How does an animal know it's hiding?

This is more or less a speculative question because we can’t confirm our guesses about an animal’s thoughts by direct verbal communication. However, some of us are very sensitive to the perceptions and mental states of animals.

While my son was vacuuming last night, I watched the cat come into the bedroom and hunker down under a chair that was draped with clothes. He was effectively invisible. I know he doesn’t like the sound of the vacuum cleaner, and that’s one of his favorite hideouts.

It occurred to me suddenly to wonder: how do animals know enough about the point of view of another creature—an onlooker—to know when they’re hidden and when they’re not?

Is it just a matter of instinctively feeling safer in a tight enclosure, or is there really any sense at all of what another being can see?