EXPRESS: The role of perceptual and cognitive load on inattentional blindness: a systematic review and three meta-analyses

The inattentional blindness phenomenon refers to situations where a visible but unexpected stimulus remains consciously unnoticed by observers. This phenomenon is classically explained as the consequence of insufficient attention, because attentional resources are already engaged elsewhere or vary between individuals. However, this attentional-resources view is broad and often imprecise regarding the variety of attentional models, the different pools of resources that can be involved in attentional tasks and the heterogeneity of the experimental paradigms. Our aim was to investigate whether a classic theoretical model of attention, namely the Load Theory, could account for a large range of empirical findings in this field by distinguishing the role of perceptual and cognitive resources in attentional selection and attentional capture by irrelevant stimuli. Since this model has been mostly built on implicit measures of distractor interference, it is unclear whether its predictions also hold when explicit and subjective awareness of an unexpected stimulus is concerned. Therefore, we conducted a systematic review and meta-analyses of inattentional blindness studies investigating the role of perceptual and/or cognitive resources. The results reveal that, in line with the perceptual account of the Load Theory, inattentional blindness significantly increases with the perceptual load of the task. However, the cognitive account of this theory is not clearly supported by the empirical findings analyzed here. Furthermore, the interaction between perceptual and cognitive load on inattentional blindness remains understudied. Theoretical implications for the Load Theory are discussed, notably regarding the difference between attentional capture and subjective awareness paradigms, and further research directions are provided.

Spatial suppression due to statistical regularities in a visual detection task

Increasing evidence demonstrates that observers can learn the likely location of salient singleton distractors during visual search. To date, the reduced attentional capture at high-probability distractor locations has typically been examined using so called compound search, in which by design a target is always present. Here, we explored whether statistical distractor learning can also be observed in a visual detection task, in which participants respond target present if the singleton target is present and respond target absent when the singleton target is absent. If so, this allows us to examine suppression of the location that is likely to contain a distractor both in the presence, but critically also in the absence, of a priority signal generated by the target singleton. In an online variant of the additional singleton paradigm, observers had to indicate whether a unique shape was present or absent, while ignoring a colored singleton, which appeared with a higher probability in one specific location. We show that attentional capture was reduced, but not absent, at high-probability distractor locations, irrespective of whether the display contained a target or not. By contrast, target processing at the high-probability distractor location was selectively impaired on distractor-present displays. Moreover, all suppressive effects were characterized by a gradient such that suppression scaled with the distance to the high-probability distractor location. We conclude that statistical distractor learning can be examined in visual detection tasks, and discuss the implications for attentional suppression due to statistical learning.

Attentional Capture From Inside vs. Outside the Attentional Focus

In this study, we jointly reported in an empirical and a theoretical way, for the first time, two main theories: Lavie’s perceptual load theory and Gaspelin et al.’s attentional dwelling hypothesis. These theories explain in different ways the modulation of the perceptual load/task difficulty over attentional capture by irrelevant distractors and lead to the observation of the opposite results with similar manipulations. We hypothesized that these opposite results may critically depend on the distractor type used by the two experimental procedures (i.e., distractors inside vs. outside the attentional focus, which could be, respectively, considered as potentially relevant vs. completely irrelevant to the main task). Across a series of experiments, we compared both theories within the same paradigm by manipulating both the perceptual load/task difficulty and the distractor type. The results were strongly consistent, suggesting that the influence of task demands on attentional capture varies as a function of the distractor type: while the interference from (relevant) distractors presented inside the attentional focus was consistently higher for high vs. low load conditions, there was no modulation by (irrelevant) distractors presented outside the attentional focus. Moreover, we critically analyzed the theoretical conceptualization of interference using both theories, disentangling important outcomes for the dwelling hypothesis. Our results provide specific insights into new aspects of attentional capture, which can critically redefine these two predominant theories.

A bridge to progress further afield: The promise of a common framework on attentional capture

Although physical salience looms large in the attentional capture literature, stimuli can also capture attention via salience deriving from non-physical factors. Such psychological salience can stem, for example, from the emotional resonance of stimuli or their relevance to a person’s expertise. We consider how insights from a recently proposed framework for attentional capture can be used to advance theory and drive research on the role of emotion-driven attentional biases in clinical disorders and on how attentional allocation changes with the development of perceptual expertise. In return, we wonder how their common framework can be enriched through considerations of psychological salience.