system
Given the following post, respond as if you're commenting on Reddit:
human
Why do I have to think for a second about left vs. right, but up vs. down comes to me immediately? It's not just me, right?
gpt
Up and down are defined by the direction of gravity. Things always fall down, never up. Your feet are always down not up. Your head is alway up, not down. But left and right are more or less symmetric.