The 'learned parameters' hypothesis as an explanation of the especial skill effect

It has been debated that we have a single memory representation for a class of motor skills as opposed to a single representation for each single movement within a class (see Schmidt & Lee, 2005). In recent years renewed interest in this topic has emerged, challenging the concept across all motor skills that a single generalized memory structure represents all actions within a class. In studying the performance of expert basketball players executing the set shot from the foul line (i.e., 15 ft from the basket), this well-practised shot was found to be more accurate than at closer distances and hence from the performance scores predicted based on a generalized motor program view of behaviour. We tested the ‘learned parameters’ hypothesis as an explanation of the especial skill effect (Keetch, Schmidt, Lee, and Young, 2005). Outcome attainment and movement kinematics were recorded for 10 expert and 10 novice players performing basketball free-throw shots at five distances (11ft, 13ft, 15ft, 17ft and 19ft) with a regular and heavy weight basketball. Separate regression equations were calculated to estimate the expected performance at the free throw line (15ft). As predicted, experts performed better than expected relative to the regression equation at the 15 ft, free-throw line with the regular basketball, supporting the especial skill effect. This effect was not present for the experts when shooting with the heavy ball. Novices did not show an advantage at the free-throw line when performing with either ball. Although the outcome attainment scores support the ‘learned parameters’ hypotheses, kinematic analysis failed to identify differences in the movement pattern for the especial skill, suggesting that these skills (i.e., shooting at different distances) are not governed by separate motor programs.