“Imagine there’s a marshmallow sitting on a plate in front of you. A nice lady in a lab coat sits next to you. She says she’s going to leave the room, and you can eat the marshmallow if you want. But if you wait for her to get back, she’ll give you two marshmallows. Oh and by the way, you’re only four years old in this scenario. So which is it: one marshmallow now or two later? Choose wisely. It may impact the rest of your life. This famous experiment was conducted over forty years ago. Kids who waited to get the second marshmallow grew up to be more successful than kids who ate the one in front of them right away. They had higher SAT scores, were more likely to go to college, and were less likely to use drugs.8 The marshmallow experiment is really a test of your prefrontal cortex’s serotonin function and its ability to override the habitual and impulsive striatum. In fact, when the kids from the original marshmallow experiment were scanned in an fMRI forty years later, they even had differences in prefrontal activity.9 The ones who had waited for the marshmallow as four-year-olds had greater ventrolateral prefrontal activity, which, unsurprisingly, helps control impulses.”