Abstract
Face-diets of observers living in racially-homogeneous environments are predominantly composed of own-race faces resulting in a lack of experience with other-race faces (Sugden et al. 2014; Oruc et al. 2019). According to the contact hypothesis, this, in part, leads to a marked impairment in the ability to recognize other-race faces, termed the other-race effect. However, the contact hypothesis does not predict what impact a racially-heterogenous face-diet with plenty of exposure to multiple face races may have on face expertise. To complement and extend the contact hypothesis, we propose three new models: (1) the experience-limited, (2) the capacity-limited, and (3) the enhancement hypotheses for the role of exposure in face expertise. Based on the experience-limited account native-level face recognition can be achieved for multiple face races with sufficient experience. On the other hand, the capacity-limited account predicts exposure to multiple face races may impact face expertise detrimentally. Lastly, based on the enhancement account exposure to a racially-heterogenous face-diet may confer some advantages in face expertise. Here, in two experiments, we compared face recognition in a dual-exposure group (N = 20) with sustained high exposure to Caucasian and East Asian faces to two mono-exposure groups (Ns = 20) with sustained exposure to either Caucasian or East Asian faces only. We found native-like recognition performance in the dual-exposure group regarding face memory and face inversion effect for both Caucasian and East Asian faces. Our results showed neither an advantage, nor a disadvantage for racially-heterogenous face exposure, hence supporting the experience-limited account of face expertise. Consequently, we conclude that exposure to multiple face races is not detrimental to face recognition ability. To achieve native-level face expertise, a racially-homogenous face diet is not a necessity.