Yale researchers analyze 300,000 free throws, say “hot hand” effect is real

The existence of “hot” streaks among athletes–periods of consistent high performance–has been a matter of contention among scientists, some of whom have found that the idea is likely a myth. But after analyzing thousands of free throws taken by National Basketball Association players, Yale School of Medicine researchers say there’s evidence that the “hot hand” phenomenon is real.

To examine the perceived phenomenon, Gur Yaari and Shmuel Eisenmann analyzed close to 300,000 free throws taken during the 2005 through 2009 NBA seasons. They found that when a player was successful on his first free throw attempt, he had a significantly higher probability of hitting the second one as well. Their findings were published this week in the journal PLoS ONE.

Yaari and Eisenmann noted that it’s still not clear whether the “hot hand” phenomenon is the result of success breeding success, or whether players simply have better and worse periods. The authors speculated that the latter explanation is more likely.

The existence of the hot hand phenomenon has been intensively debated among researchers. Yaari and Eisenmann attributed interest in the subject to a 1985 paper published in the journal Cognitive Psychology that was aimed at studying “how human subjects misperceive random sequences and tend to attribute non-random patterns to completely random data.” Those researchers, Thomas Gilovich, Robert Vallone and Amos Tversky, argued that observed patterns could have been produced at random.

“In retrospect, it seems like a very long journey to walk through just in order to notice that human subjects have good periods and bad periods and that the time sequence results can not be produced from a binomial independent repeated trials with a constant probability of success,” Yaari and Eisenmann wrote.

Nonetheless, they said they hope their findings will lead to further study.

“We hope that this work will pave the way for studying the more important questions concerning the ‘hot hand’ phenomenon such as what are the physiological and psychological causes for the changes in the probabilities of success and how do the players and observers perceive these indicators for good and bad periods,” they wrote.