Habituation
But something strange happens when we extend this problem in time.
Researchers invited volunteers to come to the laboratory for a snack once a week for several weeks. They asked some of the volunteers (choosers) to choose all their snacks in advance, and the choosers usually opted for a healthy dose of variety. Next, the researchers asked a new group of volunteers to come to the lab once a week for several weeks. They fed some of these volunteers their favorite snack every time (no-variety group), and they fed other volunteers their favorite snack on most occasions and their second-favorite snack on others (variety group). When they measured the volunteers’ satisfaction over the course of the study, they found that volunteers in the no-variety group were more satisfied than were volunteers in the variety group. In other words, variety made people less happy, not more. How can variety be the spice of life when one sits down with a friend at a restaurant but not when one orders snacks to be consumed in successive weeks?
When we have an experience on successive occasions, we quickly begin to adapt to it, and the experience yields less pleasure each time. Psychologists call this habituation. (Economists call it declining marginal utility.) One way to beat habituation is to increase the variety of one’s experiences. Another way is to increase the amount of time that separates repetitions of the experience. Time and variety are two ways to avoid habituation, and if you have one, then you don’t need the other. In fact, when episodes are sufficiently separated in time, variety can actually be costly.