Groupthink: "a mode of thinking that people engage in when they are deeply involved in a cohesive group, when the members' strivings for unanimity override their motivation to realistically appraise alternative courses of action" [via kottke]. Consider, if your brain is a highly cohesive group of with different incentive operating in different places, isn't groupthink the same process you undergo as an individual? Once the decision is made (because the brain has to decide) it's more difficult to see alternatives?