Department of Psychology, University of Iowa.
J Exp Psychol Hum Percept Perform. 2013 Oct;39(5):1340-51. doi: 10.1037/a0031616. Epub 2013 Feb 11.
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 noncircular 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 spillover 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. We conclude that rather than be arbitrarily defined, perceptual load might be defined by well-characterized, continuous factors that influence visual search.
一种关于注意的早期与晚期选择争论的解释认为，知觉负载决定了选择的位置。在低负载条件下，注意力在后期处理水平上选择刺激，但在高负载条件下，注意力在早期水平上选择刺激。尽管知觉负载理论取得了成功，但知觉负载的非循环定义仍然难以捉摸。我们通过使用在视觉搜索中广泛研究的操纵来研究影响知觉负载的因素，即目标-分心物相似性和分心物-分心物相似性。与之前的工作一致，当目标和分心物不同且显示的分心物是同质的时，搜索效率最高；无论显示的异质性如何，当目标-分心物相似性增加时，搜索效率都会降低。重要的是，我们在一个典型的知觉负载任务中使用了相同的刺激，该任务测量了对任务无关的侧翼的注意溢出。我们发现搜索效率和知觉负载之间存在很强的对应关系；产生高效搜索的刺激会产生侧翼干扰效应，表明这种显示涉及低知觉负载。在产生效率较低搜索的显示中，侧翼干扰效应降低。此外，我们的结果表明，搜索难度（由搜索截距测量）对知觉负载的影响很小。我们得出的结论是，知觉负载可能不是任意定义的，而是可以通过影响视觉搜索的特征明确、连续的因素来定义。
