Human emotions and social interaction have a lot to do with body language — how our faces express what we're thinking and feeling, how our gestures are read by other people, and how we invade (or retreat from) each other's personal space. In fact, those movements and behaviors are so important that, if you map them onto an otherwise completely non-human, non-animal form, we'll start interpreting it as engaging with us — even if that form is nothing more than a moving stick.
This video, clips from a study that was published in 2011 by computer scientists at the University of Calgary, shows what test subjects did and said when they were left alone in a room with a stick-like robot, and asked to just think out loud and interact with the robot in whatever ways felt natural. Some people made friends. Others tried to fight it. And a few tried to talk it out of wanting to fight them.