Knowledge that Transforms

In the experiments reported here, individuals with experience in a multivariate prediction setting showed considerable moderation of subsequent univariate predictions, compared to those without such experience. We show that such moderation of prediction does not result from an abstract rule of regression to the mean; rather, it can be explained by the named error model. According to this model, missing predictors are treated as an error term, with their unknown values replaced by central tendencies. Experiment 1 demonstrates the phenomenon of moderation following multivariate experience and explores its generalization to novel predictors. Moderation occurs even for a perfectly valid predictor, contrary to normative application of a regression strategy. Experiment 2 shows that the phenomenon depends on lack of correlation among the multivariate predictors. This accords with the named error model, which asserts that if missing predictors are perceived to be correlated with the available predictor, their unknown values are replaced by extreme values rather than by central tendencies. Experiment 3 shows that mere exposure to additional predictors has no effect; experience in which multiple predictors are used to make numerical predictions seems to be necessary in order to obtain subsequent moderation. In Experiment 4, feedback is introduced. Moderation of prediction results even without prior multivariate experience. However, multivariate experience produces the moderation effect much more quickly.

One hundred and twenty undergraduates (60 male and 60 female) served as leaders for a one-way communication task. They were selected for the leadership position on the basis of merit or preferential selection. Among those selected preferentially, one group was given no information, another group was given positive information, and a third group was given negative information about their task-related leadership ability. As expected, when selected preferentially and provided with no ability information, males did not differ in self-views but females were far more negative in self-views than those selected on the basis of merit. However, when provided with positive information about task-related ability women selected preferentially did not differ in self-view from those selected on the basis of merit, and when provided with negative information about task-related ability men selected preferentially did evidence more negative self-views then those selected on the basis of merit. Measures of self-view included evaluations of performance, perceptions of general leadership ability, and desire to persist in the leadership role. The findings lend support to the idea that confidence in task-related ability is an important determinant of reactions to preferential selection. Implications of these findings, both theoretical and practical, are discussed.