Social competition factor influences the neural response to rewards: an ERP study

To study if the neural system responds the same or differently to the same rewards in different social competition conditions, event-related brain potentials (ERPs) were recorded as 18 participants engaged in two kinds of decision tasks. In the auction condition (the competition condition), participants were instructed to bid against their competitors and then informed the outcome (failing and gaining no money, or winning and gaining a certain amount of money); in the lottery condition (the neutral condition), subjects were asked to play a lottery against the computer and then informed the outcome (the same as in auction). Scalp ERPs revealed that, in the outcome phase, failing (rewards=0) in auction induced a larger late positive complex response (in the time window of 700-1200ms) than that in lottery; while winning (rewards>0) in lottery induced a larger late positive complex response (in the time window of 500-800ms) than that in auction. The present data suggest, when evaluating rewards, our neural systems care about not only rewards themselves, but also how the rewards have been obtained.