My only experience with this was with a puppy I had at the same time I had a mirror that sat on the floor and leaned up against a wall. My puppy tried like crazy to get the other puppy to play with him and never could get anything to happen. Finally, he just gave up and never again gave a crap about that other puppy.
The other thing missed here is that what we are looking at is an abstract construct – a bunch of pixels or reflected light. Dogs don’t really do abstract.
But that’s plainly not true. Several people here posted how their dogs react to TV. One of ours always reacts to a dog on the TV, more so if the image is close to life-size. He tries to get their attention, he jumps up on the TV stand. The other dog could care less.
I’ve always thought it was whether the individual dog goes primarily by sight or smell. Primary smell dogs don’t recognize the TV image as a dog; sight dogs do.
We have two border collies. One of them never watches TV with us, and seems completey indifferent. The other one will sit with us throughout an entire show and watch intently, following the movements on screen. If an animal appears she’ll jump off the sofa and run up to the screen, where she gets confused because it devolves into pixels when you are right up to it (102" movie screen). Then she’ll run hack to the sofa and just start watching again.
We have a rather elderly cat that watches a lot of TV. Particularly programs with small animals or birds moving around. He will sometimes, if a picture of an aquarium is on the screen, get up on the TV table and peek around in back to try to find out where all those little fishies are going. And high-pitched sounds will really get his interest.