Abstract
The relative rareness of left-handers (i.e. 10-13 %) in comparison to right-handers may provide them with a negatively frequency-dependent advantage in dual confrontations (Raymond, et al., 1996). Studies reporting a significant excess and superior performance of left-handers at the elite level of interactive sports such as fencing, cricket and tennis corroborate this view (Grouios, 2004). However, considering that expert performance increased during past decades (e.g. due to deliberate practice; Ericsson, et al., 1993) it is an open question whether the overrepresentation of left-handers in individual professional sports like tennis persists over time. In a longitudinal study (study 1) we analysed handedness distribution in players listed in men's ATP top 500 year-end world rankings from 1973 to 2010. Differentiation of left-hander frequencies by year revealed a linear decline in top 10 performers, whereas in top 100 players an inverse U-shaped pattern was found with percentages being around normal population values today. Moreover, by fitting the percentages of left-handed players found in ranking intervals of 50 players (i.e. 1-50, 51-100, etc.) to logarithmic functions for each year-end ranking we found that playing left-handed initially was but no longer is associated with high achievement in elite tennis. However, we also analysed handedness distribution in N = 3793 male and female left-handed amateur players registered in the German Westphalian Tennis Association for the summer season 2008 (study 2). Albeit the cross-sectional design limits conclusive interpretation, here a left-handers' performance advantage appears to still exist. Overall, our findings strengthen the hypothesis that left-handers do not benefit from an innate superiority but may have a frequency-dependent advantage whose impact on sporting achievement is likely to be reduced with players' expertise.
