Bryant - Reuters *- 07122011
TOO MANY SHOTS: Bryant after L.A.’s playoff loss in January. Making three-pointers encouraged him to take more, missing many. Photo by Reuters
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Every basketball fan is familiar with the concept of having a hot hand, but new research at the Hebrew University of Jerusalem suggests that hitting three-pointers in the NBA, and then following up with more shots from behind the arc, can lead to worse results and poor choices by the shooter.

The research "raises doubts about the ability of athletes in particular, and people in general, to predict future success based on past performance," according to a statement released by the institution.

Dr. Yonatan Loewenstein and graduate student Tal Neiman at Hebrew University studied this phenomenon by examining more than 200,000 attempted shots from 291 leading NBA players during the 2007-08 and 2008-09 regular seasons, as well as over 15,000 attempted shots by 41 of the WNBA's top players from the 2008 and 2009 seasons. The results appear this week in the latest issue of the Nature Communications online journal.

"The researchers studied how scores or misses affected a player's behavior later in the game and found that after a successful three-pointer, players were significantly more likely to attempt another three-pointer," the university announced Tuesday.

The analysis also indicated that players who make shots tend to make their next attempt from the same distance. The article specifically mentions Kobe Bryant of the L.A. Lakers: The researchers found that 53 percent of the time, following a successful three-point shot, Bryant took another attempt from beyond the arc. On the other hand, he only followed up missed three-point attempts with long-distance shots 14 percent of the time. Both for Bryant and other players, they waited less time to take their next three-pointer after hitting a trifecta than after missing one.

There is no basis, however, for the widespread opinion among fans that players at this level tend to have hot streaks. The data reveals instead that players who scored a three-pointer were more likely to miss their follow-up attempt for a trifecta, while players who missed from behind the arc were more likely to hit their next three-point shot.

"The study shows that despite many years of intense training, even the best basketball players over-generalize from their most recent actions and their outcomes," said Loewenstein. "They assume that even one shot is indicative of future performance, while not taking into account that the situation in which they previously scored is likely to be different than the current one."

The researchers argue that this behavior shows how learning from reinforcement has its limits. "Learning from reinforcement may not improve performance, and may even damage it, if it is not based on an accurate model of the world," explained Loewenstein. "This affects everyone's behavior: Brokers make investments according to past market performance, and commanders make military moves based on the results of past battles. Awareness of the limitations of this kind of learning can improve [people's] decision-making processes - as well as those of basketball players."