Stimulus Facial Hair Impairs Unfamiliar Face Matching Performance

Many identification tasks require human observers to decide whether the photograph on an identification document matches the person presenting it for inspection. Though this is a common task, average unfamiliar face matching accuracy in laboratory tests is often between 60-90%, even when the photographs are front facing, relatively high quality, and unobstructed. Unnatural obstructions such as reading glasses and surgical face masks further impair the accuracy with which two faces can be matched. Here we examined whether natural facial hair, which covers a similar area of the lower face as a surgical mask, also affects human performance in an unfamiliar face matching task. In Experiment 1, facial hair impaired unfamiliar face matching accuracy by approximately 8%, regardless of whether one or both faces in the pair wore a beard, compared to when the same identities were shown cleanshaven. Results from Experiment 2 indicated that natural facial hair does not provide identity information that participants used reliably in the matching task, with similar levels of accuracy found whether faces wore natural beards, fake beards, or surgical masks. Our findings suggest that beards are obstructions of the lower face that can pose a challenge to accurate identity verification.