Increasing Working Memory Load Reduces Processing of Cross-Modal Task-Irrelevant Stimuli Even after Controlling for Task Difficulty and Executive Capacity

Abstract

The classic account of the load theory (LT) of attention suggests that increasing cognitive load leads to greater processing of task-irrelevant stimuli due to competition for limited executive resource that reduces the ability to actively maintain current processing priorities. Studies testing this hypothesis have yielded widely divergent outcomes. The inconsistent results may, in part, be related to variability in executive capacity (EC) and task difficulty across subjects in different studies. Here, we used a cross-modal paradigm to investigate whether augmented working memory (WM) load leads to increased early distracter processing, and controlled for the potential confounders of EC and task difficulty. Twenty-three young subjects were engaged in a primary visual WM task, under high and low load conditions, while instructed to ignore irrelevant auditory stimuli. Demands of the high load condition were individually titrated to make task difficulty comparable across subjects with differing EC. Event-related potentials (ERPs) were used to measure neural activity in response to stimuli presented in both the task relevant modality (visual) and task-irrelevant modality (auditory). Behavioral results indicate that the load manipulation and titration procedure of the primary visual task were successful. ERPs demonstrated that in response to visual target stimuli, there was a load-related increase in the posterior slow wave, an index of sustained attention and effort. Importantly, under high load, there was a decrease of the auditory N1 in response to distracters, a marker of early auditory processing. These results suggest that increased WM load is associated with enhanced attentional engagement and protection from distraction in a cross-modal setting, even after controlling for task difficulty and EC. Our findings challenge the classic LT and offer support for alternative models.

Combined assessment of attentional reserve and cognitive‐motor effort under various levels of challenge with a dry EEG system

“…Consequently, a reduction in the attentional resources available to allocate to taskirrelevant stimuli would occur. This notion is consistent with numerous studies that have proposed that working memory (and possibly the central executive) influences the degree to which attention is allocated to task-relevant information (here, Tetris) versus irrelevant information (here, auditory probes; Ishi et al, 2014;SanMiguel et al, 2008;Scheer et al, 2016;Simon, Tusch, Holcomb, & Daffner, 2016).…”

Increased Early Processing of Task-Irrelevant Auditory Stimuli in Older Adults

“…Our findings raise the possibility that in cross-modal tasks, increased cognitive load of the primary visual task may influence distracter processing in a manner that is similar to increased perceptual load in unimodal tasks. An alternative hypothesis is that the high load condition may elicit stronger attentional engagement in the primary task, marshalling greater recruitment of top-down control activity that limits the processing of irrelevant stimuli in the unattended channel [81–85]. Additional research is necessary to test these competing hypotheses.…”

Attention toward contexts modulates context-specificity of behavior in human predictive learning: Evidence from the n-back task

“…Previous research provided evidence that the working memory load related to the n-back task induces changes in attention deployment (e.g., Rose et al, 2005;Simon et al, 2016). However, an application of these findings to the present experiment should be made with caution, as there are several procedural differences between the n-back task from the present experiment and those used in the previous studies (e.g., number of stimuli, presence and type of additional tasks).…”

“…In this kind of task, participants are presented with a sequence of stimuli and are requested to indicate whether the current stimulus matches the stimulus shown n trials before. Evidence suggests that working memory load induced by the n-back task can reduce processing of task-irrelevant stimuli (e.g., Rose, Schmid, Winzen, Sommer, & Büchel, 2005;Simon, Tusch, Holcomb, & Daffner, 2016).…”