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Zachary Roper, Shaun Vecera; Distractor processing in low perceptual load is determined by the availability of visual short-term memory resources. Journal of Vision 2012;12(9):289. doi: 10.1167/12.9.289.
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Recent additions to the early versus late attentional selection debate have led to the conceptualization of perceptual load theory which states that task-irrelevant stimuli can only be ignored when resources are sufficiently taxed to engage selective attention. However, the nature of the resources that are putatively depleted under high perceptual load is ill-defined. Because many experiments designed to examine perceptual load have employed brief exposure durations, it is tenable that visual short-term memory (VSTM) may play a role in visual selection under high perceptual load conditions. Overly-limited exposure durations would force observers to perform the task on an internal representation of the stimuli due to fleeting bottom-up support from the display. A consequence of the demand placed upon internal maintenance of task-relevant information coupled with greater entropy in high perceptual load displays may manifest itself as elevated demands on VSTM consolidation compared to the demands engendered by relatively austere low perceptual load displays. With that, we predicted that a concurrent VSTM load would reduce observers’ capacity to internally represent task-relevant stimuli thereby allowing low perceptual load displays to reveal the resource limitations of high load displays. However, if VSTM taxes cognitive processes involved in distractor suppression (Lavie et al., 2004, JEP:General), then a VSTM load would increase distractor interference in low load displays. We found a significant flanker effect when subjects had to store one item in VSTM. The effect dissipated as VSTM load grew to two, three, and four items. A second experiment ruled out low-level perceptual influences of the VSTM displays. These results reveal that a concurrent VSTM load acts to reduce available resources which would otherwise be free to process task-irrelevant stimuli in low perceptual load. We propose that the resources taxed by high ‘perceptual’ load are in fact mnemonic rather than perceptual in nature.
Meeting abstract presented at VSS 2012
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