order the other way around. Scientists use something called a
correlation to measure how closely one factor predicts another,
and overall, the students’ ratings correlated with the experts’
ratings by .55, which is quite a high correlation. What this says,
in other words, is that our jam reactions are quite good: even
those of us who aren’t jam experts know good jam when we
taste it.
But what would happen if I were to give you a questionnaire
and ask you to enumerate your reasons for preferring one jam
to another? Disaster. Wilson and Schooler had another group of
students provide a written explanation for their rankings, and
they put Knott’s Berry Farm — the best jam of all, according to
the experts — second to last, and Sorrell Ridge, the experts’
worst jam, third. The overall correlation was now down to .11,
which for all intents and purposes means that the students’
evaluations had almost nothing at all to do with the experts’
evaluations. This is reminiscent of Schooler’s experiments that I
described in the Van Riper story, in which introspection
destroyed people’s ability to solve insight problems. By making
people think about jam, Wilson and Schooler turned them into
jam idiots.
In the earlier discussion, however, I was referring to things