Representative design: Does the addition of a defender change the execution of a basketball shot?

The aim of this study was to examine the influence of a defender on the performance of a motor skill from an invasion sport. Highly skilled basketball players performed different variations of basketball shots using a randomised test schedule. Participants completed a total of 30 test trials comprising 6 trials of 5 different shot types in both defended and undefended conditions. The presence of a defender led to significant changes in several behavioral measures including faster shot execution times, longer jump times, and an increase in the amount of time that the ball spent in the air as it travelled to the basket after being released from the shooter's hand. These behavioral changes were accompanied by an overall decline in shooting accuracy of over 20%. Defended shots also tended to elicit greater amounts of movement variability which, when interpreted in conjunction with the other findings, suggests that participants were attempting to adapt their movements to accommodate for the changing demands of the performance environment. Comparisons across different shot types revealed that the influence of the defender was generally context and task dependent. The results have important implications for representative task design, and highlight how the manipulation of key information sources can have a marked effect upon behavioral responses. •Basketball shots performed against a defender elicited significant behavioral changes.•Defended shots tended to be associated with higher levels of movement variability.•Shooters adapted their movements to accommodate for the changing task constraints.•Different shot types revealed different behavioral responses from the shooters.•Representative design is important for experiments and practice tasks.