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Perceptual load corresponds with factors known to influence visual search
Journal article   Open access   Peer reviewed

Perceptual load corresponds with factors known to influence visual search

Zachary J. J Roper, Joshua D Cosman and Shaun P Vecera
Journal of experimental psychology. Human perception and performance, Vol.39(5), pp.1340-1351
10/2013
DOI: 10.1037/a0031616
PMCID: PMC3928141
PMID: 23398258
url
https://www.ncbi.nlm.nih.gov/pmc/articles/3928141View
Open Access

Abstract

One account of the early versus late selection debate in attention proposes that perceptual load determines the locus of selection. Attention selects stimuli at a late processing level under low-load conditions but selects stimuli at an early level under high-load conditions. Despite the successes of perceptual load theory, a non-circular definition of perceptual load remains elusive. We investigated the factors that influence perceptual load by using manipulations that have been studied extensively in visual search, namely target-distractor similarity and distractor-distractor similarity. Consistent with previous work, search was most efficient when targets and distractors were dissimilar and the displays contained homogeneous distractors; search became less efficient when target-distractor similarity increased irrespective of display heterogeneity. Importantly, we used these same stimuli in a typical perceptual load task that measured attentional spill-over to a task-irrelevant flanker. We found a strong correspondence between search efficiency and perceptual load; stimuli that generated efficient searches produced flanker interference effects, suggesting that such displays involved low perceptual load. Flanker interference effects were reduced in displays that produced less efficient searches. Furthermore, our results demonstrate that search difficulty, as measured by search intercept, has little bearing on perceptual load. These results suggest that perceptual load might be defined in part by well-characterized, continuous factors that influence visual search.
search difficulty perceptual load search efficiency visual search selective attention

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