Methods

20-30 normal, healthy individuals will be recruited from the local community. The experiment will be performed in the 3.0 Tesla X750 GE Discovery MRI scanner at the Waisman Laboratory for Brain Imaging and Behavior at the University of Wisconsin-Madison. In the scanner, subjects will be presented with a series of opportunities for selfish reward and altruistic giving, similar to the procedure in Harbaugh et al.(2007), but using an individual recipient rather than an organization, to encourage a perception that the self and other are at similar points in their subjective utility curves. Each trial will consist of presentation of transfer package; a decision to accept or reject the transfer; and a presentation of the outcome. Transfer packages will span a range of positive and negative values to the subject, and positive and negative values to the other. Analysis of subject choices to accept and reject different transfers will …