Strategy-dependent effects of working-memory limitations on human perceptual decision-making

Area of Science:

• Cognitive Neuroscience
• Decision Science
• Human Psychophysics

Background:

• Deliberative decision-making relies on accumulating evidence over time, a process dependent on working memory.
• Working memory has inherent limitations, but their specific impact on deliberative decision-making remains unclear.

Purpose of the Study:

• To investigate how working memory limitations affect the fidelity of continuous decision variables during evidence accumulation.
• To understand the neural and cognitive constraints on maintaining and computing dynamic decision variables.

Main Methods:

• Human psychophysics experiments were conducted to assess the impact of working memory capacity and time on decision variable fidelity.
• Participants performed a task requiring them to decide the average location of multiple visual targets.

Main Results:

• The fidelity of the computed, continuous decision variable degraded over time and with reduced working memory capacity.
• This degradation was critically dependent on the strategy used to compute the decision variable.
• Different memory storage strategies (immediate single-value vs. late multi-value) led to distinct patterns of degradation.

Conclusions:

• Working memory limitations impose significant constraints on the brain's ability to compute and maintain temporally dynamic decision variables.
• The strategy for storing evidence in working memory (as a single or multiple values) critically influences decision fidelity.
• Findings provide insights into the neural mechanisms underlying evidence accumulation and decision-making under capacity constraints.