Individual differences in expertise development over decades in a complex intellectual domain.

Learners acquire expertise at different rates and reach different peak performance levels. Key questions arise regarding what patterns of individual differences in expertise development occur and whether innate talent affects such development. International chess is a good test domain for both issues, because it has objective performance measures, actual practice measures (number of games), longitudinal population data, and minimal gatekeeper influence. Players' expertise development typically follows either a logarithmic or a power-function curve, approaching asymptote by around 750 games. A comparison of eventual top players and other eventually well-practiced players typically reveals a performance difference at domain entry, which widens progressively with practice and then stays large and constant. The data show various correlated signs of apparent greater natural talent in eventual top players: precocity (indexed by entering the domain and gaining the grandmaster title much younger on average), faster acquisition of expertise (indexed by fewer years and games needed to gain the grandmaster title from domain entry), and a higher peak performance level after extensive actual practice. A factor analysis found evidence for an underlying natural talent factor that constrains ultimate performance level.