Studies of the snap judgments we often make about people are shedding new light not only on social behavior, but also on drug abuse, gambling addiction, and other disorders in which our ability to make decisions is impaired, say scientists at the California Institute of Technology.

An emotional decision, such as forming an immediate like or dislike upon a first encounter with a new person, often occurs abruptly and automatically-and that impression can be difficult to change. To decipher the neurological underpinnings of those decisions, which will help explain the unique neurological characteristics of emotion, Hackjin Kim, a former postdoctoral scholar at Caltech who is now an assistant professor at Korea University--along with Ralph Adolphs, a professor of psychology and neuroscience, John O'Doherty, an associate professor of psychology, and Shinsuke Shimojo, a professor of biology--used a novel technique to monitor the activation of two brain regions during decision-making tasks.