Teaching pigeons to commit base-rate neglect.

Whereas humans display base-rate neglect in a behavioral analogue of the base-rate problem, pigeons have been shown to behave optimally in a comparable task, appropriately weighting base-rate and case-cue information. Previous studies have shown that prior experience may interfere with optimal decisions for human subjects, a result consistent with the position that poor and illogical decisions often follow from the misapplication of learned rules. The present study shows that pigeons will also display base-rate neglect if given extensive pretraining with informative case cues. Two experiments with pigeons, in a matching-to-sample procedure designed to mimic the classic base-rate problem, show that pigeons display base-rate neglect after extensive pretraining with the matching task.