That one is fundamental attribution error, I think. The real reason you didn't chat with neighbors is because you do not repeatedly bump into your neighbor in spontaneous circumstances on a regular basis - even very social people often don't chat with neighbors. It's more about circumstance than personality.
This thread is for asking any questions that might seem obvious, tangential, silly or what-have-you. Don't be shy, everyone has holes in their knowledge, though the fewer and the smaller we can make them, the better.
Please be respectful of other people's admitting ignorance and don't mock them for it, as they're doing a noble thing.
To any future monthly posters of SQ threads, please remember to add the "stupid_questions" tag.