Technology that is designed to change attitudes or behaviors of the users through persuasion and social influence, but not through coercion.
Baxter received tons of great examples, here are a few highlights:
Manicare Stop is a nail polish with a bitter taste. The very fact that it's bitter forces people to change their behavior of biting their nails.
Ford Fusion's dashboard with eco leaves is the dashboard on all new Ford Fusions encouraging eco-friendly driving. If a driver wastes gas by aggressively accelerating or slamming on the brakes the vine withers and leaves on the dashboard disappear. More leaves appear if individuals drive more economically.
ReadyForZero - are stickers that go on your credit card which remind you not too spend too much. As you look at your credit the very existence of that sticker on top of it changes your behavior to buy something.
Armed with these great examples Baxter goes on to argue that the UX field is playing catch up when it comes to persuasive technology. Marketing and advertising industries have studied, tested, and honed the art of influencing people's behavior for decades while the UX field, he says, is only beginning to play around with persuasive design:
UX practitioners are designing persuasive technologies every day, but are only beginning to formalize the education, ethics, and metrics behind creating them. Without such structure, we will continue to see cargo cults that inappropriately use techniques, such as gamification. Foursquare, Gowalla, and other services popularized the use of game mechanics to drive user engagement. Unfortunately, many companies have strictly copied the obvious game elements, such as badges and leveling-up, without understanding the deeper psychology at work. These services have seen the power of persuasive design, but lack a true understanding of how to properly apply psychology in UX design.
Baxter is right in saying that the websites which are starting to experiment with persuasive design are just scratching the surface and have a lot to learn. Embracing this type of design will be the next big step in pushing the UX field forward.