[kenbellows]

I don't agree with that description of what the brain does when you catch a ball, or with the principle it's proposing. I don't think the brain does any kind of calculations to figure out how to catch the ball; I think it's effectively muscle memory. If you've never caught anything before, your brain will have no clue what to do. As you practice running to catch things, I think a better description of your subconscious process is something like: "The ball (or whatever) looks like it's growing bigger in my visual field at a certain rate. A previous time when it grew bigger at a rate kind of like that, I applied about x force in the legs, and I didn't get there in time. Another time when it was growing at about this rate, I put applied a larger amount of force y, and the ball landed behind me. This time I'll try to apply a little more than x force, but less than y force, and see how that works."

This is a substantial oversimplification of course (there are many more factors involved than how fast the ball is growing in the visual field), but I think the point is clear enough. I doubt there's any trigonometry happening in the brain's circuitry; it seems much more plausible to me that the brain is really good at remembering how it felt in previous circumstances, recognizing how those remembered circumstances relate to the current one, and trying to adjust.

As I understand it, this is actually a significant debate in cognitive science, philosophy of mind, and related fields. One prominent proponent of a view like the one I've expressed here, that the brain doesn't require or use heavy math to do things like catch flying objects but rather acquires the ability over time through experience, is John Searle. He is known for using the example of his dog's ability to catch a ball that's bounced off a wall when discussing and arguing against theories of mind that propose that all unconscious processes must be following algorithms or rules (like running through computations to figure out how to catch a ball). Here's a quote of his from the BBC program Horizons (quote found in "New Technologies in Language Learning and Teaching", issue 532, on page 37 [1]):

  If my dog can catch a ball that's bounced off the wall, that may be
  just a skill he's acquired. The alternative view (the pro-AI view)
  would say: "Look, if the dog can catch the ball it can only be 
  because he knows the rule: go to the point where the angle of
  incidence equals equals the angle of reflection in a plane where the
  flatness of the trajectory is a function of the impact velocity
  divided by the coefficient of friction" - or something like that.
  Now, it seems to me unreasonable to think that my dog really *knows*
  that. It seems to me more reasonable to suppose he just learns how
  to look for where the ball is going and jumps *there*. And a lot of
  our behavior is like that as well. We've acquired a lot of skills,
  but we don't have to suppose that, in order to acquire these skills,
  the skills have got to be based on our mastery of some complex
  intellectual structure. For an awful lot of things, we just *do* it.

[1] https://books.google.com/books?id=fWQhj0HVCbUC&pg=PA37&lpg=P...

[klik99]

Sure, it might not be trig, but in your description there is still calculation (the ball is growing larger at x rate, so adjust my legs accordingly), just not of the self-aware conscious variety. There are really two definitions of 'calculation' that are used interchangabley - one is a) the act of deconstructing into symbols and picking apart, and the other is b) the execution of algorithm.

My point is that 'feeling' or 'muscle memory' is the execution of (super hacky, ad hoc and efficient) algorithm, the big difference between computer calculation and brain calculation being that the brain is far more plastic than the computer. Presumably in an insects mind the 'muscle memory' is hardcoded (deliberately reductionist here), whereas we have a conscious mind that can train and 'program' our unconscious mind.

In your quote, 'we just do it' is ignoring the great complexity of the human mind that can perform complex interconnected tasks with seemingly no effort at all, if it has been trained properly. Replace training with programming, and the parallels are there - graphics programming for instance is a huge collection of hacks and rules of thumb to get something that looks like perspective and light. Like our brain, it's results orientated so it truly doesn't matter if it's not 'correct'.

Now of course the brain and computers are different, but it's incorrect to say the brain doesn't calculate - it just is a lot more unwieldy to program than a computer.

[pitaj]

Please don't use code blocks for quotes. On mobile, each line wraps into two, and there's half a screen worth of empty space at the end of each line.