Motor response vigour and visual fixation patterns reflect subjective valuation during intertemporal choice

Area of Science:

• Cognitive Neuroscience
• Neuropsychology
• Decision Science

Background:

• Value-based decision-making is crucial in cognitive neuroscience and psychology.
• Impaired decision-making is a hallmark of neuropsychiatric disorders.
• Traditional studies focus on explicit choices, but implicit measures like motor vigour and eye movements may also reflect subjective utility.

Purpose of the Study:

• To investigate the relationship between motor response vigour, visual fixation, and option valuation in intertemporal choice.
• To explore how implicit measures of subjective utility correlate with computational models of decision-making.

Main Methods:

• Participants performed an intertemporal choice task involving grip force exertion and eye-tracking.
• Hierarchical Bayesian parameter estimation was used to model choices with hyperbolic discounting.
• Drift diffusion models were compared, assessing the link between response vigour and model parameters.

Main Results:

• A drift diffusion model with non-linear drift rate scaling by subjective value differences best explained the data.
• A magnitude effect in temporal discounting was observed (higher rewards discounted less), mirrored in motor response vigour.
• Higher subjective value differences correlated with increased grip force, faster response times, and fewer fixation shifts.

Conclusions:

• Subjective utility and implicit valuation are reflected in motor response vigour and visual fixation patterns during intertemporal choice.
• Incorporating response vigour can enhance understanding of decision-making, reward valuation, and related disorders.