Dual task interference on early perceptual processing

Duncan, Justin; Roberge, Amélie; Fortier-Gauthier, Ulysse; Fiset, Daniel; Blais, Caroline; Brisson, Benoit · 2021 · Crossref

DOI: 10.3758/s13414-020-02158-0

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Summary

This study investigates whether the psychological refractory period (PRP) effect—typically attributed to a central bottleneck in response selection—also interferes with early perceptual processing of a second target (T2). While classical models assume pre-bottleneck perceptual stages are immune to dual-task interference, prior evidence suggested otherwise, though those findings were confounded by shifts in visual-spatial attention, sensory modality, task type, and response modality. The authors aimed to isolate early perceptual interference by systematically removing these non-perceptual confounds across four iterative experiments. The researchers employed a dual-task paradigm where participants performed Task 1 (T1) followed by Task 2 (T2) with varying stimulus-onset asynchronies (SOAs). To specifically assess perceptual encoding success rather than response speed, T2 was briefly presented and immediately masked; T2 report accuracy served as the dependent variable. Experiment 1 ruled out visual-spatial attention shifts by comparing peripheral T2 presentations (requiring attention shifts) with central presentations. Experiment 2 eliminated sensory modality switching by using visual T1s instead of auditory ones. Experiment 3 addressed task switching, and Experiment 4 controlled for response modality switching. In all experiments, T2 duration was varied to prevent floor or ceiling effects, and participants were instructed to prioritize speed and accuracy for both tasks. The results demonstrated that T2 report accuracy significantly decreased as the SOA between T1 and T2 shortened, indicating interference at short intervals. Crucially, this decline in accuracy persisted across all four experimental conditions, even after visual-spatial attention shifts, sensory modality changes, task switching, and response modality switching were individually eliminated or controlled. For instance, in Experiment 1, significant PRP interference was observed in both peripheral and central conditions, with the effect actually appearing larger in the central condition where no spatial attention shift was required. Similarly, Experiment 2 showed that using a visual T1 did not abolish the SOA-dependent drop in T2 accuracy. These findings challenge the traditional view that the PRP effect is confined to central response selection stages. The authors conclude that central processing of T1 interferes with early perceptual encoding and visual short-term memory consolidation of T2. This suggests that multitasking costs extend to early sensory processing stages, not just later cognitive stages. The study implies that the mechanisms underlying the PRP effect and the attentional blink may share common roots, favoring an integrative approach to understanding multitasking deficits. This has significant implications for real-world scenarios requiring rapid responses to transient visual events, such as driving, where early perceptual interference could compromise safety.

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Topics

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• dual task multitasking
• dual task performance