Using response time modeling to understand the sources of dual-task interference in a dynamic environment.

Strayer, David L.; Heathcote, Andrew · 2019 · Journal of Experimental Psychology Human Perception & Performance

DOI: 10.1037/xhp0000672

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Summary

This study investigates the cognitive mechanisms underlying dual-task interference in dynamic, time-pressured environments, specifically testing whether such interference stems from competition for limited information-processing resources. While resource-sharing theories posit that individuals reallocate capacity from secondary to primary tasks under high load, previous empirical support has been ambiguous because behavioral metrics like response time and accuracy can result from various cognitive processes, including changes in response caution, bias, or non-decision times. To resolve this, the authors applied evidence-accumulation modeling to disentangle these latent processes. The experimental design involved 66 participants divided into single-task and dual-task groups. The primary task was a simulated maritime surveillance classification task where participants identified target versus non-target ships under varying levels of time pressure, manipulated by changing the number of ships (2–4) and the deadline for classification (6, 9, or 12 seconds). The secondary task was the Detection Response Task (DRT), a standardized workload measure requiring participants to detect vibrotactile stimuli presented randomly every 3–5 seconds. The authors fitted the Wald evidence-accumulation model to performance data from both tasks. This model partitions response times into decision time (governed by the rate of evidence accumulation and response threshold/caution) and non-decision time (sensory encoding and motor production), allowing for precise quantification of how time pressure affects specific cognitive components. Behavioral results indicated that participants prioritized speed over accuracy as time pressure increased, leading to higher error rates and non-response rates, particularly for target stimuli. Perceived workload was significantly higher in the dual-task group. Crucially, the model-based analysis revealed distinct patterns for the two tasks. For the primary classification task, increased time pressure led to an increased rate of evidence accumulation and decreased response caution, indicating a strategic shift to process information faster with less deliberation. Conversely, for the secondary DRT, the rate of evidence accumulation declined under greater time pressure, while response caution remained relatively stable or increased slightly. These findings demonstrate that as primary task demands increased, the rate of information processing for the secondary task decreased. The significance of these findings lies in their support for resource-sharing theories of workload. By showing that the rate of evidence accumulation—a proxy for allocated cognitive capacity—increased for the primary task and decreased for the secondary task under time pressure, the study provides direct evidence that dual-task interference is driven by the reallocation of limited processing resources. This validates the use of the DRT as a sensitive measure of workload, as it captures the diversion of resources away from secondary monitoring tasks. Furthermore, the study highlights the necessity of using cognitive modeling rather than behavioral metrics alone to accurately identify the sources of performance decrements in complex, safety-critical environments.

Key finding

Under greater time pressure, the rate of information processing increased for the primary task while response caution decreased, whereas the rate of information processing for the secondary task declined.

Methodology

lab_experiment

Sample size: 66

Provenance

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Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.

Topics

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• dual task performance
• dual task multitasking
• time perception
• mental demand

Information type

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• Empirical Findings: behavioral performance data
• Theoretical Contribution: theory or model