Because we included offers such as $5 out of $23, we could also look at something new that Sanfey could not. This offer is unfair, but to the typical college undergraduate it is a financially desirable proposition ($5 is the maximum reward in most neuroscience ultimatum game studies). Rejecting $1 out of $10 is easy, but $5 out of $23 is a different story. There are at least two things that might be going on when people accept these unfair but desirable offers. On the one hand, the pure reward potential might be highly motivating. In this case, one would expect to see more activity in reward regions like the ventral striatum when accepting $5 out of $23 compared to when they reject these offers. We did not see any evidence for that.
Alternatively, this could be a case of self-control, in which people may say to themselves “that may be an insulting offer, but if I resist the temptation to get revenge, I can leave with more money.” Although our data can’t establish whether subjects actually thought something like that, the data were certainly consistent with that kind of process. When people accepted these offers, we saw increased activity in right inferior prefrontal cortex (a region involved in various forms of self-control), decreased activity in the insula, and an inverse relationship between the regions such that greater prefrontal activity was associated with diminished insula activity. This [finding] is consistent with the idea that people are regulating their distress in order to achieve the long-term financial benefit. One interesting implication of this is that it suggests our impulse is to reject unfair treatment rather than to get the money and that it is our cognitive abilities that lead us to accept, rather than to reject, the unfair treatment and take the money.
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