Masks wearing off: Changing effects of face masks on trustworthiness over time.

During the global COVID-19 pandemic, the wearing of face masks became a common practice, raising questions about how masks affect perceptions of and behaviour towards others. Numerous studies have explored the impact of face masks on perceptions of trustworthiness, but results have been mixed and it remains unclear whether masks influence perceptions via their social meaning or their effects on facial appearance. In this study, Australian participants (N = 363) rated a series of faces which were either masked, unmasked, or occluded by a non-mask object (computer) in terms of perceived trustworthiness in 2020, 2022, or 2023. The apparent trustworthiness of unmasked faces remained stable across years, but masked faces were rated significantly more trustworthy in 2020 compared to 2022 and 2023. Furthermore, ratings of masked faces, but not unmasked faces, were correlated with participants' attitudes towards wearing masks. Faces occluded by a non-mask object were perceived to be less trustworthy than masked faces. Together, results strongly suggest the increase in perceived trustworthiness of masked faces reported in numerous studies conducted during COVID-19 were driven by positive social meanings around mask wearing rather than by their effect on facial appearance.

Image variability and face matching.

This study investigates whether variability in perceived trait judgements disrupts our ability to match unfamiliar faces. In this preregistered study, 174 participants completed a face matching task where they were asked to indicate whether two ambient face images belonged to the same person or different people (17,748 total data points). Participants completed 51 match trials consisting of images of the same person that differed substantially on one trait (either trustworthiness, dominance or attractiveness) with minimal differences in the alternate traits. Participants also completed 51 mismatch trials which contained two photos of similar-looking individuals. We hypothesised that participants would make more errors on match trials when images differed in terms of attractiveness ratings than when they differed on trustworthiness or dominance. Contrary to expectations, images that differed in terms of attractiveness were matched most accurately, and there was no relationship between the extent of differences in attractiveness ratings and accuracy. There was some evidence that differences in perceived dominance and, to a lesser extent, trustworthiness were associated with lower face matching performance. However, these relationships were not significant when alternate traits were accounted for. The findings of our study suggest that face matching performance is largely robust against variation in trait judgements.

Within-Person Variability in First Impressions From Faces.

Perceptions of an individual can change dramatically across different images of their face. Questions remain as to whether some traits are more sensitive to image variability than others. To investigate this issue, we constructed a database of 340 naturalistic images consisting of 20 photos of 17 individuals. In this preregistered study, 95 participants rated all 340 images on one of three traits: trustworthiness, dominance, or attractiveness. Across images, participants' trustworthiness ratings tended to vary more than dominance, which in turn varied more than attractiveness; however, the relative differences between traits depended on the identity in question. Importantly, despite the variability in ratings within identities, there were substantial differences between individuals, suggesting that these trait judgements are based to some degree on relatively invariant facial characteristics. We found greater between-identity variability for attractiveness judgements compared to trustworthiness and dominance. Future research should further investigate the extent to which each trait dimension is tied to the identity of the faces.

Knowledge of identity reduces variability in trait judgements across face images.

Faces vary from image to image, eliciting different judgements of traits and often different judgements of identity. Knowledge that two face images belong to the same person facilitates the processing of identity information across images, but it is unclear if this also applies to trait judgements. In this preregistered study, participants (N = 100) rated the same 340 face images on perceived trustworthiness, dominance, or attractiveness presented in randomised order and again later presented in sets consisting of the same identity. We also explored the role of implicit person theory beliefs in the variability of social judgements across images. We found that judgements of trustworthiness varied less when images were presented in sets consisting of the same identity than in randomised order and were more consistent for images presented later in a set than those presented earlier. However, knowledge of identity had little effect on perceptions of dominance and attractiveness. Finally, implicit person theory beliefs were not associated with variability in social judgements and did not account for effects of knowledge of identity. Our findings suggest that knowledge of identity and perceptual familiarity stabilises judgements of trustworthiness, but not perceptions of dominance and attractiveness.