A Simple Guide to Confirmation Bias

During today’s Simona Halep-Mirjana Lucic-Baroni match, an ESPN commentator said, “I can’t think of a male player with the yips on their serve,” implying, of course, that we were watching an all-too-typical spell of mental weakness on the part of a female tennis player.

There are a staggering number of variants along these lines, untested memes that commentators and pundits mindlessly repeat from one generation to the next. Tennis fans grow up hearing them, and once such a belief is implanted, it’s difficult to get rid of it.

There’s a technical term for this: confirmation bias. People tend to look at evidence in a way that supports their existing beliefs. Since most evidence isn’t clear cut (or it is spread out over hundreds of tennis matches), it isn’t that hard.

For example, take the belief that female players are more likely to get the yips on their serve than men are. If you’re watching any match, you’ll see one of the following four things happen:

  • A female player appears to get the yips. More evidence that women get the yips more than men!
  • A female player doesn’t get the yips. Huh, that’s strange… women usually get the yips!
  • A male player appears to get the yips. Huh, that’s strange… men usually don’t get the yips!
  • A male player doesn’t get the yips. More evidence that women get the yips more than men!

Take any bit of conventional wisdom, and as you listen to commentary during the US Open, you’ll probably hear confirmation bias in action.

There’s a simple solution here: If you don’t know something to be true, don’t repeat it as if it’s true. Our brains relentlessly look for patterns, and often they identify patterns where no pattern really exists. Or, as William Blake put it, “To generalize is to be an idiot.”

Better yet, test the generalization to see if the conventional wisdom really is true. For instance, in contrast to the conventional wisdom that women hit far more unforced errors than men do, the data says that the difference is only slight.

In a perfect world, we’d all stop spouting untested generalizations. In this world, it would be a good start to at least pull the plug on generalizations that perpetuate widely-held sexist beliefs.

11 Responses

  1. Andrew
    Andrew August 29, 2014 at 4:58 pm |

    Yeah, but the fact remains that most men hit a kick serve on their second serve, which lets them swing out and still have a large margin of error, while most women hit a slice serve on their second serve that passes much closer to the net, thereby preventing them from swinging out in the same way the men can. This isn’t to say women can’t have effective second serves, as Serena Williams demonstrates it is very possible for a woman to have a highly effective kick second serve.

    1. Jeff
      Jeff August 29, 2014 at 5:03 pm |

      That has nothing to do with commentators implying that women are mentally weaker than men.

      1. Andrew
        Andrew August 29, 2014 at 10:35 pm |

        That’s the reason women “get the yips” more on their serves.

        1. Jeff
          Jeff August 29, 2014 at 11:23 pm |

          No, it’s not. It’s a reason women double fault more, and a reason women don’t hold serve as often. Saying that someone gets the yips implies mental weakness.

  2. Cynthia Tanner
    Cynthia Tanner August 29, 2014 at 4:59 pm |

    Excellent piece – pithy and thought-provoking.
    The broadcaster phrase “uncharacteristic unforced errors” comes to mind.

    Nadal, Ferrer, and Djokovic commit “uncharacteristic unforced errors.” Murray tends to commit the normal kind.

    1. Jeff
      Jeff August 29, 2014 at 5:07 pm |

      Yep, that’s a great example. The speaker has more to do with the choice of the word “uncharacteristic” than the player does.

  3. harrison
    harrison August 29, 2014 at 6:16 pm |

    How about applying that logic to this recent changeover article about how the WTA tour is more intense than the ATP tour?


    Any reason why you didn’t criticize it?

    1. Jeff
      Jeff August 29, 2014 at 7:31 pm |

      I don’t feel the need to pass comment on everything that has ever been written about one gender or the other.

      1. harrison
        harrison August 29, 2014 at 10:10 pm |

        Oh, definitely not everything ever written. But maybe things that are written in a blog you’re a part of.

        You know what? This isn’t really directed at you. This is directed towards the Changeover members who criticize tennischannel for allowing a piece on the differences between the genders that has a lot of confirmation bias in it. When they were praising such a piece less than two weeks ago. There are of course many differences between the two articles, but the main one is that the changeover piece makes women look better, when the TC piece makes them look worse.

        Im not going to name anyone or criticize anyone directly, because that will probably not help much. Feel no need to defend the decision to include that article in the changeover, because that will mean criticizing someone you invited to write an article. But for future reference, understand this hypocrisy. You want to show the tennis community how writing is done, how they shouldn’t analyze the differences between the ATP and the WTA based off of things they don’t know, just a few generalizations, do so. But do it when it reflects positively on women, not just when it reflects negatively. That will send a message.

        1. Amy
          Amy August 29, 2014 at 11:28 pm |

          Wow, get over it. The WTA piece was praising the intensity of the rivalries at the top of the game. The Big Four are more friendly with one another, I’d like you to try to make a convincing argument otherwise.

          Additionally, when women have been systematically criticized for as long as the sport has been around because of their gender, there’s a big difference between writing something praising the WTA and writing something negative about the tour about how their hormones prevent them from handling their success well. If you can’t see the difference there, then you really shouldn’t bother reading our site.

          1. harrison
            harrison August 29, 2014 at 11:56 pm |

            The writer made points that were quite general about the WTA. She did discuss specific examples about the big stars, but they were just examples, her point was more broad. For example, how the WTA and the ATP as a whole are defined-“And, just as the Fedal niceness has come to define the current ATP, today’s WTA owes no small debt to Henin and her indomitable will to win.”
            She is speaking generally about the WTA, and I didn’t learn that just from the title of the piece:

            “Anyone who is tired of the smiles, stomach pats, and good natured ribbing of the ATP tour need only take in a few WTA matches to find the intensity they’re missing”… “So, the next time a commentator laments the congeniality of today’s tennis game, direct him or her to the nearest WTA match – chances are, it will be fierce.”

            Im not saying that the changeover piece is as bad as the tennischannel piece, but if you’re going to make a point about confirmation bias and making generalizations, try applying it on yourselves as well.

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