The first televisions sold refreshed the image on the screen about 60 times per second. The way humans perceive time, that looks like a continuously moving image. To a dog and most other animals, that looks like a flickering series of still images. Predator and prey animals process information faster than we do; that’s why they have such good reflexes. (Newer TVs have much faster refresh rates, so they can look realistic to animals).
From The Economist:
It is called the critical flicker-fusion frequency, or CFF, and it is the lowest frequency at which a flickering light appears to be a constant source of illumination. It measures, in other words, how fast an animal’s eyes can refresh an image and thus process information.
For people, the average CFF is 60 hertz (ie, 60 times a second). This is why the refresh-rate on a television screen is usually set at that value. Dogs have a CFF of 80Hz, which is probably why they do not seem to like watching television. To a dog a TV programme looks like a series of rapidly changing stills.
You may think you’re smarter than your dog, and maybe you are, but your dog processes information much faster.
It’s relativity of a different sort. Consciousness is a weird thing, and it’s even weirder when you consider what consciousness is like for other living things. You are to a deer as a turtle is to you.