The person you’re talking to is lying to you if he/she copies your body language closely and nods along in agreement. This is the conclusion of a new study carried out by a combined team of researchers from Aarhus University in Denmark and Arizona State University, USA. So if you suspect someone is lying about something, it would be wise to keep an eye on the person throughout the conversation.
Interested or bored, computers can judge one's level of interest. If someone is interested in what they're watching, body shows less involuntary movements.