When you think of the word "dog", what type of dog do you picture in your mind? how do you know that a type of dog is a dog and not a bird? why did you picture that particular type of dog?

Explanation:

When i think of the word Dog, i can imagine a small cute puppy in my mind who is in my lap playing with me.

I know that this is a dog because the structure of every specie on the earth is different. Dogs have long teeth, they have a tail, they have comparatively big ears, they have paws and most importantly, they can fly. So i know that this is a dog, not a bird, because all birds can fly and dogs don't fly.

I picture that particular type of dog in my mind because i had that puppy as a pet in my childhood who later died of some disease. My puppy always comes in my mind whenever i imagine a dog.