Knowing the crowd within: Metacognitive limits on combining multiple judgments.

We investigated how decision-makers use multiple opportunities to judge a quantity. Decision-makers undervalue the benefit of combining their own judgment with an advisor's, but theories disagree about whether this bias would apply to combining several of one's own judgments. Participants estimated percentage answers to general knowledge questions (e.g., What percent of the world's population uses the Internet?) on two occasions. In a final decision phase, they selected their first, second, or average estimate to report for each question. We manipulated the cues available for this final decision. Given cues to general theories (the labels first guess, second guess, average), participants mostly averaged, but no more frequently on trials where the average was most accurate. Given item-specific cues (numerical values of the options), metacognitive accuracy was at chance. Given both cues, participants mostly averaged and switched strategies based on whichever yielded the most accurate value on a given trial. These results indicate that underappreciation of averaging estimates does not stem only from social differences between the self and an advisor and that combining general and item-specific cues benefits metacognition.