A question is how do people decide how to share resources? This is important for inequality. Imagine you have three choices:
‘Self’ represent money delivered to yourself, whereas ‘Other’ represents money given to another random person whom you do not know and you never meet. Your preferences over the three outcomes represent your social preferences (formally called Social Value Orientation): selecting the first options will mean that you are a cooperative person (you want to maximise the total sum); the second makes you individualistic (you only care for what you get); and the third makes you competitive- you want to mazimize the difference with the other person. Note that a competitive person is willing to get less money provided the difference with the other person also increases (we all know some of these Donalds – uuups).
This can be more formally represented in a cartesian space:
This is what we found when we did the study (mind you at Texas):
In fact most people in our sample are individualists. But what are the neural correlates? The basic finding is that the brain separates $ delivered to self and $ delivered to other:
The bars below the brains indicate four different experiments all identifying the very same areas responding to self and other respectively.
Now you might ask: is the $ delivered to the other person represented in the same way for competitive and cooperative persons? It should not! And, indeed, the area (MPFC) responds in a different way depending on whether you are competitive or cooperative:
How do we interpret this signal? We believe that MPFC has a general function to signal a violation of our social preferences: MPFC is activated when a cooperative outcome is delivered only if you are competitive person; respectively, if you are cooperative, MPFC signals the competitive outcome.