Effect of feedback on base-rate utilization.

Investigated the effect of direct training with feedback on a base-rate problem of the engineers-lawyers type. Ss were 59 undergraduates assigned to 1 of 3 conditions: feedback, training only, and control. Ss in each condition were presented 2 base-rate problems. Results show that feedback led to adjusted probability estimates closer to the Bayesian norm than those in the no-feedback training-only condition. For a 2nd base-rate problem, no effect of training was shown, even though thinking-aloud protocols for this problem showed that Ss mentioned base-rates more often in the feedback than in the no-treatment condition