Consider that the simplest social interaction between two people requires performing an astonishing array of tasks: interpreting what the other person is saying; reading body language and facial expressions; smoothly taking turns talking and listening; responding to what the other person said; assessing whether you’re being understood; determining whether you’re well received, and, if not, figuring out how to improve or remove yourself from the situation. Think of what it takes to juggle all this at once! And that’s just a one-on-one conversation. Now imagine the multitasking required in a group setting like a dinner party.
So when introverts assume the observer role, as when they write novels, or contemplate unified field theory—or fall quiet at dinner parties—they’re not demonstrating a failure of will or a lack of energy. They’re simply doing what they’re constitutionally suited for.