Volunteers Trained to Scream for Ice Cream

British scientists who trained human volunteers to react like Pavlov’s dogs to peanut butter and ice cream reported in this week’s issue of Science that their brain scans help explain why we fill up on dinner yet have room for dessert.

The volunteers were conditioned to become hungry when they saw certain abstract pictures, just as Pavlov’s dogs salivated at the sound of a bell, the researchers said. The scientists found that repeated exposure to images associated with food triggered desire for that food, but the desire was smaller if the food had been consumed recently.