Abstract
Context effects have been explained by either high-level cognitive processes or low-level neural adjustments but not their combination. Therefore, it is unclear how these processes interact to shape individuals’ responses to context. Here, we used a large cohort of human subjects in experiments involving choice between two or three gambles in order to study the dependence of context effects on neural adaptation and individuals’ risk attitudes. We found no evidence that neural adaptation on long timescales contributes to context effects. However, we identified two groups of subjects with distinct patterns of responses to decoys that depended on individuals’ risk aversion. Subjects in the first group exhibited strong, consistent decoy effects and became more risk averse due to decoy presentation. In contrast, subjects in the second group did not show consistent decoy effects and became more risk seeking. Interestingly, the degree of change in risk aversion due to decoy presentation was positively correlated with the initial degrees of risk aversion. To explain these results and reveal underlying neural mechanisms, we developed a new model that incorporates both low- and high-level processes to fit individuals’ choice behavior. We found that observed decoy effects can be explained by a combination of adjustments in neural representations and competitive weighting of reward attributes, both of which depend on risk aversion but in opposite directions. Altogether, our results demonstrate how a combination of low- and high-level processes shapes multi-attribute choice, modulates overall risk preference, and explains distinct behavioral phenotypes.
Acknowledgments
We thank Daeyeol Lee and Chanc VanWinkle Orzell for helpful comments on the manuscript.
Footnotes
Conflict of interest: The authors declare no competing interests.