Hey baby, what's "up"? One- and 3-month-olds experience faces primarily upright but non-upright faces offer the best views.

Experience has been theorized to shape how we process faces. Frequent face types are better discriminated and processed using expert-level holistic strategies while less frequent types are less well discriminated and processed using less mature featural strategies. Although experience is probably influencing the development of face processing, it is unclear what aspects of experience are most influential. The current study utilized infant-perspective head-mounted cameras to capture infants' daily lives at 1 and 3 months of age to measure the perceptual qualities of frequent and infrequent face types. We examined experience with upright (i.e., frequently experienced) and inverted (i.e., infrequently experienced) faces. A large majority (88%) of all face exposure was to upright faces. Most faces, regardless of orientation, were viewed near to the infant, alone in the field of view, and in a frontal viewpoint (i.e., an "ideal view"). Although they were less frequent than upright faces, proportionally more non-upright faces were viewed in an "ideal view". At this young age, nearly all faces, even non-upright faces, are seen in ways that facilitate processing.