PITTSBURGH—As you walk down a busy city street, there might be a number of objects lying on the ground that you don’t even notice. But if one of them were a $20 bill you most likely would see it and pick it up, and if another were a snake you most likely would see it and swerve. These things happen because of neurons in your parietal cortex.

In a study published in the Oct. 5 issue of Science, researchers from the Center for the Neural Basis of Cognition, a joint program between Carnegie Mellon University and the University of Pittsburgh, demonstrated that neurons in the lateral intraparietal area (LIP) respond strongly to very good objects (like the $20 bill) and very bad objects (like the snake). They call out to the rest of the brain: “pay attention to this.” They leave it to other brain areas to decide whether “this” is good or bad.