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Comment by MaximumYComb | Hacker News Reader

I was thinking about the manipulation issue tonight. I'd been throwing a tennis ball in the pool with my kids and I realised how instinctual my ability to catch was. A ball leaves my kids hands and I move my hand to a position, fingers just wide enough for a ball, and catch it. All of it happens in a fraction of a second.

The human brain can model the physics of a ball in flight, accurately, and quickly. As the ball touches the finger tips it makes the smallest adjustments, again in tiny fractions of a second

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I don't know if I'd call it modelling the physics of a ball in flight exactly. It kind of seems like the brain has evolved a pathway to be able to predict how ballistic projectiles - affected only by gravity and momentum - move, that it automatically applies to things.

What make me think of it like that is hearing about how the brain was actually really bad at predicting the path of things that don't act like that. This was in context of aiming unguided rocket launchers (I end up reading a lot of odd things). It seems the brain is really bad at predicting how a continuously accelerating projectile will travel, and you have to train yourself to ignore your intuitions and use the sighting system that compensates for how it actually travels in order to hit a target with the thing.

You mean the brain has evolved over millennia to model the psychics of the world and specialize in catching and throwing things

Absolutely. It also requires more than the evolutionary adaptations to do it. The skill requires the catching individual to have practiced the specific motions enough times previously to become proficient to the point it becomes second nature.

Compare what happens during a practice game of catch between six year old, first time Little Leaguers vs. MLB starters.

Dogs can do this too. And quite a bit more impressive than most humans.

It’s always impressive to watch how good my dog is at anticipating the position of the ball way ahead of time.

If I decide to kick it, he reads my body language scarily well to figure out what direction it will probably go, and will adjust his position way ahead of time. If I throw it at a wall he will run to where the angle will put the ball after it bounces. If I throw it high in the air he knows where to run almost immediately (again using my body language to know where I might be trying to throw it.). He’s very hard to fool, too, and will learn quickly to not commit to a particular direction too quickly if it looks like I’m faking a throw.

I always feel like he’d make a great soccer goalie if he had a human body.

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