Neural dynamics of predicted decisions for similar and dissimilar others

Although brain regions related to option valuation are engaged in both decisionsfor oneself and when predicting the decisions of others, additional neural mechanismsdifferentiate the agent for whom the decision is being made. However, much less isknown about the temporal relationship of valuation and self-other distinction within asingle decision and whether one precedes the other, particularly in contexts where theself-other similarity is quantified and controlled. In the present preregistered study, 54human participants (10 male, 40 female) first completed risky decisions for themselves;we then used their estimated risk preference to simulate choices of two other agents -one with a similar, one with a dissimilar risk preference - whose preference participantslearned to then predict their decisions. Analysing the ERP data from the three typesof decisions (self decisions; similar predictions; dissimilar predictions) revealed a latefronto-centro-parietal effect of decision difficulty (approx. 800 - 1000ms post-stimulus),which did not vary across decision types. In addition, we identified an earlier centroparietal component which distinguished similar predictions from self decisions (approx.550 - 800ms post-stimulus). Intriguingly and contrary to our hypothesis, no signal differentiating dissimilar predictions from self decisions was found. A classification analysisbetween the decision type pairs confirmed that similar predictions were more differentiable from self decisions than dissimilar predictions were. Altogether, our findingssuggest that the brain first identifies the agent of the decision early in the trial (particularly if preferences could be confused with one’s own), followed by a domain-generalvaluation process.