One more example to get you thinking about motivation and design and then we'll go on to the psychological theories in more detail. So, let's say you want to motivate people to buy computers. You can make really good computers. Okay. Check. You can price the computers afford ably. Okay. Check. But, if you're going to create a retail experience, let's say, what would motivate those people to buy more computers in the retail store? You might think that the answer would be, make it really efficient, make it quick, make it easy, so that people can see all the products, they're all together in one place. They can compare them and decide what they want to buy and get out of there. That's how most computer stores worked until along came the Apple Store. And the Apple Store looked at this very differently. The Apple Store said, or I guess Apple said, in building the Apple Store, no, what we want is for people to come in and hang around and browse. This is an expensive purchase and it's a lifestyle purchase. We want people to get familiar with how to use our computers. People often don't buy computers because they don't really know how they work or what they would do with them. So, let's create a kind of lounge experience where people can hang around. It's comfortable, you can see all the products and they're beautifully displayed and there's lots of them you can play around with. And we'll stock it with a whole bunch of helpful people who aren't necessarily sales people, they're just there to help you and explain stuff and take you around. Or, if you have a computer and you've got problems, we'll create a genius bar there. We'll have classes and other sorts of things. We'll make this a place, not that you want to get out of quickly, but a place you want to linger. Because the more you linger, the more time you spend with the products, the deeper you get into what you could do with these products, and at the end of the day the more you'll buy. Apple store is the highest grossing retail chain in the entire United States. So, Apple was able to successfully motivate people to buy their products, by thinking differently about how to design stores. And, this is clearly not an example of gamification. But it's a useful thought experiment for gameified systems to think about how do we do the same kind of things that Apple did for the situation that we're involved in. It's not that making people linger in a lounge like environment is always the right answer. The point is, thinking about users, different ways to motivate them. And the nature of the task at hand gets us thinking creatively about how to deploy motivation in a systematic way, and that's what we're going to look at now in gamification.