Having More Choices Changes How Human Observers Weight Stable Sensory Evidence

Area of Science:

• Cognitive Neuroscience
• Decision Sciences
• Human Perception and Action

Background:

• Increased choice options often lead to slower decision-making.
• Previous models proposed sensory processing deficits, reduced evidence accumulation, or higher decision thresholds as causes.
• Prior research often confounded choice number with task difficulty and attention demands.

Purpose of the Study:

• To isolate the neural effects of increased choice number on sensory and decision-making processes.
• To differentiate the impact of choice load from attentional demands and task difficulty.
• To elucidate the specific mechanisms underlying choice-induced decision-making slowdown.

Main Methods:

• Utilized electroencephalography (EEG) to measure steady-state visually evoked potentials (SSVEPs) and frontal late positive deflection (LPD).
• Controlled task difficulty while independently manipulating the number of choices and attentional distribution.
• Recorded neural responses from male and female human observers performing decision tasks.

Main Results:

• Dividing attention decreased both SSVEP and LPD amplitudes, indicating dampened sensory responses and slower evidence accumulation.
• Increasing the number of choices did not alter SSVEP amplitude, suggesting preserved early sensory processing.
• A larger LPD was observed with more choices, indicating a selective increase in decision thresholds.

Conclusions:

• The number of choices primarily affects later, postsensory decision-making stages rather than early sensory perception.
• Decision-making slows with more options due to a selective elevation of the decision threshold.
• Findings challenge models solely attributing choice-induced slowing to sensory or evidence accumulation deficits.