How do they know that? Did they ask a cat? :LOL3: Personally I don't think it's true or they would treat mice the same as kittens. I think all animals know that they're different from other species.
My fact: Cat can see blue, purple, green and yellow tones. Red, orange, and brown are likely seen as shades of gray. So if your kitty likes the blue felt micies best, you know why!