Intraparietal stimulation disrupts negative distractor effects in human multi-alternative decision-making.

Area of Science:

• Cognitive Neuroscience
• Decision Science

Background:

• The influence of irrelevant distractors on binary decision-making remains debated.
• Existing models propose conflicting effects of distractors on choice accuracy.

Purpose of the Study:

• To reconcile opposing views on distractor effects in decision-making.
• To investigate the coexistence and interplay of positive and negative distractor effects.
• To determine the neural basis of distractor influence using transcranial magnetic stimulation (TMS).

Main Methods:

• Human participants performed decision-making tasks with varying distractor values.
• Transcranial magnetic stimulation (TMS) was used to disrupt the medial intraparietal area (MIP).
• Correlation analysis between MIP volume and susceptibility to TMS-induced disruption was performed.

Main Results:

• Both positive (improving decisions) and negative (decreasing accuracy) distractor effects were observed.
• The dominance of each effect varied across the decision space.
• Disruption of MIP via TMS enhanced positive distractor effects while reducing negative ones.
• Larger MIP volumes correlated with reduced susceptibility to TMS-induced disruption.

Conclusions:

• Human decision-making incorporates both positive and negative distractor effects, dependent on context.
• The medial intraparietal area (MIP) plays a causal role in modulating these distractor effects.
• Findings support a divisive normalization mechanism underlying distractor influence in decision-making.