Why is Jared Leto more refined than Tom Cruise? The role of stability in developing parsimonious facial representations.

The facial information we use to memorise large numbers of faces is unclear despite decades of experimentation. We developed a theory that assumes representations are cost-efficient and include different diagnostic features in different faces, regardless of familiarity. Features that remain stable over encounters are diagnostic and so they receive more representational weight. Importantly, to decrease storage demands, coarse information is privileged over fine details. This creates parsimonious facial representations that refine over time if appearance changes. The theory predicts that representations of people with a consistent appearance (e.g., Tom Cruise) include stable coarse extra-facial features, and so their inner features need not be encoded with the same high resolution as those of equally famous people who change appearance frequently (e.g., Jared Leto). In three preregistered experiments, participants performed a recognition task in which we controlled actors’ appearance (variable, consistent) and popularity (higher, lower). In line with our theory, in less popular actors, stable extra-facial features helped remember consistent faces compared to variable ones. However, in popular actors, variable actors were better recognised than consistent ones, suggesting representations of the former had refined over time. We will discuss broader implications of our theory for the field.