Monkeys choose variety for variety's sake

In fact, they'll even eat a less-preferred food from that buffet when the favorite food is on it. They choose variety for variety's sake.

The choices made by these captive-bred monkeys in an Italian research facility seem to show some innate desire to seek variety, said Dan Ariely, the James B. Duke Professor of psychology and behavioral economics at Duke University.

In a series of experiments Ariely conducted with colleagues at the Instituto di Scienze e Tecnologie della Cognizione in Rome, the eight monkeys first had to be taught that the abstract tokens, such as poker chips, plastic cylinders and metal nuts, represented different kinds of choice. With training, the tokens were associated with being able to buy one piece of the most-preferred food, or being able to buy one piece from an assortment of foods that included the most-preferred food.

Lead author Elsa Addessi has used this token method before with this troop of capuchins, who are on public display as well as being used in non-invasive cognitive experiments.

"Economically, the tokens should be equivalent, because they both give you the food you like," Ariely said.

But once they had the hang of it, the monkeys as a group chose to use the variety tokens and not the "single-food-tokens." Moreover, once they chose the variety tokens the monkeys also didn't always take the most-preferred food when it was offered as part of the variety assortment. What this means is that they prefer variety for variety sake and are willing to eat food they like less to satisfy their desire for variety.

The work appears online in Behavioural Processes.

The implications of this simple experiment shed some light on consumer behavior, Ariely said. Earlier work on variety-seeking has found that people eat 43 percent more M&M candies when there are 10 colors in the bowl instead of just seven. "People choose variety for variety's sake," Ariely said. "They often choose things they don't even like as well just for the variety. We knew about this, so the interesting thing was to figure out how basic it is."

Pretty basic, apparently. The behavior of the capuchins, which are native to South America, "suggest that there's some inherent basic strategy for variety," Ariely said. In the wild, variety seeking may help ensure a nutritionally varied diet. It is also possible, the authors suggest, that variety-seeking contributed to the rise of bartering and then abstract money in human society.

At the same time, Ariely is somewhat puzzled that humans can get stuck in a rut and not seek more variety. "Ask yourself: How many new things have you tried lately? Have you tried every cereal in the cereal aisle?" It may be that you're enjoying a daily bowl of a cereal that you would rate as an 8, when just a few feet away on the shelf there is a cereal you'd rate as a 9, but you've never tried it.

Businesses can push variety on customers with assortment packs, Ariely suggests, and vicarious experiences like the Food Network can encourage exploration as well. "How do we get ourselves to explore? Even monkeys do it -- so maybe we should also try more variety."

The research was supported by the Instituto di Scienze e Tecnologie della Cognizione and Duke.