Scientists Explain A Common Fight In Basketball

Enlarge this image toggle caption Beck Diefenbach/AFP/Getty Images Beck Diefenbach/AFP/Getty Images

It happens all the time during basketball games. Two players are going for the ball. They touch it at the same time but neither controls it, and it flies out of bounds.

At that point, tempers rise — both are certain that the other player was the last to touch it, which should earn their own team a chance to control the ball.

Are the players just pretending to be so sure it's out on their opponent? Or could there actually be a difference in how they experience the event that has them pointing a finger at the other player?

Those are the questions that scientists from Arizona State University tackled in a paper published in Science Advances.

"It's very possible that people experience two different orders of events, two different experiences of reality, even though they experienced the same event," Ty Tang, a cognitive science doctorate student at ASU, tells NPR.

In the experiments, the researchers found that people tend to think that their own actions happened before near-simultaneous actions close by. They found that on average, people perceive their own actions as happening about 50 milliseconds before the other motion. That's why the basketball players would be so convinced they tapped the ball before their opponent.

Tang says that generally, there's a lot of evidence that "sometimes the things that some people experience are different than others."

toggle caption Ty Y. Tang

To test this, Tang ran three different experiments with ASU students. In the first experiment, two students sat across from each other. A divider between them had slots for their hands. When a simultaneous light flashed, they each tapped a sensor on the other person's right hand, then indicated which of them they think tapped first.

"We did find a very strong effect for participants to think that their touch happened before the other person's touch," Tang says.

This wasn't a race — people were not told to try to beat the other person. Still, in more than two-thirds of the cases, the study subjects each said they were the first ones to tap.

toggle caption Ty Y. Tang

Tang got similar results when he replaced the second human with a mechanical switch. In a third experiment, he used a clicking sound instead of a switch. "Even when we removed that touch and just replaced it with a click, they still thought their touch happened before that sound," he says.

It's not clear why many people have this bias. Tang says it might support the theory that we're "constantly predicting the world and trying to create this mental model of what's going to happen." But they don't know whether there is actually a sensory difference in when things register in the brain, he says.

And it's worth noting that people don't always think their action happened first when two things happen nearly simultaneously — it's simply a significant bias. Some people are more susceptible to it than others. And, he said, other factors are likely to play into it. For example, "if it's a competitive situation, you're probably more likely to bias whatever decision is going to be more favorable to you."

Which brings us back to elite athletes. Are they more or less likely to have this bias toward their own actions?

"It's a little difficult to say and it can go either way," Tang says. Athletes deal with these quick reaction times all the time, so he is wondering whether this is a bias that can be trained away. "If you have all of these close temporal events that they have to discriminate between, then they might be better at telling which one actually happened first or second," he says.

But on the other hand, athletes are constantly in competitive situations — which, as he has noted, may exacerbate the bias.

Ultimately, though, "we really just want people to be more understanding of other people's perspectives," Tang says.

He adds: "Sometimes people actually do have different experiences of what happened and they're not lying — they might have actually just experienced it that way."