Thinking and Deciding

194 JUDGMENT OF CORRELATION AND CONTINGENCY
the teacher expects such a correlation, she tends to perceive it in children’s behavior.
The correlations that people expect to see, however, are not always the ones that are
present.
This was demonstrated in a study done by Shweder (1977; further discussed and
reanalyzed by Shweder and D’Andrade, 1979). Shweder reanalyzed the data from
a much earlier study of introversion and extroversion in children in a summer camp
(Newcomb, 1929). The counselors at the camp provided daily ratings of the behavior
of each child, on such items as “speaks with confidence of his own abilities,” “takes
the initiative in organizing games,” and “spends more than an hour a day alone.”
Because the daily ratings were made as soon as possible after the occurrence of the
relevant behavior, the ratings were presumably as accurate as possible. From these
data, it was possible to measure the correlation of every type of behavior with every
other type of behavior over the entire summer. For example, the correlation between
“gives loud and spontaneous expressions of delight or disapproval” and “talks more
than his share of the time at the table” was .08, indicating a very weak relationship
between these two behaviors; children who tend to exhibit the first behavior are not
much more likely to exhibit the second behavior than children who do not exhibit the
first. Shweder made a list of all of these correlations, one correlation for each pair
of behaviors. (The correlations concerned children. All judgments made of a given
child were averaged before the correlations were computed.)
At the end of the summer, when the details of day-to-day happenings had been
forgotten, the counselors filled out ratings of the same children on the same items.
This situation is more like the questionnaires used in personality measurement, where
ratings are based on long-term memory rather than specific day-to-day events. Once
again, a list of correlations was made, one correlation for each pair of behaviors.
Shweder then looked at the correlation of the two lists (of correlations). If the correlation
of the two lists was high, those behavior pairs that had high correlations in
one list would have high correlations in the other, and likewise for low correlations.
For the two items described earlier, the correlation based on memory was .92 (rather
than .08); thus, in this case, a high correlation in one list went with a low correlation
in the other. Although the degree of difference observed for these two items was extreme,
the two lists of correlations were, in general, not themselves correlated. The
correlation between the daily-rating correlations and the memory-based correlations
was only about .25. 2
Why is there such a weak relationship between the correlations of daily ratings
and the correlations of the memory ratings? Perhaps because of a sort of halo effect.
People think that certain traits ought to go together, so when they give a high rating
on one, they tend to give a high rating on the other as well, and vice versa.
To get a better idea of what people think ought to go with what, in personality,
Shweder asked a number of University of Chicago undergraduates to rate all of
the pairs of behavioral descriptions from the summer-camp research for “conceptual
similarity,” thereby creating a third list. These conceptual-similarity ratings corre-
2 This was the average over several studies of this type (Shweder and D’Andrade, 1979, p. 1081).