The own-age bias stems from distinctions in using holistic and part-based information for own- and other-age faces

It is well established that individuals recognize faces of their own age better compared to others, known as the own-age bias. However, its underlying mechanisms, especially the roles of holistic and part-based information, remain underexplored. In a variable viewing position paradigm. participants fixated on either the left or right eye of a target face and then chose the previously seen face from four options: the target, a face with congruent peripheral but incongruent central features (holistic match), a face with congruent central but incongruent peripheral features (part-based match), and a fully incongruent face. Undergraduate participants were tested with upright (Experiment 1) and inverted (Experiment 2) faces of young adults (20-year-olds) and children (4-year-olds). Results showed that for upright faces, participants achieved higher accuracy for own-age faces versus other-age faces, demonstrating the own-age bias, and this bias was not observed for inverted faces. Additionally, for upright faces, participants made more holistic errors on adult faces than child faces, but more part-based errors on child faces than adult faces. These error patterns disappeared for inverted faces. The findings suggest that the own-age bias results from a nuanced adjustment in face processing that involves both holistic and part-based information.