The box contained a little device that delivered a tiny electric shock. The participants first experience of this work comes after the initial physical contact.
There was a sculpture inside the volume that was attached to an electric shock generator. When someone put his/her hand inside the volume and touched the surface of the inner sculpture a slight electric shock was randomly given.
We are dealing with two reactions; one is for the visitor and another for the volume. The work was an experiment in studying the conservative behavior(reaction) of people in the face of the unseen object.