Reflecting Body Language
Echoing the body language of a person you interact with can be interpreted as empathetic. For example, if you talk to someone who leans forward with uncrossed legs and open arms, if you reflect the same pose, you are sending the message: "I am engaged in this interaction, and you have my attention."
Be prudent when reflecting, though. It could backfire and be interpreted as mocking. It's also not helpful to reflect a pose that has negative elements. For example, when talking to someone who leans back with arms crossed behind the head, it would be counterproductive to reflect the same negative pose. Instead, you might succeed in drawing the other person more fully into the conversation by leaning forward and engaging eye contact.