Scientists have long known that our sensory processing must automatically screen out extraneous inputs — otherwise, we couldn’t experience the world as we do.
And automatic background subtraction, it turns out, can also manifest in intriguing, unexpected ways. Take a counterintuitive finding that [neuroscientist Duje] Tadin and his colleagues made in 2003: We’re good at perceiving the movements of small objects, but if those objects are simply made bigger, we find it much more difficult to detect their motion.
Recently in Nature Communications, Tadin’s team offered a tantalizing explanation for why this happens: The brain prioritizes the detection of objects that are more important for us to see, and those tend to be smaller. To a hawk hunting for its next meal, a mouse suddenly darting through a field matters more than the swaying motion of the grass and trees around it. As a result, Tadin and his team discovered, the brain suppresses information about the movement of the background — and as a side effect, it has more difficulty perceiving the movements of larger objects, because it treats them as a kind of background, too.
Read full, original post: Your Brain Chooses What to Let You See