Depends who it is.
If it's just someone I know, then I probably won't stop.
If it's an an acquaintance I do not like and need not pay much respect/need not pretend to like them, I won't stop either. (Might not even be saying 'hi' then if I want to be really rude.)
If it's an acquaintance and if we both feel it's important to keep a neutral or positive relationship, then I stop and have a super short chat.
If it's a friend, a family member or whatever, I stop to chat with them.
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Autism + ADHD
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The trouble with having an open mind, of course, is that people will insist on coming along and trying to put things in it. Terry Pratchett