What is known about Persistence of Vision in various animals?
What is known about Persistence of Vision in various animals?
I'm curious about building cat toys that are impractically over complicated with Arduino/Maker stuff. Thus the casual curiosity about persistence of vision. I wonder if other animals have something like a different internal clock frequency where the image only forms at higher (or lower) frequencies than most humans.
I am a biologist but I’m warning you up front that I’m going off of memory on this one, and animal vision was never my area of specialization (except in evolutionary models, which I can get into but which don’t apply to your specific question).
Cat vision, as I recall, is optimized around two things - seeing in low light conditions and seeing motion. Cats can have a harder time focusing on stationary objects and I don’t believe they have a particularly high level of processing for visual detail.
It’s important to remember - especially when we’re talking about trying to reverse engineer what another species sees - that the phenomenon we refer to generally as “vision” is an incredibly complex process. It involves multiple cell types, chemical and physical processes, and things like memory, taste, and smell. You’ve probably seen comments on nasty rooms where people say “I can smell this picture,” or caught a whiff of a cologne or perfume that evoked powerful memories including being able to visualize the person you associated it with, even though they’re not actually in front of you.
The visual parts of your brain can be activated absent any input from your eyes (something those with PTSD can know all too well), and your eyes take in a huge amount of information that never makes it to the visual processing layers of your brain, because you simply disregard it.
So when we look at the cells in a cat’s eye, we’re only seeing (so to speak) a very tiny part of the story. We learn more when we start to study how cats respond to visual stimuli - how they hunt, how they play, how they explore their worlds - but it’s all a blind men and the elephant kind of thing. Plus, I have to imagine it’s pretty hard to get that kind of research funded.
Anyway, I’d keep that in mind when you do start finding papers on cat vision, and I’d recommend more comprehensive works on cat behavior in general, from which you can infer things about vision but will provide a more full context like I’m talking about.
If you’re thinking about building Rube Goldberg type machines for keeping cats entertained, I think you should just go for it. Experiment. Do note that cats have a huge amount of variability in what they find interesting or fun. Some will watch tv, others will chase a laser pointer or a feather on a string. I had one that would just sit and stare at absolutely nothing all day long and couldn’t be bothered with anything but head scratches and the occasional piece of chicken.
One thing that seems to be pretty popular is having a ball or something that skitters around while under a blanket or towel, but do be aware that you’re basically training them to bite your toes really really hard while you’re trying to fall asleep. I speak from experience on that.
Cats can out speed snakes. If they have an fps it must be super high
I don't have a source for it, but I recall hearing that yes, their eyes work at a different speed than ours, and that's part of why cats and dogs are generally not so interested in TV. Unfortunately I don't know what search terms might be useful here since I don't know if this has a technical name, but something like "refresh rate" or "fps" might help in the search.
Sometimes my cats will be interested in TV, especially if there are really interesting birds. One cat in particular was very interested in Felix the Cat cartoons.
I think I read somewheres that you need 240Hz monitor to reach flicker-fusion with parrots?
It was either 120Hz or 240Hz.
I lost flicker-fusion one time in a movie theatre when an onscreen character pulled a knife, & suddenly the screen was AVALANCHING my mind with discrete-frames, & they were jumping around ( my eyes were jumping-around, but my perspective, within my brain, had been jarred ). That even seemed to have lasted about 1 second.
There is some video, journalism or documentary or something, on dragonflies, and the person with the knowledge was saying..
~ we know how long it takes for each layer in a brain ( neural-network ) to process its layer's stuff, and we know from the short reaction-time of dragonflies that they're using 3-neurons-deep brain for navigating/hunting/reacting.
We don't know how. ~
I seem to remember that neural-signal in our biology runs at about .. 300km/h?
Something like that.
So, with all the circuitry being shorter in an always-smaller kind of animal, it may have a predictably-shorter flicker-fusion rate?
( within kind, so no extrapolating from humans to birds, e.g. )
Anyways, interesting question!
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