Differentiating between Models of Perceptual Decision Making Using Pupil Size Inferred Confidence

Area of Science:

• Neuroscience
• Cognitive Science
• Decision Making

Background:

• Perceptual decisions often show a bias towards early sensory evidence.
• This early weighting is commonly explained by integration-to-bound models where evidence accumulation stops upon reaching a confidence threshold.

Purpose of the Study:

• To derive predictions on temporal evidence weighting based on decision confidence within integration-to-bound models.
• To empirically test these predictions using pupil size as a proxy for decision confidence in non-human primates.

Main Methods:

• Developed a method to infer decision confidence from pupil diameter in male macaques.
• Monkeys performed a disparity discrimination task to collect behavioral and physiological data.
• Compared empirical data against predictions from integration-to-bound models and alternative theories.

Main Results:

• Animal data supported the predictions of the integration-to-bound decision process.
• Individual differences in decision bounds and pupil-confidence correlations explained variations between subjects.
• Alternative models, including attractor dynamics and neuronal adaptation, were less compatible with the findings.

Conclusions:

• The integration-to-bound model provides a robust explanation for early psychophysical weighting in perceptual decision-making.
• Pupil size serves as a viable, non-invasive measure of decision confidence in neurophysiological studies.
• This approach facilitates broader investigations into the neural basis of confidence and metacognition.