ARI SHAPIRO, HOST:
The NFL season gets underway tomorrow when the Detroit Lions visit the Kansas City Chiefs. Football is a numbers game, and there's been a shift underway in the numbers on players' jerseys. NPR's Gabriel Spitzer says a new psychological study may help explain why.
GABRIEL SPITZER, BYLINE: Wide receivers used to only wear numbers in the 80s. Then, in 2004, the league changed the rules and allowed them to instead pick a number between 10 and 19. Within a few years, a ton of them had chosen the lower numbers. Kevin Seifert, a staff writer for ESPN, did a quick census and found that nearly 80% of NFL wide receivers had made the switch. He was curious about why.
KEVIN SEIFERT: In talking to some of the players who did it, many of them kept talking about how they felt like they were faster in a number that was smaller. A lot of them said they just thought they looked better or thinner.
SPITZER: Seifert wondered whether this was a real thing. Do people associate lower numbers with swifter, svelter athletes? He contacted a UCLA psychology professor named Ladan Shams.
SEIFERT: She was very clear that she didn't have any research to back it up, but that it would make a lot of sense. The way the brain works is that, over time, you might associate smaller numbers with smaller objects.
LADAN SHAMS: So that was just conjecture, a hypothesis. So because there was no prior research, we decided to test it ourselves in my lab.
SPITZER: Shams did just that. She showed people images of football players of various body types in a random jersey number and had them rate the players' slenderness versus huskiness. She says lower numbers were strongly associated with the perception that the player was thinner. Even a tiny difference mattered - 17 was seen as slimmer than 19. Of course, some numerals are wider than others. So to make sure that that wasn't affecting people's perceptions, she tested out numbers that had the same digits but reversed - say, 18 versus 81.
SHAMS: And we got the same results, and we realized that the effect is actually very robust.
SPITZER: Shams says what could be at work is a learned association between high numbers and large size. The 20-pound bag of rice is bigger than the 5-pound bag.
SHAMS: Our brains keep track of the statistics and the regularities in our environment. And then they use that information, and that forms expectations that shape our perception. And this is happening all the time, unbeknownst to us.
SPITZER: This year's NFL season has yet another twist. For the first time, players will be allowed to wear the lowest number of all - zero.
SEIFERT: If No. 10 or No. 13 makes you look thinner and faster than No. 84 or 86 or something, I wonder what the perception of zero would be.
SPITZER: The new study is set to be published in the journal PLOS One.
Gabriel Spitzer, NPR News.
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