On: I am a neuropsychologist. Ask me (almost) anything.

[Ardit20]

I think it is more complicated than that. I see for example posters I can down vote and other posters I can not.

[petercooper → Ardit20]

This probably isn't the full picture, but you can't vote down comments left directly in response to your own comments (for obvious reasons), nor can you vote down comments over a certain age or that are already of a very low score.