Just like any other incredible piece of computer technology, your brain needs to hit the refresh button once in a while. Taking frequent productivity breaks, making sure to keep the blood pumping with walks, (running), or meditation are all familiar ways of hitting that magical refresh button, so it might surprise you to know that your brain is refreshing itself without any conscious effort from you—about every 15 seconds!
These aren’t the same type of mental health breaks we force on ourselves for a personal refresh, however. Instead, it’s the only way the brain can actually keep up with the demands of the real world. Making sense of all the motion, colors, senses, and light is actually a full-time job for the brain, and it’s protecting itself by freezing visual information in place and not updating it for a full 15 seconds.
Whether you like to think of it as a delay or a refresh, the brain is basically taking snapshots of the current environment and using that snapshot rather than a constant influx of the current time. Yes, you heard correctly: what you think is happening this very minute, in the present, is actually 15 seconds behind!
Researchers were intrigued with the fact that small changes are almost imperceptible to the human brain, such as slight changes in color or the way individual frames of a movie flow together. To test their theory, they put participants in a study that focused on “change blindness.”
The participants were shown time-lapse videos in 30 second segments with faces which were changing with age (a time lapse of aging). Only the features in the center of the face were shown to keep the faces from being too distinct individually. After they saw the videos, they were asked to pick out the face they had just seen, and they almost always picked an image of the face which was seen half-way through the time lapse, rather than the one at the end they had just seen.
It’s really a way for the brain to be as efficient as possible when filtering through the visual stimuli of the world, and the changes are ever so slight. Without it, we'd be lost in the mix of light and sound, and researchers say we wouldn't be able to cope or function. It’s usually something we’ve grown so adapted to that we don’t even notice it, except in those situations when we’re relying on extreme precision, such as driving. A good reminder to take an extra few seconds at a stop sign, and a powerful reminder that we don’t always see the whole picture.
Mauro Manassi, David Whitney. Illusion of visual stability through active perceptual serial dependence. Science Advances, 2022; 8 (2) DOI: 10.1126/sciadv.abk2480