Jun 25

“For the great majority of mankind are satisfied with appearances, as though they were realities, and are more often influenced by the things that ‘seem’ than by those that ‘are.'”
-16th-century Italian politician Niccolo Machiavelli

It’s something we come across regularly: presentation trumps content. Often what matters is not what we know, or what we have done, but rather how we spin it. It’s why cover letters are so important, and why the peripheral route to persuasion – one of advertising’s biggest weapons – works.

Now, Don Moore of Carnegie Mellon University demonstrated yet another way that we are heavily influenced by delivery — 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.

In his experiment, Don had volunteers guess the weight of people in photographs, and paid them for their correct answers. But before each guess, the volunteers were asked to choose one of four advice-givers (also volunteers) from whom to buy advice. Each advice-giver submitted their weight guess in percentage form, with some advisers spreading out their advice over multiple weight ranges. So, one advisor might have said that there was a 70% chance that the person’s weight was 170-179 pounds, a 15% chance that it was 160-169, and a 15% chance that it was 180-189. A more confident advisor, however, would have put all his eggs in one basket and said there was a 100% chance that the weight was within the 170-179 range.

Now here’s the really important part: in each round, before they chose their adviser, volunteers got to see each adviser’s percentage spread, but not the associated weight ranges. (See this really handy chart for more on the set-up.)

What did Moore find? Volunteers were more likely to buy advice from confident advisers (such as the 100% adviser from above) 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.

These findings are troublesome. Because though confidence and accuracy sometimes go hand-in-hand, they don’t necessarily do so. And when we want confident advisors, some will exaggerate to give us what we want.  Maybe this is why so many pundits on TV for example exaggerate their certainty?