Dogs vs. puppet

Interesting. The dogs know of course that they aren't dealing with a real dog, and that's what spooks them.

There's a guy down the street from me who has made a "dog" out of old rubber boots and chained it to the fire hydrant on his lawn. The first time my dog saw it, she was utterly spooked: looks like a dog but doesn't move and doesn't smell like a dog.

Similar reactions when dogs are introduced to duck decoys for the first time: look like birds but don't act like birds.

I think this is the dog equivalent of the "uncanny valley."
http://en.wikipedia.org/wiki/Uncanny_valley