Audience, conceived by rAndom International, is an installation consisting of around 64 head-size mirror objects. Each object moves its head in a particular way to give it different characteristics of human behaviour. Some chat amongst themselves, some shy away and others confidently move to grab your attention.
When members of the audience occupy the space, the mirrors inquisitively follow someone that they find interesting. Having chosen their subject, they all synchronise and turn their heads towards them. Suddenly that person can see their reflection in all of the mirrors. They will watch this person until they become disinterested, then either seek out another subject or return to their private chatter. The collective behaviour of the objects is beyond the control of the viewer, as it is left entirely to their discretion to let go of their subject.
More tech info: http://www.openframeworks.cc/gallery/audience