposed that this T2-deficit, known as the attentional blink (AB), results from a temporary loss of control over the current attentional set. Specifically, when the system is processing T1, it is vulnerable to an exogenously-triggered switch in attentional set caused by the items following T1. This exogenous filter reconfiguration leaves the system poorly prepared for T2 (if the items do not match) or well prepared (if the items match), thereby influencing the magnitude of the T2-deficit. The present study tested the limits of this system configuration process. Observers were presented with targets from a set of numbers and letters (1,2,3,A,B,C). Because targets were of both types, observers could not prepare optimally to select items based on class membership; each had to be coded separately. We varied whether the targets matched in class (numbers vs. letters) and whether the items intervening the targets were numbers or letters. An AB deficit was observed in all conditions, with no effect of the similarity between intervening items and T2. This finding establishes a clear limit on the nature of the task for which an input filter can be set optimally, and on when the system is vulnerable to exogenous reconfiguration. Additional experiments examined the conditions under which optimal task filters can be prepared in the perception of targets in rapid visual streams.