Dual-tasking modulates movement speed but not value-based choices during walking

Area of Science:

• Cognitive Neuroscience
• Human Motor Control
• Decision-Making Science

Background:

• Value-based decision-making integrates reward and cost, often in complex, real-world multitasking environments.
• Laboratory studies typically isolate cognitive and motor processes, potentially missing crucial interactions.
• Existing models suggest reward processing is capacity-limited, while motor cost is not.

Purpose of the Study:

• To investigate how dual-tasking affects the interplay of reward and motor costs in value-based decision-making.
• To test the hypothesis that added cognitive load primarily impairs reward processing, not motor cost influence.
• To explore potential motor-cognitive interactions during complex decision tasks.

Main Methods:

• A real-time decision-making task where participants chose to walk towards targets for rewards, with variable motor costs (obstacle navigation).
• Participants performed the task under single-task (decision-making only) and dual-task (decision-making plus pitch-recall) conditions.
• Analysis focused on how reward magnitude, motor cost, and dual-tasking affected choice behavior and walking speed.

Main Results:

• Both reward value and motor cost significantly influenced participants' decisions.
• The introduction of a secondary cognitive task did not differentially impair the processing of reward or motor cost.
• Dual-tasking led to a significant reduction in walking speed, decreasing the overall reward rate.

Conclusions:

• Contrary to predictions, cognitive load in a dual-task scenario did not alter the valuation of reward or motor cost.
• Motor-cognitive interactions manifest as a general slowdown in motor execution (walking) rather than altered cost-benefit analysis.
• Findings suggest interference at the locomotor control level, highlighting the interconnectedness of motor and cognitive systems in decision-making.