Here's an excerpt from the article:
'it appears that praising children for their intelligence can make them less likely to persist in the face of challenges, a crucial element of grit. For much of the last decade, [some people with a lot of time on their hands] have tracked hundreds of fifth-graders in 12 different New York City schools. The children were randomly assigned to two groups, both of which took an age-appropriate version of the IQ test. After taking the test, one group was praised for their intelligence - “You must be smart at this,” the researcher said - while the other group was praised for their effort and told they “must have worked really hard.”
[They] then gave the same fifth-graders another test. This test was designed to be extremely difficult - it was an intelligence test for eighth-graders - but [they] wanted to see how they would respond to the challenge. The students who were initially praised for their effort worked hard at figuring out the puzzles. Kids praised for their smarts, on the other hand, quickly became discouraged.
The final round of intelligence tests was the same difficulty level as the initial test. The students who had been praised for their effort raised their score, on average, by 30 percent. This result was even more impressive when compared to the students who had been praised for their intelligence: their scores on the final test dropped by nearly 20 percent. A big part of success . . .stems from our beliefs about what leads to success.'