Department of Psychology, University of Iceland, Iceland.
Department of Cognitive Science, University of Malta, Malta.
Cognition. 2020 Jan;194:104032. doi: 10.1016/j.cognition.2019.104032. Epub 2019 Aug 30.
Visual search tasks play a key role in theories of visual attention. But single-target search tasks may provide only a snapshot of attentional orienting. Foraging tasks with multiple targets of different types arguably provide a closer analogy to everyday attentional processing. Set-size effects have in the literature formed the basis for inferring how attention operates during visual search. We therefore measured the effects of absolute set-size (constant target-distractor ratio) and relative set-size (constant set-size but target-distractor ratio varies) on foraging patterns during "feature" foraging (targets differed from distractors on a single feature) and "conjunction" foraging (targets differed from distractors on a combination of two features). Patterns of runs of same target-type selection were similar regardless of whether absolute or relative set-size varied: long sequential runs during conjunction foraging but rapid switching between target types during feature foraging. But although foraging strategies differed between feature and conjunction foraging, surprisingly, intertarget times throughout foraging trials did not differ much between the conditions. Typical response time by set-size patterns for single-target visual search tasks were only observed for the last target during foraging. Furthermore, the foraging patterns within trials involved several distinct phases, that may serve as markers of particular attentional operations. Foraging tasks provide a remarkably intricate picture of attentional selection, far more detailed than traditional single-target visual search tasks, and well-known theories of visual attention have difficulty accounting for key aspects of the observed foraging patterns. Finally, we discuss how theoretical conceptions of attention could be modified to account for these effects.
视觉搜索任务在视觉注意理论中起着关键作用。但是，单一目标搜索任务可能仅提供注意力定向的快照。具有不同类型多个目标的觅食任务可以说更接近日常注意力处理的类比。在文献中，集合大小效应为推断注意力在视觉搜索过程中的运作方式提供了基础。因此，我们测量了绝对集合大小（恒定的目标-干扰物比率）和相对集合大小（恒定的集合大小，但目标-干扰物比率变化）对“特征”觅食（目标与干扰物在单个特征上不同）和“结合”觅食（目标与干扰物在两个特征的组合上不同）过程中觅食模式的影响。无论绝对集合大小还是相对集合大小发生变化，相同目标类型选择的连续运行模式都相似：在结合觅食期间进行长序列运行，但在特征觅食期间快速切换目标类型。但是，尽管特征觅食和结合觅食的觅食策略不同，但令人惊讶的是，在觅食试验中，目标之间的时间间隔在两种条件之间差异不大。在单一目标视觉搜索任务中，典型的按集合大小模式的反应时间仅在觅食过程中最后一个目标时观察到。此外，试验内的觅食模式涉及几个不同的阶段，这些阶段可能是特定注意力操作的标志。觅食任务提供了注意力选择的非常复杂的画面，远比传统的单一目标视觉搜索任务详细，并且众所周知的视觉注意理论难以解释观察到的觅食模式的关键方面。最后，我们讨论了如何修改注意力的理论概念来解释这些影响。
