The Eye Direction Detector (EDD) and the Shared Attention Mechanism (SAM): Two Cases for Evolutionary Psychology
University of Cambridge
To be a viable hypothesis about human psychological architecture, the design proposed must be able to meet both solvability and evolvability criteria [emphasis added]: It must be able to solve the problems that we observe modern humans routinely solving and it must solve all the problems that were necessary for humans to survive and reproduce in ancestral environments.
-- Tooby & Cosmides, 1992, p. 110
Imagine that you are walking onto a crowded train. You see a remaining empty seat, so you go across and sit down. You get out your book, and settle into it. During the journey, you become aware of a feeling that someone is looking at you. You glance along the carriage and, sure enough, someone is looking at you. As soon as you make eye contact with this stranger, he looks away. To my mind, this phenomenon is rather striking in that it is not immediately obvious how you would have known that someone was looking at you if you were already engaged in another activity. One possibility is that as the train was going along you were occasionally rapidly scanning the other passengers' faces. Given that there was quite a crowd, perhaps your perceptual system only superficially processed those faces whose eyes were directed away from you, because to have processed each and every face in any deeper way would have led to information overload, and would be of little adaptive value. But among that sea of faces there was one whose eyes were directed at you, which your perceptual system processed in more detail. In this chapter, I discuss the evidence that "eyes looking at me" are especially salient.