Reducing bias in frequency judgment by improving source monitoring.

A common finding in judgment and decision making is that people's frequency judgments often fail to map onto objective frequencies. The present research examined the possibility that one source of bias in frequency judgment is attributable to people's inability to screen out irrelevant memory traces. We used a two-list source-monitoring paradigm to investigate whether frequency judgments are influenced by "extra-experimental" experiences and whether enhancing source monitoring improves judgment accuracy. Across four experiments we found: (1) frequency judgments regarding one list were biased by the second, (2) manipulating encoding between lists improved source monitoring and resulted in more accurate judgments, (3) manipulating item context between lists improved source monitoring and resulted in more accurate judgments, but only when the context was item specific, and (4) manipulating simple-background context between lists was ineffective at improving source monitoring.