Abstract
The use of surgical-type face masks has become increasingly common during the COVID-19 pandemic. Recent findings suggest that it is harder to categorise the facial expressions of masked faces, than of unmasked faces. To date, studies of the effects of mask-wearing on emotion recognition have used categorisation paradigms: authors have presented facial expression stimuli and examined participants’ ability to attach the correct label (e.g., happiness, disgust). While the ability to categorise particular expressions is important, this approach overlooks the fact that expression intensity is also informative during social interaction. For example, when predicting an interactant’s future behaviour, it is useful to know whether they are slightly fearful or terrified, contented or very happy, slightly annoyed or angry. Moreover, because categorisation paradigms force observers to pick a single label to describe their percept, any additional dimensionality within observers’ interpretation is lost. In the present study, we adopted a complementary emotion-intensity rating paradigm to study the effects of mask-wearing on expression interpretation. In an online experiment with 120 participants (82 female), we investigated how the presence of face masks affects the perceived emotional profile of prototypical expressions of happiness, sadness, anger, fear, disgust, and surprise. For each of these facial expressions, we measured the perceived intensity of all six emotions. We found that the perceived intensity of intended emotions (i.e., the emotion that the actor intended to convey) was reduced by the presence of a mask for all expressions except for anger. Additionally, when viewing all expressions except surprise, masks increased the perceived intensity of non-intended emotions (i.e., emotions that the actor did not intend to convey). Intensity ratings were unaffected by presentation duration (500ms vs 3000ms), or attitudes towards mask wearing. These findings shed light on the ambiguity that arises when interpreting the facial expressions of masked faces.
Highlights
In 2020, many governments around the world introduced the mandatory wearing of face masks in public settings in an attempt to mitigate the spread of coronavirus (COVID-19)
It is possible that the incidence of mask-wearing will remain above pre-pandemic levels for many years to come, as people around the world seek to limit the transmission of new variants. In light of this dramatic change in our day-to-day behaviour, it is important to understand the implications of mask-wearing for non-verbal communication and social interaction
To ensure that participants had similar experiences of the COVID-19 pandemic and the associated use of face masks as a protective measure, participants were required to be currently resident in the UK, and to not have travelled abroad in the previous 12 months
Summary
In 2020, many governments around the world introduced the mandatory wearing of face masks in public settings in an attempt to mitigate the spread of coronavirus (COVID-19). It is possible that the incidence of mask-wearing will remain above pre-pandemic levels for many years to come, as people around the world seek to limit the transmission of new variants. In light of this dramatic change in our day-to-day behaviour, it is important to understand the implications of mask-wearing for non-verbal communication and social interaction. Facial expressions are a important form of non-verbal communication that can be used to infer someone’s emotional state and likely intentions [7,8,9]. Previous research suggests that human adults classify expressions of the socalled ‘basic emotions’ (happiness, sadness, anger, fear, disgust, surprise) with moderate-tohigh accuracy (ranging from around 60% to over 90%) after just 200ms of exposure to a face [10, 11]
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