Project 3: Processing Other People's Rewards. A. Rangel, PI

Many decisions are driven by how much a decision-maker values his or her reward personally, but we also routinely have to take account of rewards that benefit others or in anticipation of which we can attempt to manipulate others.  Examples include sacrificing food for a child, giving a donation to charity, or quoting a price for a sale to somebody.  In all these cases, we need to represent how another person would value a certain outcome and direct our behavior accordingly.  Such an ability, related to “theory of mind”, is essential for successful social functioning and features pronounced individual differences.  Very little is as yet known about its neural substrates.

Project 3 will investigate how the value of rewards for self and other are encoded at time of decision making and at the time of obtaining the outcome, through fMRI and the superior resolution of single unit and local field potential (LFPs) measures in both monkeys and human epileptic patients. Do single neurons in the same areas specialize in computing either self or other components of value? Is there any fine-grained anatomical segregation of self- and other-value representations? Single unit and LPFs will be recorded in amygdala and prefrontal cortex in both humans and monkeys.

This project also investigates how the self and other decision-making and outcome signals in the areas of interest are modulated by three basic social context variables: (1) social distance, which is manipulated by carrying out experiments with other people varying in familiarity; (2) social deservingness of the other, which is manipulated by providing information about the level of pro-social behavior of the other in a charitable giving task; (3) social reputation of oneself, which is manipulated by the presence of an audience that has no direct impact on outcomes (other people watching what you choose for yourself, or what you choose to benefit another person).

Finally, Project 3 investigates individual differences in “self” and “other” decision and outcome coding. This aspect of the project once more takes advantage of the large sample size in the human fMRI experiments to look for systematic individual differences in the encoding of other- decision and outcome signals across gender, age, and other trait variables such as empathy, IQ, and emotional intelligence.  We expect that  there will be systematic relationships between them and the strength with which the brain encodes the value signals for others.