"In Moore's experiment, volunteers were given cash for correctly guessing the weight of people from their photographs. In each of the eight rounds of the study, the guessers bought advice from one of four other volunteers. The guessers could see in advance how confident each of these advisers was (see table), but not which weights they had opted for.
From the start, the more confident advisers found more buyers for their advice, and this caused the advisers to give answers that were more and more precise as the game progressed. This escalation in precision disappeared when guessers simply had to choose whether or not to buy the advice of a single adviser. In the later rounds, guessers tended to avoid advisers who had been wrong previously, but this effect was more than outweighed by the bias towards confidence.
The findings add weight to the idea that if offering expert opinion is your stock-in-trade, it pays to appear confident."
"Don Moore of Carnegie Mellon University demonstrated… [that we] tend to seek advice from experts who exhibit the most confidence – even when we know they haven’t been particularly accurate in the past…. Volunteers were more likely to buy advice from confident advisers… than those who spread out their percentages. What’s more, this tendency led advisors to make their advice more and more precise in subsequent rounds – but not more accurate."