Separation of Tasks Into Distinct Domains, Not Set-Level Compatibility, Minimizes Dual-Task Interference

Halvorson, Kimberly M.; Hazeltine, Eliot · 2019 · Frontiers in Psychology

DOI: 10.3389/fpsyg.2019.00711

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Summary

This study investigates the mechanisms underlying reduced dual-task interference, specifically testing whether "set-level compatibility" or the separation of tasks into distinct sensory domains minimizes performance costs. Previous research indicated that dual-task costs are negligible when tasks use compatible stimulus-response (S-R) pairs, such as visual-manual and auditory-vocal tasks. Two competing explanations existed: the spatial-verbal hypothesis, which posits that separating tasks into distinct spatial and verbal domains prevents interference, and the set-level compatibility hypothesis, which suggests that the general correspondence between stimulus sets and response sets (e.g., images of hands activating manual responses) is sufficient to reduce costs, regardless of specific item mappings. To distinguish between these accounts, Halvorson and Hazeltine employed a 2 × 2 experimental design manipulating compatibility at both the element level (Ideomotor, or IM) and the set level (Paramotor, or PM). Participants performed dual tasks involving visual-manual responses (pressing keys) and auditory-vocal responses (speaking words). In IM conditions, stimuli directly resembled the sensory consequences of the responses (e.g., seeing a hand press a key and pressing that same key). In PM conditions, set-level compatibility was maintained (hands mapped to keys; words mapped to speech), but element-level compatibility was removed. For the visual task, participants mapped hand shapes resembling the letters "V" and "W" to keys arbitrarily. For the auditory task, participants mapped color words ("red," "green") to animal names ("cat," "dog") arbitrarily, breaking the direct link between stimulus and response while maintaining the auditory-verbal domain. The results demonstrated that set-level compatibility alone was insufficient to minimize dual-task interference. Participants exhibited significantly larger dual-task costs in conditions involving PM tasks compared to those with IM tasks. Specifically, single-task reaction times were slower for PM tasks, and the interference observed when performing tasks concurrently was greater when the specific S-R mappings were not ideomotor-compatible. The data supported the spatial-verbal hypothesis, indicating that the ability to keep tasks separate by utilizing distinct processing domains (spatial vs. verbal) and direct element-level activation is critical for efficient dual-task performance. The findings conclude that dual-task costs are minimized not merely by the general compatibility of stimulus and response sets, but by the specific separation of tasks into distinct domains and the direct activation of response codes via ideomotor-compatible stimuli. This challenges theories relying solely on set-level activation and reinforces the importance of modality-specific processing and direct stimulus-response correspondence in understanding cognitive bottlenecks during multitasking.

Key finding

Separating dual tasks into distinct spatial and verbal domains minimizes interference more effectively than maintaining set-level compatibility between stimuli and responses.

Methodology

lab_experiment

Sample size: 60

Provenance

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Topics

Ranked by relevance to this paper. Hover a topic for its definition.

• dual task performance
• dual task multitasking
• task switching
• visual manual