Tuesday, November 13, 2007

Rationalizing our choices - an early evolutionary origin

When we humans make a choice, we protect our self esteem by rationalizing that it was the correct one, even in the face of evidence to the contrary. It turns out Capuchin monkeys do the same thing. In a kind of "why didn't someone think of trying this before?" experiment, a group of Yale psychologists offered the monkeys several different colors of M&M candies. Once a monkey was observed to show an equal preference for three colors of M&M’s — say, red, blue and green — he was given a choice between two of them. If he chose red over blue, his preference changed and he downgraded blue. When he was subsequently given a choice between blue and green, it was no longer an even contest — he was now much more likely to reject the blue. Thus the monkeys are dealing with cognitive dissonance ('should I choose the blue or the green?') by downgrading or eliminating one of the options. They performed a similar experiment with little children, obtaining similar results. The fact that children and primates show the same behavior as adults suggests that this rationalization behavior is largely unconscious, and may have appeared in evolution earlier than previously thought.


  1. Is it possible that the monkeys simply 'developed the habit of' rejecting blue discs?

    Before I would jump to any further conclusions with this experiment, as reported, I would next give the monkeys a choice between green and red M&Ms and see what happens.

    I would also, after they had accepted the red ones, given some monkeys a choice between red and green ones, followed by a choice between the one they reject and a blue one (which they rejected the first time).

  2. Anonymous12:28 PM

    I'm pretty sure they explore every contingency when they do these experiments before releasing their data. Is it so hard to believe that humans and monkeys could have something fundamental in common?