Dan Ariely is the James B Duke Professor of Psychology and Behavioral Economics at Duke University. He is the founder of The Center for Advanced Hindsight and co-founder of BEworks, which helps business leaders apply scientific thinking to their marketing and operational challenges. His books include Predictably Irrational and The Upside of Irrationality , both of which became New York Times best-sellers. as well as The Honest Truth about Dishonesty and his latest, Irrationally Yours .

Dan Ariely: There are lots of questions about how irrationality changes what we do. So, of course, we have demonstrations of people being irrational from time to time and the question is: How big is the impact on ourselves? And the answer is that it's really very large. There was just very sad analysis that looked at the question of what is the percentage of human mortality that is either aided by or caused by bad decisions? How often do we make a bad decision that either accelerates or kills us? And when you look at these results about 100 years ago, we say it's less than 10 percent. Think 100 years ago: How could you make a bad decision that would kill you? Not that easy but you could do it from time to time. Now, it's more than 40 percent. How come? What has changed? Technology. Over time we've invented technology that can kill us. So, of course, texting and driving is very clear; smoking, obesity. Some of those are single mistakes that can kill us like texting and driving, but some of those, like obesity, diabetes, and smoking are a series of mistakes that can kill us. And each of them is not that big, but together they accumulate.

And I think that's actually what happens. If you say what is the percentage of the decisions we make that are irrational? I don't know what the answer is. It's very hard to compute. But the fact is that those that we make are incredibly dangerous. You don't have to text and drive that many times to kill yourself. You don't have to start many habits in order to accelerate your death or to become incredibly unhealthy. So what happened is that the world around us is designed to tempt us. One of the principles from behavioral economics is choice architecture, the idea that when we are placed in an environment we make decisions as a function of the environment we're in. Think about the environment that we're in. What is it about? Is it about our long-term health or is it about the short-term profits of that environment? You walk down the street; there's a coffee shop. What does this coffee shop want? They want you to be healthy in 30 years from now or do they want you to buy another coffee right now? Dunkin Donuts; what is their optimization function? Are they trying to get you to be healthy in 20 years or to buy another donut now? Your cellphone; what is it trying to do? To get you to be a productive citizen in two years or to check your phone a couple of more times a day?

So what happened is we are in an environment that tempts us all the time. These temptations are only increasing. And because of that we fail. We fail; we fail often and because of that it reduces dramatically our ability to do things like save and eat well, take care of our health and therefore our total well-being is going down dramatically as well.

Directed / Produced by Jonathan Fowler, Elizabeth Rodd, and Aaron Lehmann