"...mistakes are critical to good decision-making, as they are our best tutors. Lehrer describes a famous study from Stanford psych research Carol Dweck, who administered easy tests to 10-year-olds, who did well on it. The control group was praised for 'being smart.' The experimental group was praised for 'trying hard.'
With only this difference, the two groups were then administered progressively harder tests. Dweck discovered that the 'smart' kids did worse: they believed their initial good result was due to some innate virtue beyond their ken or control, and feared that a failure would show that they lacked this intangible. But the 'hard-trying' group had been rewarded for taking intellectual risks, and so they continued.
Afterwards, the 'smart' kids rated the hardest tests as their least favorite; the 'tryers' rated it as their most favorite."