Orientation Effects Support Specialist Processing of Upright Unfamiliar Faces in Children and Adults.

It is considerably harder to generalize identity across different pictures of unfamiliar faces, compared with familiar faces. This finding hints strongly at qualitatively distinct processing of unfamiliar face stimuli—for which we have less expertise. Yet, the extent to which face selective versus generic visual processes drive outcomes during this task has yet to be determined. To explore the relative contributions of each, we contrasted performance on a version of the popular Telling Faces Together unfamiliar face matching task, implemented in both upright and inverted orientations. Furthermore, we included different age groups (132 British children ages 6 to 11 years [69.7% White], plus 37 British White adults) to investigate how participants' experience with faces as a category influences their selective utilization of specialized processes for unfamiliar faces. Results revealed that unfamiliar face matching is highly orientation-selective. Accuracy was higher for upright compared with inverted faces from 6 years of age, which is consistent with selective utilization of specialized processes for upright versus inverted unfamiliar faces during this task. The effect of stimulus orientation did not interact significantly with age, and there was no graded increase in the magnitude of inversion effects observed across childhood. Still, a numerically larger inversion effect in adults compared to children provides a degree of support for developmental changes in these specialized face abilities with increasing age/experience. Differences in the pattern of errors across age groups are also consistent with a qualitative shift in unfamiliar face processing that occurs some time after 11 years of age. Public Significance Statement: This study supports a contribution of specialized processing mechanisms for unfamiliar face processing that operate selectively for faces presented upright, compared to inverted in a similar manner to those seen for familiar faces. Observed orientation effects did not increase between 6 and 11 years of age, but were much stronger in adults, which provides a degree of support for developmental changes in specialized unfamiliar face abilities with increasing age/experience. [ABSTRACT FROM AUTHOR]