There are few theories as well known in the history of psychology as that of cognitive dissonance. First pioneered by Leon Festinger and his colleagues in the 1950s, the theory says that if we engage in an activity contrary to our desires, we will rationalize our behavior by changing our evaluation of the activity to bring it in line with our actions. For instance, in the classic study, students who were paid $1 to engage in a boring task (repeatedly turning each of a set of pegs 90 degrees in sequence) rated the task as more interesting afterwards than those who were paid $20 to do the same thing. Members of the $1 group needed to explain to themselves why they had done the task, while members of the $20 group were satisfied that they had done it for the money alone. A classic counterintuitive experimental result: pay people less, they like the task more. Cognitive dissonance has been confirmed in hundreds of studies since… or has it?

Fast forward more than 30 years to 1990. The self-described world’s smartest woman, Marilyn vos Savant, claims to have discovered an odd wrinkle in the 1970s television game show “Let’s Make a Deal.” The host of the game, Monty Hall, would show three closed doors to a contestant and ask her to pick one. It was known to all who watched the show that one of the doors had a big prize behind it (such as a car) and two of the doors had booby prizes (such as a goat). Before opening the door selected by the contestant, however, Monty would open one of the other doors to reveal a booby prize. He would then give the contestant the choice of sticking with her originally-selected door, or switching to the other remaining closed door. Almost everyone had long assumed that it made no difference; that with a choice between two doors, the odds of winning the big prize were 50-50, the third, now-open door being irrelevant to the problem. Vos Savant showed that, in fact, switching to the new door increases one’s odd of winning to 2/3, while staying with the original door leaves one with only a 1/3 chance of winning. (The reason is that Monty Hall does not choose which door to open randomly. He chooses it with inside information of which door the big prize lies behind which, 2/3 of the time, will be one of the doors the contestant did not select.) A colossal public debate ensued, with even many mathematicians claiming vos Savant was wrong, but it is now clear that she was correct about what has since come to be known as the Monty Hall problem. (If you don’t believe me, you can play the game for yourself here.) Another classic counterintuitive result.

What do the two counterintuitive results have to do with one another? Yale economist M. Keith Chen has now argued that “cognitive dissonance” results are not the outcome of rationalization (or any other cognitive process) at all but, rather, are examples of the odds changing because of the initial selection of one activity over another. In short, cognitive dissonance advocates have, for over half a century, been unwitting victims of the Monty Hall problem. In some recent research aiming to show that even monkeys experience cognitive dissonance, the animals were shown three colors of M&M candies that they had apparently shown equal preference for in pre-tests. They were forced to choose only one from among two of these three colors of candy (say, red over blue). When they were then forced to choose between the unselected color (e.g., blue) and the third color (e.g., green) they chose green much more often. The psychologists doing the experiment interpreted this as evidence of cognitive dissonance in the monkeys — having rejected blue once in favor of red, they then “rationalized” their decision by rejecting it again in favor of green. But Chen argues that the result can be explained entirely in “Monty Hall” terms. As it was put in a recent New York Times article by John Tierney:

But Dr. Chen says that the monkey’s distaste for blue can be completely explained with statistics alone. He says the psychologists wrongly assumed that the monkey began by valuing all three colors equally.

Its relative preferences might have been so slight that they were indiscernible during the preliminary phase of the experiment, Dr. Chen says, but there must have been some tiny differences among its tastes for red, blue and green — some hierarchy of preferences.

If so, then the monkey’s choice of red over blue wasn’t arbitrary. Like Monty Hall’s choice of which door to open to reveal a goat, the monkey’s choice of red over blue discloses information that changes the odds. If you work out the permutations (see illustration), you find that when a monkey favors red over blue, there’s a two-thirds chance that it also started off with a preference for green over blue — which would explain why the monkeys chose green two-thirds of the time in the Yale experiment, Dr. Chen says.

Who says the history of psychology doesn’t change? 🙂

ADDITION (about 7 hours after the initial posting): Interesting as Chen’s interpretation of the monkey experiment is, I see no obvious application of Monty Hall-style analysis to the experiments that originally put cognitive dissonance on the psychological “map” — the peg-turning experiment and the study showing that people downgrade their evaluation of cars they have decided not to buy within days of having purchased another car.