Then one day, we’ll put the reward in the old place, and put in the rat, and, by golloy, the old habit will rememerge right away. habits never really disappear. They’re encoded into the sturctures of our brain, and that’s a huge advantage for us, because it would be awful if we had to relearn how to drive after every vacation. The problem is that your brain can’t tell the difference between bad and good habits, and so if you have a bad one, it’s always lurking there, waiting for the right cues and rewards.