Task-evoked pupil responses reflect internal belief states

Area of Science:

• Neuroscience
• Cognitive Science
• Computational Neuroscience

Background:

• Internal uncertainty signals are crucial for regulating learning and decision-making.
• The brain's arousal systems are increasingly implicated in signaling uncertainty.
• Pupil diameter serves as a peripheral marker of central arousal states.

Purpose of the Study:

• To investigate how computational variables related to uncertainty modulate arousal during perceptual decision-making.
• To examine the relationship between pupil responses, decision confidence, and prediction errors.
• To test if arousal modulation reflects internal belief states.

Main Methods:

• Subjects performed a challenging perceptual choice task with delayed monetary reward.
• Pupil diameter was monitored as a measure of arousal.
• Computational variables, including decision confidence and prediction errors, were quantified.

Main Results:

• Pupil responses were modulated by decision difficulty and accuracy.
• Pupil responses negatively scaled with decision confidence before feedback.
• Pupil responses scaled with uncertainty-dependent prediction errors after feedback.

Conclusions:

• Pupil-linked arousal systems are modulated by internal belief states during perceptual decision-making.
• Arousal boosts are evoked by decision confidence and prediction errors at different stages.
• These findings support models where graded beliefs about choice accuracy influence reward anticipation and error computation.