Before revision:  Hence, people are normally not only pay attention to  what their interlocutors are saying but also try to inspect their visual appearances, including faces, to  find any signs that indicate whether the person is telling the truth or not.
After revision:  Hence, people are normally not only pay attention to both what their interlocutors are saying but also try to inspect their visual appearances, including faces, to find any signs that indicate whether the person is telling the truth or not.