Just to get pedantic, positive reinforcement means you are adding something to the environment with the goal of affecting behavior. Negative reinforcement means something has been removed from the environment to affect behavior. Not the same thing as reward and punishment. A negatively worded message is still technically positive reinforcement.
I'm not sure if you can consider a sign reinforcement though, because it is usually presented before the desired or undesired behavior occurs....
Yep, I'm fully aware of the behavioral theory behind it and the four quadrants. To the layman it's easier to talk about Reinforcement versus Punishment alone, since the two main branches share most of the common effects, and of which (at least in animal training) Positive Reinforcement with cues (clicker) appears to be the most effective. I realize I might have mixed them up above, sorry about that.
I actually think about positive wording versus negative wording to be a prime example of punishment versus reinforcement; with negative wording the interpretation (mine anyway, without much analysis) is a pre-emptive punishment directed directly at me for an undesired behavior that is an option, whereas a positively worded sign is pre-emptive positive reinforcement for good behavior that I might consider. I get rewarded/positively reinforced for good thought versus punished for bad thoughts, and it turns out the punishment (and side-effects thereof) applies whether or not I actually had the thoughts or not (citation needed, etc.). Really interesting to think about.
I'm not sure if you can consider a sign reinforcement though, because it is usually presented before the desired or undesired behavior occurs....
https://en.wikipedia.org/wiki/Reinforcement