As a form of nonverbal signaling, body posture creates an impression of attitude. Posture can tell how interested, respectful, or open to ideas someone is. Postural cues can suggest affinity or distaste.
When someone is interested while sitting, they lean forward and draw back their legs. Conversely, someone bored adopts a lethargic posture: leaning back, dropping the head, leaning it to one side and supporting with one hand, and stretching out the legs.
Agreement and openness are parallel postures: the body is relaxed, perhaps leaning to one side, arms down or out. Disagreement is displayed by a vigilant, closed posture: head erect, arms folded, legs crossed.
Posture can indicate dominance or submission. A man standing straight, chest forward with hands on his hips is showing dominance. Conversely, making oneself smaller can appease and inhibit human aggression. As with other mammals, such postures are innate biological behaviors.
Full attention is displayed by facing another person with head and body. Between equals, this is an indication of liking rather than respect.
Similarity in postures – termed postural congruence or postural echo – also signals liking. Mirror-image postural echoes indicates interpersonal rapport. Postural dissimilarity often indicates differences in attitude or status.
In social situations people control their facial expressions better than their bodies, which can give away what they really feel. This is nonverbal leakage.