In a nutshell, their impressive body of research shows that  working memory—the ability to simultaneously hold information in memory while processing other information—is correlated with performance on different “complex tasks” in the laboratory, including remembering baseball information, Texas Hold’em poker performance (their manuscript on this topic is submitted for publication), memory for the movement of spaceships and baseball players, and piano sight-reading performance. What’s more, working memory performance is still correlated with these “complex tasks” even among individuals with high levels of specific experience and knowledge for the domain. Hambrick and Meinz conclude “although deliberate practice may well be necessary to reach a very high level of skill, it is not always sufficient.”

I thought about this statement, and how the media interpreted it. Something just didn’t feel right. It seemed like they were setting up a  straw man. Who really thinks that deliberate practice is completely sufficient for greatness? As if it’s even a possibility that we’re just machines, and the only thing we do is input knowledge and export greatness. Surely Hambrick and Meinz meant that deliberate practice might not be sufficient without accompanying high ability, not that deliberate practice might not be the only factor contributing to greatness. Even Anders Ericsson and his colleagues—who study the importance of deliberate practice for attaining elite performance— would have to admit that  other factors come into play, such as inspiration, motivation, passion, perseverance,  mindset, and self-belief.  Environmental circumstances also of course play a huge role, as does just plain luck (i.e., being in the right or wrong place at the right or wrong time).

So I decided to flip the question on its head. The most interesting question isn’t whether deliberate practice is both necessary and sufficient for elite performance, but whether high ability is necessary for greatness. My reading of the literature is that Ericsson’s specific argument is that (with the exception of innate constraints on body size and height) genetic endowment doesn’t put limits on the ultimate level of elite performance healthy individuals are capable of attaining. This is a different question than asking whether differences in ability contribute to differences in elite performance. Genes contribute to all of our traits (including our tendency for perseverance), and all of our traits contribute to our greatness. But this doesn’t mean that our genes necessarily constrain our potential for greatness.

The correlations found by Hambrick and Meinz, which were far from perfect, suggest that ability contributes to greatness, not constrains it. Take their study on piano sight-reading skill. They found that deliberate practice was correlated .67 (p < .01) with sight-reading performance, while working memory was only correlated with sight-reading skill .28 (p < .05). After looking at both variables simultaneously (in a  regression model), they found that deliberate practice accounted for about half of the differences (45.1%) in sight-reading performance whereas working memory accounted for an additional 7.4% of the differences in sight-reading performance above and beyond deliberate practice.

A few things to note:

- The researchers call this 7.4% increase in prediction “significant”. While they are referring to significance in the statistical sense, keep in mind that we’re talking about explaining differences. The correlation between working memory and sight-reading was .28, so 7.8% of the differences in sight-reading were explained by working memory. This means that 92.2% of the differences in sight-reading skill were not explained by differences in working memory performance. I’d say 92.2% is much more “significant” than 7.8%, at least in terms of practical meaning!

- Deliberate practice explained a much larger (45.1% vs. 7.4%) amount of the differences in sight-reading performance compared to working memory when both variables were looked at simultaneously. The facts are quite different than the media would have us believe. Look at this headline, from Psych Central: “Key to Greatness is Working Memory, Not Practice”. First of all, their studies actually show that both working memory and practice contribute to differences in performance, not one or the other. Second of all, we already determined that their studies don’t actually involve greatness. Third of all, practice is actually a much better predictor of “complex task” performance than working memory. That headline is wrong on so many levels, I could hurl!

So again I ask: is high working memory necessary for greatness?

To explore this question, I decided to look at a dataset I already had sitting on my computer. A few years back I went to Cambridge, England and administered psychological tests on high school (“ Sixth Form”) students as part of a larger study I was conducting. I had measured working memory using the Operation Span Task), which asks participants to remember words while simultaneously verifying whether easy mathematical equations are correct (e.g., “Is 2 + 4 =6?”). Working memory can become more burdened by increasing the number of words to remember. The minimum number of words I had participants remember was 2, and the maximum was 6. It’s actually pretty darn difficult to keep that many words in your head while you’re also processing math equations!