Nonverbal behavior like body movements and posture, facial expressions, eye contact, hand gestures, and tone of voice all contribute to how we communicate and understand each other.
With the times changing and technology taking over, interactions with machines are already in action. When it comes to a human–machine interaction, it would be plausible to design the interaction interface to be as natural and comfortable for a human as possible. For example, we would like a robot to say kindly “Hello” to a smiling human or to approach a human waving his hand. It is then essential for this purpose that a machine can record and correctly interpret the body language of a human.
K. Lai, J. Konrad and P. Ishwar, “A gesture-driven computer interface using kinect”, Proc. IEEE Southwest Symp. Image Anal. Interp., pp. 185-188, Apr. 2012.
Non-verbal communication, which includes body language, facial expressions, and vocal intonation, conveys a human’s intent better than verbal expressions, especially in representing changes in affect (Collett P, Marsh P, O’Shaughnessy M). For instance, while studying and conducting user research for a sensitive topic, especially conducting semi-structured or structured interviews, not always will the participant(s) convey explicitly and verbally. It is very important to observe the body language, annotate the feelings or expressions and make notes to make sense of it later. This will help a design researcher understand the participant and their behavior without actually making them uncomfortable during the research study.
Albert Mehrabian psychologist, an expert in body language https://www.psych.ucla.edu/faculty/page/mehrab