In a laboratory experiment, we use a public goods game to examine the hypothesis that human subjects use an involuntary eye-detector mechanism for evaluating the level of privacy. Half of our subjects are "watched" by images of a robot presented on their computer screen. The robot-named Kismet and invented at MIT-is constructed from objects that are obviously not human with the exception of its eyes. In our experiment, Kismet produces a significant difference in behavior that is not consistent with existing economic models of preferences, either self- or other-regarding. Subjects who are "watched" by Kismet contribute 29% more to the public good than do subjects in the same setting without Kismet.
Keywords: Altruism; Proximate causation; Public goods; Reciprocity; Tinbergen.