The psychologists asked a group of random students to choose between a pair of Amazon.com gift vouchers. If they picked the first, a $15 gift voucher, they would get it at once. If they were willing to wait two weeks for the $20 gift certificate, well, obviously they’d be getting more bang for their buck. The brain scans revealed that both gift options triggered activity in the lateral prefrontal cortex, the area of the brain that generates emotion. But the possibility of getting that $15 gift certificate now! caused an unusual flurry of stimulation in the limbic areas of most students’ brains-a whole grouping of brain structures that’s primarily responsible for our emotional life, as well as for the formation of memory.