Brain predicts before eyes see

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Brain predicts before eyes see
Brain predicts before eyes see

On Friday I dropped by a local park after work and spotted an immature Red-tailed Hawk sitting on a nest box on a pole and scanning the ground below for a potential prey. I took my position slightly below on a slope, away from it and waited. Then the bird dove down and I started tracking it. Soon it disappeared from view and I took my finger off the shutter.

Later when I looked at the photos on my computer I realized that I took seven extra frames after the bird disappeared from view. To illustrate the point I created this short video after stitching the frames together and introducing slight delay between frames. At 20 frames per second on Z9 that 7 frames amount to close to 300 ms - it took me that long to stop taking photos after the bird disappeared behind the slope. Some may call it reaction time. After the light hit the retina, it took about 30 ms to reach my brain which then took another 120ms to process before the command was sent to my finger to stop taking photos. But this also means we are always living in the past, I only 'saw' the bird disappearing 150 ms after it actually happened. Interesting dilemma.

So, how does a catcher catch a ball that is moving fast? By the time the catcher 'sees' the ball it has already gone past him in reality. A successful catch is still possible because brain extrapolates and predicts where the ball will be before eyes see it. Take a close look at the frames after the bird disappeared. One could see that I was still tracking downward (ground moved upward) because the brain predicted where the bird would be and my hands simply followed it. Fascinating, isn't it?

I also wondered if 300 ms reaction time in the field is good. So I took a test on my computer with color changing circle and my average reaction time came out to be 261 ms., a very respectable number compared to the average of 248 ms found in a group of 18-20 year old medical students. It's raining outside and I am stuck indoor, so I decided to write this up and created this benchmark to measure against as I grow old. And now go measure yours, see where you stand.

By the way, I could've set an alternate title as 'We are always living in the past'. I took the ideas from an article that I just read (theconversation.com/what-youre-seeing-right-now-is-the-pa...)

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Taken on: March 25, 2023
Tags: Everybody's photos tagged with Brain Teaser Brain Teaser Everybody's photos tagged with Red-tailed Hawk hunting Red-tailed Hawk hunting Everybody's photos tagged with Reaction Time Reaction Time
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