1. They don’t like people.
2. They’re unfriendly, standoffish and aloof.
3. They lack emotions, and feel thing less intensely than others.
4. They’re not interested in what matters to other people – they don’t share their excitement or feel their pain.
5. They’re not easily hurt by others. You can exclude them, leave them out or walk over their feelings and it won’t affect them deeply.
6. They’re more serious, and have less of a sense of humour than extroverts.