People prefer confidence to expertise when they look for advice:
In [Carnegie Mellon professor Don 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. Describing his work at an Association for Psychological Science meeting in San Francisco last month, Moore said that following the advice of the most confident person often makes sense, as there is evidence that precision and expertise do tend to go hand in hand. For example, people give a narrower range of answers when asked about subjects with which they are more familiar (Organizational Behavior and Human Decision Processes, vol 107, p 179).
There are times, however, when this link breaks down. With complex but politicised subjects such as global warming, for example, scientific experts who stress uncertainties lose out to activists or lobbyists with a more emphatic message.
So if honest advice risks being ignored, what is a responsible scientific adviser to do? “It’s an excellent question, and I’m not sure that I have a great answer,” says Moore.