@asuffield said:
The image is ambiguous so your brain interprets based on whatever memory is closest to hand. Most of this right/left brain stuff is pop science nonsense; except in certain brain disorders, it's largely irrelevant. The human mind is not a simple dimorphic thing: it has more than one bit of variation in it and you cannot classify minds based on some arbitrary scale between "logical" and "artistic". There may be relationships between those two things, if you could ever manage to define them, but they are not opposing influences, and they certainly don't have anything to do with the lateral halves of the brain.
Apart from the memory, I agree with you here (about memory: movement is clearly detected in V1 and V2, which are absolutely not memory related).
Since there's a big hole down the middle, and individual major functions tend to be clustered together in the same physical location, many functions (like language processing or counting) don't cross the boundary, and related functions tend to be close together, but that's about where it ends. Counting is not a "left-brain" function, it's just that when you look for where it is in a large number of people, it's on the left more often than it's on the right - a simple statistical trend, nothing more. This is probably related to the higher frequency of right-handed people, although nobody's been able to prove that yet.
Hold it right there, cowboy. For one, there is no big hole down the middle. There is a huge bundle of fiber tract, called corpus callosum holding hundreds of millions of neural connections. Plus there are quite a few brain centers that are not lateralized, such as the brain stem and the cerebellum, (hypo)thalamus, the midbrain, well, a lot of stuff.
Furthermore, there is some evidence that language processing actually does cross the gap. To begin with, visual and auditive input gets processed by both brain halves, so at least something jumps across. But higher level processing seems to involve both hemispheres (that's the technical term right there) as well. Since we have fMRI and MEG, the whole picture of lateralized processing has gotten a lot fuzzier. Of course, it seems there is some difference, but at the moment we have no clue about the nature of the division. What you might be right about, is that it is unlikely that left and right do the same functions or work together as one single unit.
PS Yes, I hold a post-doc in neuro-cognitive imaging and modelling.