How Do We Cooperate?

Ernst Fehr, a neuroeconomist, studies the brain and human behavior. Specifically, he conducts experiments to examine how changing levels of neural activity in the brain affect “norm compliance.” Fehr employs “transcranial direct current stimulation”; that is, using a cathode and an anode, he applies a current – so gentle that subjects don’t feel it – to the “right dorsolateral prefrontal cortex.” If he places the cathode on the area, he can “down-regulate” neural activity; if he places the anode on that spot, he can “up-regulate” neural activity. This manipulation alters subjects’ tendency to comply with social norms.

In ...