Similar to our social media feeds, our brains are constantly loading up on rich visual stimuli. However, according to new research from the University of California, Berkeley, instead of seeing the latest image in real time, we actually see previous versions because our brain refresh time is about 15 seconds. The findings, published in Science Advances, add to a growing body of research on the mechanism behind the “continuum field,” a function of perception in which our brain integrates what we see on a consistent basis to give us a visual sensation. More.
“If our brains were always evolving in real time, the world would be a tense place with constant fluctuations in shade, light, and movement, and we would feel like we were hallucinating all the time,” said study senior author David Whitney. Professor of Psychology, Neuroscience, and Vision Sciences at the University of California, Berkeley. Instead, the study’s lead author Mauro Manasi said, “Our brain is like a time machine. It takes us back in time. It’s as if we have an app that integrates our visual inputs every 15 seconds into a single impression so we can deal with everyday life.” , an assistant professor of psychology at the University of Aberdeen in Scotland and a former postdoctoral fellow in the Whitney Laboratory at the University of California, Berkeley.
For the study, Manasseh and Whitney looked at the mechanism behind changing blindness, in which we don’t notice subtle changes that occur over time, such as the difference between actors and their funny pairs, or movie blunders. They recruited about 100 study participants through Amazon Mechanical Turk’s crowdsourcing platform and had them watch close-ups of faces that transform according to age or gender in 30-second time-lapse videos.
The images in the videos didn’t include head or facial hair, just the eyes, eyebrows, nose, mouth, chin, and cheeks, so there would be little indication, such as receding hair lines, on the ages of the faces. When participants were asked to identify the face they saw after watching the video, participants almost consistently chose a frame they saw in the middle of the video rather than the last, which would have represented the most updated image.
“One could say our brain is stalling,” Whitney said. “Continuously updating images takes a lot of work, so they stick to the past because the past is a good indicator of the present. We recycle information from the past because it’s faster, more efficient, and less work.” In fact, the results indicate that the brain operates with a slight delay when processing visual stimuli, and this has both positive and negative effects.
“Delays are significant to prevent us from feeling bombarded by visual input in everyday life, but it can also lead to life-or-death consequences when surgical precision is needed,” Manase said. “For example, radiologists are examining tumors and surgeons need to be able to see what’s in front of them in real time; if their brains bias what they saw less than a minute ago, they might miss something.” Whitney said that changing blindness in general reveals how the domain of continuity is a purposeful function of consciousness and what it means to be human.
“We are not blind in the literal sense of the word,” he said. “The slowness of our visual system in updating can blind us to immediate changes because it catches our first impression and draws us into the past. Ultimately, though, the field of continuity underpins our experience of a stable world.” (Ani)
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