Faces and facial expressions do not pop out.

Subjects were asked to detect faces or facial expressions from patterns with a variable number of nonfaces or faces expressing different emotions. In most tests, reaction time was found to increase steeply with sample size, thus indicating serial-search characteristics for the patterns tested. There were, however, considerable differences in the slopes of the graphs (search time versus sample size), which could be attributed to visual (but not face) cues that are discriminated at similar speeds. Slopes did not change when patterns were presented upside down, although such a modification strongly affects the perception of faces and facial expressions.