Visual short-term memory load strengthens selective attention
Perceptual load theory accounts for many attentional phenomena; however, its mechanism remains elusive because it invokes underspecified attentional resources. Recent dual-task evidence has revealed that a concurrent visual short-term memory (VSTM) load slows visual search and reduces contrast sensitivity, but it is unknown whether a VSTM load also constricts attention in a canonical perceptual load task. If attentional selection draws upon VSTM resources, then distraction effects—which measure attentional “spill-over”—will be reduced as competition for resources increases. Observers performed a low perceptual load flanker task during the delay period of a VSTM change detection task. We observed a reduction of the flanker effect in the perceptual load task as a function of increasing concurrent VSTM load. These findings were not due to perceptual-level interactions between the physical displays of the two tasks. Our findings suggest that perceptual representations of distractor stimuli compete with the maintenance of visual representations held in memory. We conclude that access to VSTM determines the degree of attentional selectivity; when VSTM is not completely taxed, it is more likely for task-irrelevant items to be consolidated and, consequently, affect responses. The “resources” hypothesized by load theory are at least partly mnemonic in nature, due to the strong correspondence they share with VSTM capacity.
KeywordsPerceptual load Selective attention Visual short-term memory
This research was supported in part by grants from the Nissan Motor Company, the Toyota Motor Company, the National Institutes of Health (R01AG026027), the National Science Foundation (BCS 11–51209), and the University of Iowa Graduate College summer fellowship awarded to the lead author. Thanks to Joshua Cosman and Daniel Vatterott for many helpful discussions. Correspondence should be addressed to Shaun P. Vecera, Department of Psychology, E11 Seashore Hall, University of Iowa, Iowa City, IA 52242–1407. Electronic mail can be sent to firstname.lastname@example.org.
- Konstantinou, N., & Lavie, N. (in press). Dissociable roles of different types of working memory load in visual detection. Journal of Experimental Psychology: Human Perception and Performance. Advance online publication. doi: 10.1037/a0033037
- Roper, Z. J. J., Cosman, J. D., Vecera, S. P. (in press). Perceptual load is determined by factors known to influence visual search. Journal of Experimental Psychology: Human Perception, and Performance, Advance online publication. doi: 10.1037/a0031616
- Scalf, P. E., Torralbo, A., Tapia, E., & Beck, D. M. (2013). Competition explains limited attention and perceptual resources: implications for perceptual load and dilution theories. Frontiers in Psychology, 4. doi: 10.3389/fpsyg.2013.00243