Academic journal article Perception and Psychophysics

Visual, Auditory, and Cross-Modality Dual-Task Costs: Electrophysiological Evidence for an Amodal Bottleneck on Working Memory Consolidation

Academic journal article Perception and Psychophysics

Visual, Auditory, and Cross-Modality Dual-Task Costs: Electrophysiological Evidence for an Amodal Bottleneck on Working Memory Consolidation

Article excerpt

When two masked, attended targets (T1 and T2) are presented within approximately half a second of each other, report of T2 is poor, compared with when the targets are presented farther apart in time-a phenomenon known as the attentional blink (AB; Raymond, Shapiro, & Arnell, 1992). Some researchers have suggested that an amodal bottleneck on working memory consolidation underlies the AB (see, e.g., Arnell & Jolicoeur, 1999). In the present work, T1 was masked, whereas T2 was unmasked. The modality of T1 (visual or auditory) and the modality of T2 (visual or auditory) were factorially manipulated across four experiments. For all modality combinations, T2's P3 event-related brain potential component was found to be delayed when T2 was presented soon after T1 (lag 3), compared with when T1 and T2 were presented farther apart (lag 8). Results suggest that the working memory consolidation bottleneck is amodal in nature, and provide evidence that visual, auditory, and cross-modality ABs all result from a bottleneck on consolidation operations.

When two masked targets both require attention, and are presented within half a second of each other, report of the second target (T2) is poor (Broadbent & Broadbent, 1987; Raymond, Shapiro, & Arnell, 1992). In contrast, T2 report is unimpaired when T2 is presented more than half a second after the first target (T1), or when T1 does not require attention (Raymond et al., 1992). This temporary reduction in the accuracy of T2 report has been called the attentional blink (AB; Raymond et al., 1992). Almost all theoretical models of the AB suggest that T2 performance suffers while limited capacity attentional resources are occupied with the processing of T1 (Shapiro, Arnell, & Raymond, 1997). Some of these models postulate a bottleneck on conscious stimulus identification and/or consolidation. For example, in their two-stage model, Chun and Potter (1995) propose that T2 is processed through the first stage, in which a high level visual representation is created and meaning information is extracted. When T1 and T2 are separated by a large amount of time, T2 processing can then proceed to stage 2, in which it is consciously identified and encoded in working memory for report. Stage 2 processing is expensive in terms of time and resources. This means that when T2 follows soon after T1, and T1 is still undergoing stage 2 processing, T2 must wait to gain access to stage 2. IfT2 is trailed by a mask, its temporary representation will be overwritten by the mask, stage 2 processing will fail, and subsequent report accuracy will be reduced, resulting in an AB. Jolicoeur (1998, 1999) and Jolicoeur and Dell'Acqua (1998, 1999) have similarly proposed a bottleneck on stimulus consolidation, whereby consolidation of T2 into working memory cannot proceed until consolidation of T1 has been completed. These authors further suggest that the processing resources needed for stimulus consolidation in working memory are the same as those required for responseselection operations.

Both behavioral and electrophysiological studies have provided clear evidence supporting these models' assumption of a postperceptual locus of the AB. For example, the AB is reduced if T2 is the participant's own name (Shapiro, Caldwell, & Sorensen, 1997) or a taboo word (Anderson, 2005). Also, a blinked T2 can semantically prime a subsequent target (Shapiro, Driver, Ward, & Sorensen, 1997). Luck, Vogel, and Shapiro (1996) showed that the N400 event-related brain potential (ERP), which is sensitive to semantic match/mismatch, is fully intact during the AB, indicating semantic activation of T2. There is also evidence to support the assumption that it is T2 stimulus consolidation that is impaired or delayed during the AB. For example, Vogel, Luck, and Shapiro (1998) and Vogel and Luck (2002) found that the difference wave for the P3 ERP component was dramatically attenuated during the AB. The P3 (or P300) size differs for rare and frequent task-defined events. …

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