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When you go for a walk, how does your brain know the difference between a parked car and a moving car? This seemingly simple distinction is challenging because eye movements, such as the ones we make when watching a car pass by, make even stationary objects move across the retina—motion that has long been thought of as visual "noise" the brain must subtract out.
Now, researchers at the University of Rochester have discovered that instead of being meaningless interference, the visual motion of an image caused by eye movements helps us understand the world. The specific patterns of visual motion created by eye movements are useful to the brain for figuring out how objects move and where they are located in 3D space.
"The conventional idea has been that the brain needs to somehow discount, or subtract off, the image motion that is produced by eye movements, as this motion has been thought to be a nuisance," says Greg DeAngelis, [...] "But we found that the visual motion produced by our eye movements is not just a nuisance variable to be subtracted off; rather, our brains analyze these global patterns of image motion and use this to infer how our eyes have moved relative to the world."
[...] "We show that the brain considers many pieces of information to understand the 3D structure of the world through vision, including the patterns of image motion caused by eye movements," says DeAngelis. "Contrary to conventional ideas, the brain doesn't ignore or suppress image motion produced by eye movement. Instead, it uses this image motion to understand a scene and accurately estimate an object's motion and depth."
This research has important implications for understanding visual perception, which informs how the brain interprets everyday activities like reading and recognizing faces. But it could also provide insight and new applications for visual technologies, such as virtual reality headsets.
"VR headsets don't factor in how the eyes are moving relative to the scene when they compute the images to show to each eye. There may be a stark mismatch between the image motion that is shown to the observer in VR and what the brain is expecting to receive based on the eye movements that the observer is making," says DeAngelis. This could be what causes some people to experience motion sickness while using a VR headset.
Journal Reference: Xu, ZX., Pang, J., Anzai, A. et al. Flexible computation of object motion and depth based on viewing geometry inferred from optic flow. Nat Commun 17, 1092 (2026). https://doi.org/10.1038/s41467-025-67857-4
(Score: 1) by khallow on Tuesday April 07, @05:04PM (3 children)
However, if the motion you are looking for is minute - like a bird in a distant tree or a black figure in a night landscape, it's easier to see motion by staring at one spot until something moves.
(Score: 2) by JoeMerchant on Wednesday April 08, @01:10AM
> if the motion you are looking for is minute - like a bird in a distant tree or a black figure in a night landscape, it's easier to see motion by staring at one spot until something moves.
There are a lot of "differential circuits" in and immediately behind the retina, specifically tuned to fire for changes - so yeah, if you can be still and get a constant image on the detection plate, you'll catch motion a lot more easily from that state than if you're scanning all over.
Although that scanning motion also produces "stream" data which can get compared against known streams - like listening to a melody and hearing a wrong note you can pick out the outlier from a dynamic time-series dataset as well - but that's not as sensitive to your "tiny differences" test.
What's hard to wrap your head around is how compound eyes like flies have process their visual fields. They have a lot of sensitivity to changes, and they can do optical navigation - but... differently.
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(Score: 1, Interesting) by Anonymous Coward on Wednesday April 08, @03:16AM (1 child)
> it's easier to see motion by staring at one spot until something moves.
Hmmm, I thought I read something (long ago) that the small, high frequency, eye motions perform something like a moving screen saver on an old CRT, keeping the retina elements from saturating (and then losing sensitivity)?
(Score: 1) by anubi on Wednesday April 08, @07:09AM
I got the idea it was much like the dithering we did on digitizers to increase the apparent resolution. We got several more bits by adding noise and statistical analysis .
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]