Facial expressions in response to a highly surprising event exceeding the field of vision: a test of Darwin's theory of surprise

Abstract

According to the affect program theory of facial displays, the evolutionary core of the human emotion system consists of a small set of discrete emotion mechanisms that comprise motor programs for emotion-specific facial displays. However, research on surprise has found that surprising events often fail to elicit the associated facial expression (widened eyes, raised eyebrows, mouth opening). The present study tested a refined Darwinian account of the facial expression of surprise, according to which surprising events cause widened eyes and raised eyebrows if they exceed the field of vision, as these facial changes increase the visual field and facilitate visual search. To test this hypothesis, we staged a surprising event that engulfed the field of vision: When the participants left the laboratory, they unexpectedly found themselves in a new room, a small chamber with bold green walls and a red office chair. In addition, to explore the role of social context for the expression of surprise, in two of three experimental conditions, a stranger or a friend they had brought to the experiment was sitting on the chair. The results provided no support for the Darwinian account of the facial expression of surprise. A complete expression of surprise was observed in 5% of the participants, and the individual components of the expression were shown only by a minority, regardless of social context. These findings reinforce doubts about the adequacy of affect program theory for the case of surprise.