Introducing the brain: speed of eyesight (Introduction)

by David Turell , Friday, December 29, 2023, 00:26 (328 days ago) @ David Turell

Follow the pitched ball if you can:

https://www.newscientist.com/article/2409000-peoples-speed-of-sight-varies-and-this-may...

"Our speed of sight is also known as the flicker fusion threshold, because if a light is flashing on and off at a frequency above someone’s threshold, it appears to them to be shining steadily.

“It’s comparable to how many ‘frames per second’ our visual system processes,” says Haarlem.

"This threshold varies widely in the animal kingdom, being higher in creatures that can move faster, especially if they hunt other speedy animals. For instance, the peregrine falcon, the fastest creature on Earth thanks to its plummeting hunting dives, has a flicker fusion frequency of about 130 images per second, or 130 hertz.

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'To find out how much this ability varies between individuals, Haarlem and his colleagues asked 88 people from the university to view a flickering light, the frequency of which could be adjusted. They used three methods: asking the person to turn the frequency up until the light stopped flickering, asking them to turn the frequency down until flickering began or asking them to say whether the light was flickering over a series of randomly chosen frequencies.

"The participants repeated all the tests on three occasions to see if their threshold changed from day to day.

"Using the last method, thought to be the most accurate, the average flicker threshold for the whole group was about 50 Hz, but it varied from 34 to 61 Hz.

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“If something were to fly past your eyes very rapidly, but you have a threshold high enough to capture that image, your brain would probably turn it into a blur going in a certain direction,” says Haarlem. “Whereas in someone with a very low threshold, that flying object might not be captured at all.”

"It isn’t known what causes people’s flicker threshold to vary, but it could involve innate features of the cells at the back of the eye that react to light or the parts of the brain that process vision. “There are multiple levels of processing that get an image presented to our conscious perception,” says Haarlem. “I think it’s a combination.”

“'This is a very nice study because it’s completely new,” says biologist Simon Potier. He speculates that people may be able to increase their flicker threshold with training, for instance, if they play fast-moving sports such as baseball or squash."

Comment: it may depend upon brain reception speed or bioreaction time in the retina, or a mix of both.