Mehrabian's work on immediacy established that posture and orientation communicate attitude independently of speech: forward lean and open limb positions read as engagement, while closed arms and away-orientation read as withdrawal. Posture is coarse, robust to poor image quality, and codable at lower resolution than gaze or facial affect — which makes it the most practical nonverbal channel for reviewing recorded sessions.
Intended for detection studies. Draw a box around the person's torso (not just the head) and code the posture it shows. Code each person in the frame separately.
These are not mutually exclusive in practice. A forward lean with folded arms is a real and informative combination; code both rather than choosing. Openness and lean are different axes — one is about limb configuration, the other about trunk angle.
Read posture, not furniture. Someone in a chair with fixed armrests, or holding a clipboard, has their options constrained. Where the setting forces a posture, the code says less about attitude — note it in the rationale rather than inflating the rating.
Severity is clarity. A torso cropped at the shoulders cannot support an openness code. If limbs and trunk angle are not both visible, rate Partial.