There and back again: Adaptation after repeated rule changes of the game

Rule changes have offered a natural experimental setting in the sports environment and beyond for many years. However, an understanding of human behavioural adaptation processes after repeated rule changes is missing from the extant literature. The NBA offers a unique setting in which the three-point line was moved (shortened) for a period of three seasons (1994-95 to 1996-97) and then returned (lengthened) to its original position (pre 1994-95). We are therefore not only able to explore the behavioural changes after reducing distance restrictions but also how players re-adapt to the original, more difficult condition. Using a dataset of almost 700,000 player-game level observations we find that (on average) players instantaneously adjust to rule changes. Good scorers and younger players take particular advantage of the situation. On the other hand, older players decrease their 3-point attempt ratio and do not readjust after a return to the original distance. Positive feedback regarding 3-point efficiency encourages players to try more shots while efficiency gains in 2-point shots reduces this incentive, indicating that players may follow the heuristic of “win-stay”. Finally, making 3-point shots easier for a couple of seasons has positive externalities on efficiency that last more than a decade after the re-adjustment of the distance.