Vision Splitting

While our experience of visual reality may feel seamless, a recently published study suggests that our brains actually shift visual processing tasks between hemispheres, switching cognitive hubs without us realizing it.

While some common understandings about our left and right brain hemispheres are actually misunderstandings (the supposedly hemispheric distinction between creative and analytic functions, for instance, isn’t backed by modern findings), it is true that the right side of the brain tends to manage visual spacial perception on the left side of our visual field, and vice-versa.

This division is thought to be an evolutionary optimization: it takes a lot of processing power to collect visual information and process it in real time, and if the brain is entirely occupied looking at something to our left, it might miss a predator sneaking up from the right. Thus, while some visual data (like the color and shape of objects) seem to be processed holistically, the task shared by both hemispheres, the location of things seem to be independently handled by one side or the other, depending on its location in space.

What this new study indicates, then, is that if we start tracking something to our left, say a car, with our right brain hemisphere, but that car keeps moving and ends up to our right, the right side of the brain hands that tracking task off to the left side of the brain seamlessly enough that we don’t realize it’s happening, and we don’t experience a glitch in our visual experience.

There seems to be a small performance cost to this handoff (more brain processing resources required), and interestingly, the researchers noted an increase in resource usage both in the hemisphere doing the handing off, and in the hemisphere receiving the task, which suggests there’s an anticipatory process at play as the side that was tracking stays mobilized in case it needs to take over again, and the side that’s about to start tracking musters its resources to prepare for the transition.

All of which is potentially useful because of what it tells us about the relationship between our brain hemispheres, and because we often see breakdowns in hemispheric synchrony in people who suffer from anxiety, depression, obsessive-compulsive disorder, dyslexia, and Alzheimer’s, among other brain-altering conditions.

This sort of fundamental understanding may thus help us better understand those conditions, as well as helping fill in the (many and massive) gaps in our general understanding of our brains.