By Danielle Zhu

It’s a compelling idea: With a fair amount of concentration and hard work, we can become experts in any field we choose. Malcolm Gladwell popularized the theory in his 2008 book, Outliers. Based off of researcher Anders Ericsson’s study from 1993, Gladwell introduced the idea that talent coupled with at least 10,000 hours of deliberate practice is the key to mastery in cognitively demanding fields, like music and chess. In the study, Ericsson looked at violinists in a music academy and found that those who were “experts” had accumulated an average of over 10,000 hours of deliberate practice, defined as “activities that have been specially designed to improve the current level of performance.” He concluded that individual differences in performance could be attributed to the amount of deliberate practice.

However, members of the scientific community have challenged Ericsson’s conclusions and the 10,000-hour rule. A recent study in Intelligence and a meta-analysis in Psychological Science have stirred up fresh debate about the relationship between practice and performance.

In the Intelligence article, researchers looked at six studies on chess expertise and eight studies on music expertise. In their analysis, deliberate practice accounted for 34 percent of the variance in chess performance and about 30 percent of the variance in music performance—meaning a majority of the variance in performance was explained by factors other than practice. Similarly, the meta-analysis in Psychological Science examined 88 studies and found that deliberate practice explained just 12 percent of the variance in performance, with values varying across different domains (26 percent for games, 21 percent for music, 18 percent for sports, 4 percent for academic achievement, and less than 1 percent for professions in other domains).

These figures suggest that while deliberate practice influences performance, it is much less important than Ericsson and colleagues have claimed. “Practice, though without question an important predictor of differences in skill, is simply not the whole story,” says Michigan State University’s Zach Hambrick, lead researcher of the Intelligence study.

The notion that thousands of hours of practice don’t necessarily guarantee greatness may be hard to swallow for some, especially those that believe in the intrinsic value of hard work and perseverance. But according to Brooke Macnamara, the lead researcher of the Psychological Science meta-analysis: “If we have a false belief [in practice] and it’s being perpetuated, then that can cause problems in how people make decisions about how to spend their time, effort, and money. But if someone did put a lot of work in something and didn’t achieve it, at least they can say ‘Oh, that wasn’t the best fit for me, [instead of] ‘I’m a failure.’”

A variety of other factors contribute to performance. For example, studies have shown that adult chess players who started at a younger age had a higher chess rating than those who started at a later age, even when controlling for the hours of deliberate practice they had accumulated. The evidence suggests that it’s not just the amount of time one practices that makes a difference: There may actually be a “critical period” for the acquisition of skills that lead to expertise, just as there is for language acquisition.

Personality, too, may influence performance indirectly by disposing a person toward more or less deliberate practice. A study by Angela Duckworth and colleagues found that among Spelling Bee contestants, “grit”—defined as persistence in achieving long-term goals—positively predicted deliberate practice, which in turn positively predicted performance.

Hambrick speculates that different personality traits could directly influence performance, depending on the domain. For example, he believes conscientiousness may be negatively predictive in tasks like musical sight-reading or language interpretation, which require quick processing; too much vigilance or control would slow down performance.

Many researchers believe the focus on practice—as essential as it is—has overshadowed other key factors behind expertise and performance. What they are and how much they matter is not yet clear. “We may never be able to completely explain all of the remaining variance,” Hambrick says. “Human behavior is hard to predict perfectly.”

Danielle Zhu is a former PT editorial intern.

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