system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do cats stare at blank walls?

I've seen my cat, my friends' cats, and cats on the internet stare at blank walls, seemingly looking at nothing. Why do they do this?
gpt
A cat is unlikely to be staring at nothing rather an insect or even a trivial thing like dust or the play of the light. Cats are very keen hunters, with a strong instinct for tracking such things so they just can't help it.