humans than any other animal. when your prefrontal cortex works right, and it's not fully developed until we're about 25 years old, when it's weak, it's like the supervisor in your head is taking a break. then your inner child, who's having tantrums, or who wants the crack cocaine or wants the third piece of cheesecake, if your prefrontal cortex is not right, nothing in your life is going to be right. so head injuries matter, low blood sugar matters. you don't eat breakfast, you're going to make bad decisions about food the rest of the day. if you don't sleep right, lower blood flow to the brain. >> larry: doesn't that defy, dr. pratt, that when you're 4 years old, you know everything about yourself then? >> when we're 4, actually, when we're talking about will power, or want power, we have a conscious and subconscious mind. if we didn't -- it's called