Acute stress impairs reward positivity effect in probabilistic learning

Area of Science:

• Neuroscience
• Cognitive Psychology
• Decision Science

Background:

• Feedback learning involves cognitive processes like probability estimation and expectation modulation.
• Acute stress is known to affect decision-making and feedback processing, but its impact on reward expectancy remains unclear.

Purpose of the Study:

• To investigate the effect of acute stress on reward expectancy during probabilistic learning.
• To examine how stress influences brain responses, specifically the reward positivity (RewP), to reward prediction errors.

Main Methods:

• Participants completed a probabilistic learning task under stress (threat of shock) and safe conditions.
• Event-related potentials (ERPs) were recorded to measure the reward positivity (RewP) signal.
• Behavioral accuracy and the correlation between RewP and accuracy were analyzed.

Main Results:

• Behavioral performance was better in high (70%) versus low (30%) reward expectancy trials, with no overall difference between stress and safe conditions.
• Unexpected feedback elicited a larger RewP than expected feedback, but this effect was reduced under stress.
• A significant correlation between RewP and choice accuracy in the stress condition suggested blunted RewP was linked to impaired performance.

Conclusions:

• Acute stress alters brain responses to reward prediction errors, specifically reducing the RewP to unexpected feedback.
• The blunted RewP under stress may be associated with impaired individual-level performance in learning tasks.
• These findings offer neurophysiological insights into stress-related abnormal learning behaviors and disorders.