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posted by Fnord666 on Saturday April 11 2020, @09:26PM   Printer-friendly
from the too-many-balls-in-the-air dept.

Scientists ponder how jugglers seem to defy limits to human reaction times:

The fastest expert jugglers can make nearly 500 catches per minute, which translates into just 120 milliseconds per catch—faster than human reaction times even in high-speed sports like tennis, in which a player typically takes 200 milliseconds to adjust their performance. The Guinness world record for juggling is currently 11 balls. Troy Shinbrot, a biomedical engineer at Rutgers University, and Rutgers undergraduate math major Jonah Botvinick-Greenhouse explored the question of how expert jugglers can achieve these remarkable feats in a recent article in Physics Today.

Master jugglers are clearly very good at multitasking, and since balls aren't being thrown randomly, each ball need not be tracked and caught independently. But Botvinick-Greenhouse and Shinbrot still wondered how it was possible for jugglers with reaction times of 200 milliseconds to routinely catch balls every 120 milliseconds. "Jugglers rely on making accurate throws and predictions of where the balls will travel," the authors wrote. "The accuracy required is a measure of how unstable—and thus how difficult—a particular juggling pattern is."

Juggling has a long and glorious history dating back to ancient Egypt; there are hieroglyphics circa 1994 and 1781 BCE that historians consider to be the earliest historical record of juggling. There were juggling warriors in China (770-476 BCE)—apparently it was viewed as an effective diversionary tactic—and the practice eventually spread to ancient Greece and Rome. By the mid-1800s CE, juggling was largely practiced by circus and street performers, and it has fascinated scientists since at least 1903. That's when Edgar James Swift published a paper looking at the psychology and physiology of learning in the American Journal of Psychology, which discussed the rate at which students learned to toss two balls in one hand.

As Peter Beek and Arthur Lewbel wrote in a 1995 article in Scientific American:

[Juggling] is complex enough to have interesting properties and simple enough to allow the modeling of these properties. Thus, it provides a context in which to examine other, more complex fields... One is the study of human movement and the coordination of the limbs. Another is robotics and the construction of juggling machines. The third is mathematics: juggling patterns have surprising numerical properties.

Journal Reference:
Jonah Botvinick-Greenhouse, Troy Shinbrot. Juggling dynamics Physics Today 73, 2, 62 (2020); https://doi.org/10.1063/PT.3.4417


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  • (Score: 2, Touché) by Anonymous Coward on Saturday April 11 2020, @10:37PM (3 children)

    by Anonymous Coward on Saturday April 11 2020, @10:37PM (#981328)

    I ponder how these "scientists" seem to defy limits to human stupidity. The jugglers achieve these feats by practicing a lot before the scientist observe them., so they don't have to anticipate where the balls will be because they've already trained the balls exactly where to go.

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  • (Score: 0) by Anonymous Coward on Saturday April 11 2020, @10:45PM (2 children)

    by Anonymous Coward on Saturday April 11 2020, @10:45PM (#981331)

    Same thing with baseball. How do you think they can hit a ball coming at you at 90+ mph? Practice and anticipate.

    Some "scientists."

    • (Score: 2, Funny) by Anonymous Coward on Saturday April 11 2020, @10:51PM

      by Anonymous Coward on Saturday April 11 2020, @10:51PM (#981333)

      》How do you think they can hit a ball coming at you at 90+ mph?

      Self defense?

    • (Score: 2) by Immerman on Sunday April 12 2020, @03:26AM

      by Immerman (3985) on Sunday April 12 2020, @03:26AM (#981407)

      The batter has both more and less of a challenge.

      More, because the intercepting the pitcher's throw is far more unpredictable than intercepting your own.

      And less, because they have a good half-second to focus entirely on the oncoming ball (60.5 feet from mound to plate, divided by 90mph = 0.46seconds. That gives them a full 0.3 seconds to assess the ball's trajectory before they have to decide what their hands are going to do. And a whole lot of bat control is in the shoulders and biceps, which have a substantially shorter signal path, and can thus react much faster and give more last-moment fine-tuning to the swing.

      Really, it's kind of astounding that we're able to adapt so well so seamlessly to every muscle in our body having a different amount of signal lag to deal with. Makes those awkward teen years a bit more understandable too - not only our your strength, size, and proportions all changing in rapid and uneven ways - but those "invisible" signal lags are increasing in the same uneven ways. I understand that the adaptation is so pervasive that in tests where actions are controlled directly by brain sensors, avoiding the transmission lag, people actually perceive the actions as happening before they decide to do them.