Abstract
Visual events often do not reach awareness because of temporal limitations on visual attention. For example, observers frequently fail to identify the second of two targets (T1 and T2) embedded in a rapid serial visual presentation, when T2 appears 200–500 ms after T1 (attentional blink: AB). It has been generally accepted that the AB deficit reflects a failure to consolidate T2 into working memory. However, the temporal dynamics of consolidation of targets during the AB period remains unclear. To investigate this issue, we focused on a sparing effect in which T2 and also T3 (third target) identification is unimpaired when triple targets are presented successively (Lag-1 and Lag-2 sparing). We examined the pace at which successively presented targets are consolidated by combining the three target paradigm and measurement of P3 event-related potential which is known to reflect updating processes in working memory. We hypothesized that if the visual system consolidated multiple targets simultaneously, a single P3 component would be observed. On the other hand, if the system consolidated each target independently, separate P3 components would be observed for each target. Behavior scores indicated Lag-1 and Lag-2 sparing, as well as the AB deficit. The results revealed P3 components elicited separately by each target at the midline parietal site (Pz) when Lag-1 and Lag-2 sparing occurred. We found, for the first time, the discrete consolidation of sequentially presented targets. This finding suggests that the successively presented targets can be consolidated independently every 100 ms. The present results are inconsistent with conventional AB models assuming that the AB deficit occurs because the delay of T1 consolidation directly blocks T2 consolidation. Rather we suggest that an attentional event or suppression triggered by distractors between the targets impairs T2 consolidation.