Originally Posted by
Rob Thomson
I think the other reasons you stated are far better than this one, primarily because sound travels much more slowly than light. So, if my visual perception from the mirror is too slow to be relevant, a coach's oral cue is even slower and therefore less relevant.
I'm not arguing that mirrors > coaches, just that the quoted logic is fallacious. There are plenty of reasons coaches are awesome and mirrors suck, but speed of perception is not one of them.
For example, if my coach is standing 3 feet away, and there is a mirror 3 feet in front of me, it will take 6 nanoseconds for me to perceive my reflection, not accounting for the time it takes my brain to process the information. It will take my coach 3 nanoseconds to perceive my fault, a second or two to verbally cue me, and 3 million nanoseconds (3 milliseconds) for his cue to reach my ears. Give or take.