But the most important thing about Ellie is not her skill at gently probing all the people her scientist brings into the lab to talk to her. Her real value, the reason she was built at all, is her skill at taking and analyzing thousands of measurements of those people.

Under the wide screen where Ellie’s image sits there are three devices. A video camera tracks facial expressions of the person sitting opposite. A movement sensor — Microsoft Kinect — tracks the person’s gestures, fidgeting and other movements. A microphone records every inflection and tone in his or her voice. The point, Rizzo explains, is to analyze in almost microscopic detail the way that people talk and move — to read their body language.

“We can look at the position of the head, the eye gaze,” Rizzo says. Does the head tilt? Does it lean forward? Is it static and fixed?” In fact Ellie tracks and analyzes around 60 different features — various body and facial movements, and different aspects of the voice.

The theory of all this is that a detailed analysis of those movements and vocal features can give us new insights into people who are struggling with emotional issues. The body, face and voice express things that words sometimes obscure.