Now, variables rewards we see in lots of situations and probably the most powerful example of a variable reward machine is this thing, the one arm bandit. The slot machine. It's about tangible rewards. Those gold coins you get there. But, what makes he slot machine work. What makes the slot machine addictive to people, is the variable reward schedule. You never know when a reward is going to come up, and a good slot machine, or at least, an effective slot machine for the casino owner is tuned. So that the reward is variable. It's random. You can't be certain exactly when it's going to happen. But the reward comes just enough, so thatyou don't give up. You play, and play, and play. And most of the times, you pull the big handle and nothing happens. But then just before you're going to give up, you get something.You get a little jackpot. And every once in a while someone in thecasino gets a big jackpot. So the idea is, it's a variable schedule, a random uncertain reward. But it's tuned so that it happens frequently enough, so that the person who's playing holds outthat hope. If I just pull the handle a few more times, put in a few more coins. Then I'm going to hit the jackpot, and that's the essence of what makes slot machines, for at least some people really addicting. Now, I will emphasize, as I have before, that this is not entirely a good thing. Addicting people is something that is dangerous and potentially harmful to them. And while we throw around sometimes ingamification and marketing things like we want to get our customers addicted, it's important to distinguish that from truly getting them to the point where they don't know what they're doing and can't make good judgments. And as we'll see, as we get into the next section. There's some real danger of going down this behavioral path of focusing entirely on how people respond to stimuli that we put in front of them.