Change detection in an attended face depends on the expectation of the observer.

Sensitivity to a scene change during a brief interruption depends critically on a match between what the observer expects to see and the kind of change that occurs (Austen & Enns, 2000). The present study tested the generality of this conclusion using human faces, which are both socially more relevant and perceptually more configural than the compound letters tested previously. An experiment using the flicker technique examined sensitivity to two types of change: facial identity and emotional expression. Change detection was assessed when attention was either focused or distributed, the change was either expected or unexpected, and the faces were either upright or inverted. The main finding was that detection was expectation-dependent, even when only a single upright face was presented. Secondary findings with regard to attentional distribution and face inversion confirmed that observers were indeed engaged in face processing. We conclude that observer expectations critically influence the perception of single and fully attended human faces.