Unattractive faces are more attractive when the bottom-half is masked, an effect that reverses when the top-half is concealed

Pazhoohi, Farid; Kingstone, Alan

doi:10.1186/s41235-022-00359-9

Original article
Open Access
Published: 24 January 2022

Unattractive faces are more attractive when the bottom-half is masked, an effect that reverses when the top-half is concealed

Farid Pazhoohi¹ &
Alan Kingstone¹

Cognitive Research: Principles and Implications volume 7, Article number: 6 (2022) Cite this article

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Abstract

Facial attractiveness in humans signals an individual’s genetic condition, underlying physiology and health status, serving as a cue to one’s mate value. The practice of wearing face masks for prevention of transmission of airborne infections may disrupt one’s ability to evaluate facial attractiveness, and with it, cues to an individual's health and genetic condition. The current research investigated the effect of face masks on the perception of face attractiveness. Across four studies, we tested if below- and above-average attractive full faces are equally affected by wearing facial masks. The results reveal that for young faces (Study 1) and old faces (Study 2) a facial mask increases the perceived attractiveness of relatively unattractive faces, but there is no effect of wearing a face mask for highly attractive faces. Study 3 shows that the same pattern of ratings emerged when the bottom-half of the faces are cropped rather than masked, indicating that the effect is not mask-specific. Our final Study 4, in which information from only the lower half of the faces was made available, showed that contrary to our previous findings, highly attractive half-faces are perceived to be less attractive than their full-face counterpart; but there is no such effect for the less attractive faces. This demonstrates the importance of the eye-region in the perception of attractiveness, especially for highly attractive faces. Collectively these findings suggest that a positivity-bias enhances the perception of unattractive faces when only the upper face is visible, a finding that may not extend to attractive faces because of the perceptual weight placed on their eye-region.

Significance statement

Wearing face masks are generally used in healthcare settings by health professionals to prevent transmission of diseases. However, currently wearing of face-masks has extended globally to the general population to reduce the transmission of COVID-19. The practice of face masks on a daily basis can impair one's ability to perceive faces, and may affect perceptions of facial attractiveness. In the current research we investigated the effect of facial masks on the perceptions of facial attractiveness. Our results show that wearing face masks increase the perceived attractiveness of less attractive faces in both young and old people, while face masks do not affect highly attractive faces.

Introduction

Facial attractiveness in humans is an honest signal of an individual’s genetic condition, underlying physiology and health status, and thus serves as a cue of one’s value as a potential mate (Thornhill & Gangestad, 1999). Importantly, humans have evolved psychological mechanisms to distinguish and discriminate facial features about such qualities (Little et al., 2011; Thornhill & Gangestad, 1999). For instance, men and women prefer symmetrical faces in the opposite sex as it also is able to signal genetic quality and healthy development (Grammer & Thornhill, 1994; Rhodes, 2006; Thornhill & Gangestad, 1993). Similarly, people prefer average faces, possibly because they signal genetic heterozygosity and resistance to disease (Grammer & Thornhill, 1994; Rhodes et al., 2001). Men and women also prefer sexually dimorphic faces in the opposite sex (i.e., feminine traits in female faces and masculine traits in male faces), as such features may be viewed as denoting genetic condition, hormonal profile, health and immunity (Little et al., 2011; Rhodes, 2006; Thornhill & Gangestad, 1999, 2006). Faces can also convey other information regarding one’s health, genetic condition and mate value, including skin health and color, adiposity and weight (De Jager et al., 2018; Little et al., 2011; Stephen et al., 2011).

Humans, as a social animal, may adhere to practices that cover some parts of the face. For example, some Muslim women may cover their faces by wearing face covering veils such as the niqab, which impairs facial expression recognition by observers (Fischer et al., 2012; Kret & De Gelder, 2012); it may also serve the intended purpose of decreasing women’s attractiveness by their male relatives (Pazhoohi, 2016; Pazhoohi & Kingstone, 2020). Another practice is wearing surgical masks (or simply face masks) in healthcare settings by health professionals to prevent transmission of airborne infections, and is presently practiced globally by the general population to reduce the transmission of COVID-19. Yet face masks also impair one's ability to perceive faces and the emotions that they convey (Carbon, 2020; Freud et al., 2020; Pazhoohi et al., 2021). It thus follows that the facial covering practices may impair one's ability to perceive signals of health and genetic condition, and hence, the attractiveness of others.

To the best of our knowledge, save for a study by Miyazaki and Kawahara (2016), no research has examined the effect of facial masks on the perception of attractiveness prior to COVID-19 pandemic. Miyazaki and Kawahara used a facial mask, as well as a notebook or a card, to occlude the lower part of faces and found that the facial mask reduced perceived attractiveness, while the other occluding objects increased it, suggesting that both factors can impact judgements of attractiveness. A facial mask may prime unhealthiness, reducing perceived attractiveness; whereas occluding the face by objects, other than face mask, may tap into a face-specific positivity bias. This latter interpretation is supported by a recent study by Orghian and Hidalgo (2020) who reported that photos of incomplete faces are perceived as more attractive, although we hasten to add that this study did not consider occlusion of the bottom half of the face, but rather manipulations to photos of faces such as blurring, cropping two-thirds of an entire face, and randomly removing pixel images.

The present study sought to extend these novel results with a closer inspection of the effect of a face mask on the perception of facial attractiveness, by comparing masked faces to when the bottom- or top-half of the faces are cropped. In doing so we can test whether the results found using a Japanese sample by Miyazaki and Kawahara (2016) extend to another culture; specifically, their finding that unlike occlusion which increased perceived attractiveness, only face masks reduce the perceived attractiveness of high (and average female) faces, but not low attractive faces. A similar outcome would suggest that the pattern reported by Miyazaki and Kawahara (2016), is a general phenomenon, and not a culturally-specific one. Failure to replicate their findings would exclude this possibility. For instance, in keeping with the positivity bias suggested by Orghian and Hidalgo (2020), we might find that masks increase the perception of attractiveness. An alternative possibility is that masks will interfere with the perception of features that are both attractive (e.g., symmetry) and unattractive (e.g., asymmetry) the result being that attractive faces when masked may be perceived as less attractive but unattractive faces when masked may appear more attractive.

Study 1

In the first study, we tested the effect of a facial mask on perception of attractiveness using a sample of young people's faces with a neutral facial expression.

Method

Participants

A total of 164 individuals (58 men and 106 women), aging between 18 and 75 years of age (M = 40.6, SD = 14.3), were recruited from TurkPrime panel as participants. A total of 92 participants (56.1%) reported being married, 1.2% reported widowed and an additional 8.5% reported being divorced or separated, while 24.4% reported being single, and 9.8% in a relationship. In terms of their highest educational degree, 30.5% had a high school diploma, 7.3% had a post-secondary diploma, 25.0% of the participants had an undergraduate degree, one reported elementary school and 36.6% had a post-graduate degree.

Stimuli and procedure

Images of 25 male and 25 female faces, aged between 19 and 31 years and with a neutral expression, were obtained from the FACES database (Ebner et al., 2010), resulting in 50 stimuli. Another set of 50 stimuli of the same identities were created by superimposing a facial mask on the original images. Each set of stimuli (masked or unmasked) were randomised and presented in separate blocks. After consenting to participate in the study, participants answered sociodemographic questions. A within-subjects design was used, and participants randomly observed either the block with facial masks first or the block without masks first. Participants were asked to respond to the question “How attractive do you find this man?” or “How attractive do you find this woman?” on a 7-point scale, from 1 (not at all) to 7 (very) (Fig. 1).

Data analysis

The average ratings of attractiveness for the original unmasked stimuli was calculated and the stimuli were grouped as above (high attractiveness) and below (low attractiveness) the average. All post hoc comparisons throughout the results of this and next studies were performed using Bonferroni correction, and this is reflected in the p values. A G*Power analysis for a 2 × 2 × 2 × 2 mixed effects design indicated that 92 participants would be sufficient to detect a small effect size (f = 0.10, β = 0.80). In our studies we recruited participants almost twice the needed size (~ 180).

Results

A linear mixed model was conducted to investigate the effect of presence/absence of facial mask, stimuli sex, participants’ sex, and attractiveness group (low and high) on the ratings of attractiveness in young people faces, with participants as a random factor. Results showed significant main effects for facial mask, stimuli sex, participant sex, and attractiveness group (see Additional file 1: Table S1 for details). The main effect of mask was further qualified by two 2-way interactions: Mask × Attractiveness Group, and Mask × Stimuli Sex.

The Mask × Attractiveness Group interaction showed that for the low attractiveness group, participants rated faces with masks (M = 4.28, SEM = 0.11) as more attractive compared to their unmasked faces (M = 3.97, SEM = 0.11, p < 0.001); while in the high attractiveness group the ratings were not significantly different between masked (M = 4.57, SEM = 0.12) and unmasked of attractive faces (M = 4.52, SEM = 0.12, p = 0.999) (Fig. 2, left panel).

The Mask × Stimuli Sex interaction (as seen in Fig. 2, right panel) reflects that as females are more attractive than males overall (ps < 0.012) and masks increase the attractiveness of both females and males (ps < 0.001), a masked male (M = 4.30, SEM = 0.12) is perceived as attractive as an unmasked female (M = 4.31, SEM = 0.11, p = 0.999), but a masked female (M = 4.55, SEM = 0.11) is significantly more attractive than an unmasked male (M = 4.18, SEM = 0.12, p < 0.001).

Discussion

Results of the first study showed that facial masks increased ratings of attractiveness for those faces that were less attractive than average, while having no effect on above average attractive faces. Such results are in contrast with those of Miyazaki and Kawahara (2016), who reported an overall negative effect of facial masks on ratings of attractiveness. However, our results converge partially with those of Orghian and Hidalgo (2020) who showed a positive bias for incomplete faces. Nonetheless, our result is limited to a sample of young faces and might not be generalized to a broader population (i.e., older adults).

Previous research has shown that individuals consider younger faces more attractive than older faces (Ebner, 2008; Kwart et al., 2012). It is suggested that age-related features in older faces such as lines, wrinkles, and furrows on skin results in their being perceived as relatively less attractive than younger faces (Berry & McArthur, 1986; Matts et al., 2007).

To the extent that our finding in Study 1 is robust, we would expect masks to increase the attractiveness only of older adult faces that are less attractive on average. Alternatively, because older adults are generally less attractive than younger faces, one might expect that masks will increase the attractiveness rating of all older faces. There is a second reason to expect this outcome. By covering the lower part of the face, wearing facial masks would reduce the evidence of age-related changes to the face, thereby making all of the older faces more attractive.

Study 2

In the second study we aimed to extend the results found for young faces to old people faces and test whether the effect from Study 1 holds true when using face stimuli with a different age range.