Perceptual load and the capture of spatial attention by color singletons

Recent experiments have cast considerable doubt upon the ability of color singletons to capture spatial attention in a stimulus-driven manner. Despite the lack of evidence for it in the laboratory, there are many anecdotal reports of stimulus-driven capture in real-world settings. Perhaps a critical difference between laboratory and real-world visual scenes is the amount of relevant information, or perceptual load. Scenes with low perceptual load (as when one is focused on a single visual object) might free attentional resources, allowing them to be more easily captured by color singletons. To test this hypothesis, we manipulated perceptual load in a visual search task with irrelevant flanking letters that were sometimes color singletons. If reduced perceptual load increases susceptibility to capture by color singletons, then the presence of a color singleton should slow responses and increase flanker-target compatibility effects. Contrary to this prediction, we found no evidence of capture under high or low perceptual load

“Top-down” Does Not Mean “Voluntary”

Attention researchers have long debated the roles of top-down and bottom-up mechanisms in controlling attention. Theeuwes (2018) has argued that that top-down control is much less common than typically assumed and that a third mechanism—selection history—plays an underappreciated role in guiding visual attention. Although Theeuwes has made a strong case for the importance of selection history, his arguments for a limited role of top-down mechanisms involve conflating the terms “top-down” and “voluntary.” Cognitive psychologists typically use the term “top-down” processing to refer to any perceptual phenomenon that is influenced by context, learning, or expectation, which would include selection history. This highlights a broad problem in attention capture research: The terms used to describe attentional control are often poorly defined, and much current debate seems to be related to the meaning of words. To move forward in understanding the actual mechanisms of attentional control, we must agree on what terms such as “top-down” and “bottom-up” actually mean

Breaking through the attentional window: Capture by abrupt onsets versus color singletons

Theeuwes (2004) proposed that stimulus-driven capture occurs primarily for salient stimuli that fall within the observer's attentional window, such as when performing a parallel search. This proposal, supported by some studies, can explain many seemingly discrepant results in the literature. The present study tested this proposal using a modified pre-cuing paradigm. Search mode was manipulated via target-distractor similarity in color space. In the parallel search condition, the orange target “popped out” from a set of distantly colored distractors (blue and green). In the serial search condition, the orange target was more difficult to find amongst a set of similarly colored distractors (yellow and red). In Experiments 1 and 2, cue validity effects for irrelevant color singleton cues were greater under parallel search than serial search, at least partially replicating previous studies favoring the attentional window account (e.g., Belopolsky et al., 2007). We found the opposite pattern, however, for capture by abrupt onsets (Experiments 3 and 4). Here, capture effects were actually greater under serial search. In sum, parallel search appears to facilitate capture by color singletons, yet inhibit capture by abrupt onsets.Keywords: attentional capture, visual search, spatial attentio