
Juggling Dynamics - sohkamyung
https://physicstoday.scitation.org/doi/10.1063/PT.3.4417
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nealabq
In high school I was part of a 4-man juggling troupe. Mostly club passing. I
always had to be able to see each throw at the top of its arc, but only out of
the very corner of my eye. I didn't have to focus my eyes or pay attention,
but the club or ball had to pass by some part of my visual field. I couldn't
juggle blind, not even three balls. I'd even miss just one ball about a
quarter of the time if I closed by eyes and threw it in a 18-inch arc.

So muscle memory also involves your eyes.

~~~
c22
I can juggle three balls with my eyes closed all day. I did have to work at it
though. The epiphany came when I realized that my throws were much more
critical than my catches. For several months I practiced keeping my catching
hand completely stationary and landing my throws directly into it. This way I
trained the muscle memory of the throwing hand to deliver an almost perfectly
repeatable result. It's interesting that I can't reliably do 4 balls with my
eyes closed because that's a different throw that I haven't specifically
worked on. I can do 5 balls with my eyes closed about as well* as with them
open (same throw as 3, but faster)

Obviously sight plays a more critical role when passing, but I still posit
it's the throw that counts. There was one clown I used to pass with who
delivered perfect passes like every single time and I could always get away
with crazier stuff while passing with him than I could do with other people.

* Not that well

