My husband is an ISTP and although he is a very private and independent person, he does display some extraverted behavior.

For instance, he knows all of our neighbor’s names and occupations and often chats with them and assists them with household repairs. (I don't know them or talk to them despite having lived in the neighborhood 5 years.)

Also, when we travel, I usually like to read alone in the hotel room in the evenings, but my husband likes to find a pub and chat with the locals.

Sometimes I wonder if he hasn't taken on some extraverted traits because someone in our family has to do it and it seems to be more difficult for me than him. He is less self-conscious than I am.