The Wikipedia article refers to 13 cues total. Only 2 of which are under our physical control - convergence (our eyes crossing to focus) and accomodation (chang

The Wikipedia article refers to 13 cues total. Only 2 of which are under our physical control - convergence (our eyes crossing to focus) and accomodation (changing the lens shape). Providing separate images to each eye, triggers the 3d processing mechanism in a way that TV doesnt. For lifetimes, we expect if objects approach or recede, we adjust our focus, ie converge and accomodate (there's obviously a very high evolutionary advantage to getting the distances right). From what some describe, we keep attempting to focus when watching 3D and failing. Also, they're both feedback loops, there's some convergence/lens bending, the image gets a bit clearer, we keep going in the same direction, I'd guess that the brain keeps trying, fails and then reverts to focus on the 2d planes presented, 1000s of times throughout the movie, this is what causes the brain and eyeache. Possibly we can adapt, and naturally switch in and out of movie mode without discomfort, but we'd need to have movies worth seeing.