Broadly tuned face representation in older adults assessed by categorical perception.

Studies of face recognition in older adults (60 years of age and older) report increases in false alarms over younger adults (usually 18-30 years of age), but no age differences in hits. To examine this phenomenon, we compared older and younger adults in categorical perception of faces. We hypothesized that face representations in older adults would be broadly tuned, resulting in overlapping representations, manifested by a shallower slope in identity categorization than in younger adults, and age-related reductions in the advantage for between-categories, as compared with within-category, face discrimination. We morphed faces to change linearly from one identity to another. We used familiar or unfamiliar faces in separate conditions to examine the role of familiarity. Categorical perception was assessed in an identity-classification task and a discrimination task. Older adults showed a shallower slope and poorer discrimination compared with younger adults, and both groups exhibited better performance with familiar than unfamiliar faces. Enhanced discriminability for between-categories as compared with within-category faces was seen for both familiar and unfamiliar faces in younger adults, but only for familiar faces in older adults. The more broadly tuned representations of unfamiliar faces in older adults may lead to misidentification and greater false alarms for unfamiliar faces, but not for familiar faces.