APA Dictionary of Psychology

the mimicking of another individual’s stance, gestures, or other nonverbal behaviors, whether fully or partially. For example, if one person crosses their arms during a conversation and the other person subsequently does the same, then postural mirroring has occurred. The phenomenon tends to be nonconscious and may even induce affective similarities in participants (e.g., a person mirroring the posture of someone who is anxious may then feel anxious, too). Also called postural echo. See mirror neuron.