Be observant. Perceiving how other people are feeling is a critical component of emotional intelligence, and it’s particularly key in negotiations (as Adam Galinsky and his colleagues have found). So tune in to your counterpart’s body language, tone of voice, and choice of words. When her verbal and nonverbal cues don’t match up, ask questions. For example, “You are telling me you like this outcome, but you seem uneasy. Is something making you uncomfortable?” Or “You say you’re angry, but you seem somewhat pleased. Are you truly upset about something? Or are you trying to intimidate me?”
Asking pointed questions based on your perceptions of the other party’s emotional expressions will make it easier for you to understand her perspective (a task people are shockingly bad at, according to research by Nicholas Epley). It will also make it difficult for a counterpart to lie to you; evidence suggests that people prefer to tell lies of omission about facts rather than lies of commission about feelings.