Genetic influence on our valuation of free choice

Cockburn et al. find an interesting correlation: A polymorphism in DARPP-32, a gene linked to dopaminergic striatal plasticity and individual differences in reinforcement learning, predicts how strongly people exhibit preference for options they have freely chosen over equally valued options they have not. Here is their abstract, along with a statement of highlights:

 Highlights

Participants exhibit a biased preference for freely chosen rewarding options

DARPP-32 genotype predicts choice bias as a function of expected value

Bias is mirrored by a model that amplifies positive free-choice learning signals

Choice bias is the byproduct of a mechanism that refines learning signal fidelity

Summary

Humans exhibit a preference for options they have freely chosen over equally valued options they have not; however, the neural mechanism that drives this bias and its functional significance have yet to be identified. Here, we propose a model in which choice biases arise due to amplified positive reward prediction errors associated with free choice. Using a novel variant of a probabilistic learning task, we show that choice biases are selective to options that are predominantly associated with positive outcomes. A polymorphism in DARPP-32, a gene linked to dopaminergic striatal plasticity and individual differences in reinforcement learning, was found to predict the effect of choice as a function of value. We propose that these choice biases are the behavioral byproduct of a credit assignment mechanism responsible for ensuring the effective delivery of dopaminergic reinforcement learning signals broadcast to the striatum.