Dog vision is different from human vision in several ways. They can't distinguish red and green.
And they don't have sharp focus in a central area of the retina. Instead of concentrating photoreceptors in the fovea centralis, which gives us humans very detailed and color-sensitive vision in the pinpoint center of our attention, they have a broader area of focus.
Dog vision may not be as sharp or as colorful as ours, but it's better at tracking fast-moving objects, because their eyes are optimized to respond quickly.
Our photoreceptors have to recharge at a rate of about 60 times per second. This "flicker fusion" threshold is the recharge rate that allows us to perceive a steady image on a flickering source like a TV screen.Watching video that refreshes at 30 or 25 frames per second will pass for stable reality for us—but not for a dog. As dog expert Alexandra Horowitz says, "Dogs have a higher flicker-fusion rate than humans do: seventy or even eighty cycles per second. This provides an indication why dogs have not taken up a particular foible of persons: our constant gawking at the television screen," which is not fast enough for dog vision. "They see the individual frames and the dark space between them too, as though stroboscopically. This—and the lack of concurrent odors wafting out of the television to engage them. It doesn't look real."
Their fast flicker-fusion rate and reaction time also explains why dogs are so good at catching flying frisbees or tossed chunks of cheese.
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From the book: Inside of a Dog: What Dogs See, Smell, and Know
by Alexandra Horowitz
by Alexandra Horowitz
5 comments:
I am sure Smooth he prefers reality over TV.
He is a smart boy.
That’s great. What about cat vision though? Colorblind as well? And our cat will watch the tv as well. But if his frame rate is crazy he might be watching just trying to figure out why we are so enamored.
My late dog Miles, who was a hound mix, would ignore the TV. The exception would be nature programs that were about wolves. When he heard them howling he would stare at the TV screen turning his head from side to side. Sometimes he would whimper at the howling. The sound of the wolves definitely upset him to some extent.
My dog is very good at recognizing animals on TV. I'm not sure this theory is true, I suspect that the real reason may be that most dogs ignore visual input that has no smell to go with it. My dog is the only dog I've seen to act like this, he even responds to cartoon dogs.
Lindsay, I've heard from a few other people saying just what you're saying, and one can't deny the evidence of seeing a dog clearly watching TV. I remember seeing a video of a bulldog closely watching a cartoon about dogs.
I don't know if it's because of the frame rate issue, but our husky mix Smooth definitely doesn't care about video on a computer even if it's a vid of other dogs, but he's keenly interested in the sound coming from the speakers.
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