Jonah Lehrer looks at when reinforcement fails:
To answer these questions, Tal Neiman and Yonatan Loewenstein at the Hebrew University of Jerusalem turned to professional basketball. More specifically, they looked at 200,000 three-point shots taken by 291 leading players in the NBA between 2007 and 2009. (They also looked at 15,000 attempted shots by 41 leading players in the WNBA during the 2008 and 2009 regular seasons.) The scientists were particularly interested in how makes and misses influenced subsequent behavior. After all, by the time players arrives in the NBA, they’ve executed hundreds of thousands of shots and played in countless games. Perhaps all that experience reduces the impact of reinforcement, making athletes less vulnerable to the unpredictable bounces of the ball. A make doesn’t make them too excited and a miss isn’t too discouraging.
But that’s not what the scientists found. Instead, they discovered that professional athletes were exquisitely sensitive to reinforcement, so that a successful three-pointer made players far significantly more likely to attempt another distant shot. In fact, after a player made three three-point shots in a row – they were now “in the zone” – they were nearly 20 percent more likely to take another three point shot. Their past success – the positive reinforcement of the made basket – altered the way they played the game.
In many situations, such reinforcement learning is an essential strategy, allowing people to optimize behavior to fit a constantly changing situation. However, the Israeli scientists discovered that it was a terrible approach in basketball, as learning and performance are “anticorrelated.” In other words, players who have just made a three-point shot are much more likely to take another one, but much less likely to make it:
What is the effect of the change in behaviour on players’ performance? Intuitively, increasing the frequency of attempting a 3pt after made 3pts and decreasing it after missed 3pts makes sense if a made/missed 3pts predicted a higher/lower 3pt percentage on the next 3pt attempt. Surprizingly, our data show that the opposite is true. The 3pt percentage immediately after a made 3pt was 6% lower than after a missed 3pt. Moreover, the difference between 3pt percentages following a streak of made 3pts and a streak of missed 3pts increased with the length of the streak. These results indicate that the outcomes of consecutive 3pts are anticorrelated.
This anticorrelation works in both directions. as players who missed a previous three-pointer were more likely to score on their next attempt. A brick was a blessing in disguise.