A study of violinists found that merely good players practised as much as, if not more than, better players, leaving other factors such as quality of tuition, learning skills and perhaps natural talent to account for the difference.

The work is the latest blow to the 10,000-hour rule, the idea promoted in Malcolm Gladwell's 2008 book, Outliers, which has been taken to mean that enough practice will make an expert of anyone. In the book, Gladwell states that "ten thousand hours is the magic number of greatness".

"The idea has become really entrenched in our culture, but it's an oversimplification," said Brooke Macnamara, a psychologist at Case Western Reserve University in Cleveland, Ohio. "When it comes to human skill, a complex combination of environmental factors, genetic factors and their interactions explains the performance differences across people."

The seed for the 10,000-hour rule was a 1993 study of violinists and pianists which found that accumulated practice time rose with musical prowess. On average, top-ranked violinists had clocked up 10,000 hours of practice by the age of 20, though many had actually put in fewer hours. In the study, the authors rejected an important role for natural talent and argued that differences in ability, even among top musicians, were largely down to how much they practised. Gladwell seized on the round number to explain the success of notables from Bill Gates to the Beatles.

While the less skilful violinists clocked up an average of about 6,000 hours of practice by the age of 20, there was little to separate the good from the best musicians, with each logging an average of about 11,000 hours. In all, the number of hours spent practising accounted for about a quarter of the skills difference across the three groups, according to the study published in Royal Society Open Science.

Macnamara believes practice is less of a driver. "Once you get to the highly skilled groups, practice stops accounting for the difference. Everyone has practised a lot and other factors are at play in determining who goes on to that super-elite level," she said.

"The factors depend on the skill being learned: in chess it could be intelligence or working memory, in sport it may be how efficiently a person uses oxygen. To complicate matters further, one factor can drive another. A child who enjoys playing the violin, for example, may be happy to practise and be focused on the task because they do not see it as a chore."

The authors of the 1993 study are unimpressed, however. One co-author, Anders Ericsson, a psychologist at Florida State University, said the new paper actually replicated most of their findings. He said there were no objective differences between Macnamara's best and good violinists, so no surprise they put in the same amount of practice.

Another co-author on the 1993 study, Ralf Krampe, a psychologist at the Catholic University of Leuven, said nothing in Macnamara's paper made him question the original findings. "Do I believe that practice is everything and that the number of hours alone determine the level reached? No, I don't," he said, adding that the quality of practice, teachers and parental support all matter too. "But I still consider deliberate practice to be by far the most important factor."

Macnamara said it was important for people to understand the limits of practice, though. "Practice makes you better than you were yesterday, most of the time," she said. "But it might not make you better than your neighbour. Or the other kid in your violin class."