Degraded stimulus visibility and the effects of perceptual load on distractor interference

The mechanisms of far transfer from cognitive training: specifying the role of distraction suppression

Cognitive training aims to produce a durable transfer to untrained abilities (i.e., far transfer). However, designing effective programs is difficult, because far transfer mechanisms are not well understood. Greenwood and Parasuraman (Neuropsychol 30(6):742-755. https://doi.org/10.1037/neu0000235 , 2016) proposed that the ability to ignore distractions is key in promoting far transfer. While the authors identified working-memory training based on the N-back task as an effective way to train distraction suppression, a recent meta-analysis concluded that this form of training rarely produces far transfer. Such inconsistency casts doubt onto the importance of distraction suppression in far transfer and calls for further examination of the role of this ability in cognitive training effectiveness. We propose here to conceptualize distraction suppression in the light of the load theory of attention, which distinguishes two mechanisms of distractor rejection depending on the level and type of information load involved: perceptual selection and cognitive control. From that standpoint, N-back training engages a single suppression mechanism, namely cognitive control, because it mainly involves low perceptual load. In the present study, we compared the efficacy of N-back training in producing far transfer to that of a new response-competition training paradigm that solicits both distraction suppression mechanisms. Response-competition training was the only one to produce far transfer effects relative to an active control training. These findings provided further support to Greenwood and Parasuraman's hypothesis and suggest that both selection perception and cognitive control need to be engaged during training to increase the ability to suppress distraction, hence to promote far transfer.

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.

Forgetting under difficult conditions: Item-method directed forgetting under perceptual processing constraints

Intentional forgetting of unwanted items is effortful, yet directed forgetting seems to improve when a secondary task is performed. According to the cognitive load hypothesis of directed forgetting, allocating attentional resources to another task improves forgetting by restricting unwanted encoding of to-be-forgotten (TBF) items. Alternatively, it might be that anything that makes studying more difficult will encourage greater effort to perform the task well and therefore lead to improved intentional forgetting. To assess these proposals we imposed data-processing limitations on study words in an item-method directed forgetting paradigm. Across six experiments, the perceptual quality of study words was manipulated by varying: (1) the duration of study word presentation (Experiments 1-4); (2) the contrast of the displayed word against its visual background (Experiment 5); or (3) the amount of visual background noise on which the word was presented (Experiment 6). In Experiments 4-6, a lexical decision task corroborated the difficulty of study word processing. Despite evidence that relatively low visual contrast and relatively high visual background noise, in particular, create challenging conditions, we found no evidence that perceptual quality impacts the magnitude of the directed forgetting effect. This work suggests that data limitations have no discernible effect on forgetting and corroborate that only attentional resource limitations improve directed forgetting.

Contrasting the Effects of Task Difficulty and Perceptual Load on Auditory Detection Sensitivity in Individuals with Autism

To test a central assumption of the increased perceptual capacity account in individuals with Autism Spectrum Disorder (ASD), the effects of perceptual load and target-stimulus degradation on auditory detection sensitivity were contrasted. Fourteen adolescents with ASD and 16 neurotypical controls performed a visual letter search task under three conditions: low perceptual load, high perceptual load and low perceptual load with a degraded target while simultaneously detecting an auditory tone in noise. For both participants with ASD and neurotypical controls, increasing perceptual load and target degradation increased task difficulty as indexed by reaction times and accuracy. However, only increasing perceptual load reduced subsequent auditory detection sensitivity. The study confirms that perceptual load, and not task difficulty, modulates selective attention in ASD.

Large inter-individual and intra-individual variability in the effect of perceptual load

This study examined whether the recurrent difficulty to replicate results obtained with paradigms measuring distractor processing as a function of perceptual load is due to individual differences. We first reanalyzed, at the individual level, the data of eight previously reported experiments. These reanalyses revealed substantial inter-individual differences, with particularly low percentage of participants whose performance matched the load theory's predictions (i.e., larger distractor interference with low than high levels of load). Moreover, frequently the results were opposite to the theory's predictions-larger interference in the high than low load condition; and often a reversed compatibility effect emerged-better performance in the incompatible than neutral condition. Subsequently, seven observers participated in five identical experimental sessions. If the observed inter-individual differences are due to some stable trait or perceptual capacity, similar results should have emerged in all sessions of a given participant. However, all seven participants showed large between-sessions variations with similar patterns to those found between participants. These findings question the theoretical foundation implemented with these paradigms, as none of the theories suggested thus far can account for such inter- and intra-individual differences. Thus, these paradigms should be used with caution until further research will provide better understanding of what they actually measure.

Concentration: The Neural Underpinnings of How Cognitive Load Shields Against Distraction

Whether cognitive load—and other aspects of task difficulty—increases or decreases distractibility is subject of much debate in contemporary psychology. One camp argues that cognitive load usurps executive resources, which otherwise could be used for attentional control, and therefore cognitive load increases distraction. The other camp argues that cognitive load demands high levels of concentration (focal-task engagement), which suppresses peripheral processing and therefore decreases distraction. In this article, we employed an functional magnetic resonance imaging (fMRI) protocol to explore whether higher cognitive load in a visually-presented task suppresses task-irrelevant auditory processing in cortical and subcortical areas. The results show that selectively attending to an auditory stimulus facilitates its neural processing in the auditory cortex, and switching the locus-of-attention to the visual modality decreases the neural response in the auditory cortex. When the cognitive load of the task presented in the visual modality increases, the neural response to the auditory stimulus is further suppressed, along with increased activity in networks related to effortful attention. Taken together, the results suggest that higher cognitive load decreases peripheral processing of task-irrelevant information—which decreases distractibility—as a side effect of the increased activity in a focused-attention network.

Constraints on dilution from a narrow attentional zoom reveal how spatial and color cues direct selection

Distractor interference is subject to dilution from other nontarget elements, and the level of dilution is affected by attention. This study explores the nature of dilution when the location and color of the target is known in advance. Experiments 1 and 2 show that attention is effectively limited to the precued region, so that it is the nontarget letters appearing at the cued locations that are responsible for most of the dilution, and not those appearing at the uncued locations. Furthermore, this dilution occurs relatively early in processing. Experiment 3 demonstrates that top-down attentional control can prevent dilution, because foreknowledge of the target color leads to quick attention shifts. Experiment 4 illustrates bottom-up attentional control in preventing dilution when the distractor is a color singleton that is segregated from the diluting nontargets. The results show that dilution is modulated by both top-down and bottom-up factors, that it can occur even when attention is restricted to a relatively small region, and that it occurs early in processing, but not so early that it avoids the effects of attention. They provide new challenges for earlier accounts suggesting that dilution is widespread and unfettered by attention. Likewise, some parts of the results are difficult to reconcile with the alternative perceptual load theory, but they do support a form of dilution that is limited by attentional boundaries. Because of that link to attention, dilution is a useful tool for measuring how attention is guided by information about target location and color.