Written by Dr Natalie Butcher, Senior Lecturer in Psychology at Teesside University, Centre for Applied Psychological Science, Cognition and Decision-Making theme. Email: n.butcher@tees.ac.uk
During the COVID-19 pandemic, most countries and health organisations (e.g. the WHO) have recommended wearing face masks to reduce the spread of the severe respiratory syndrome 2 (SARS 2) coronavirus. In fact, many governments have now made it a requirement that citizens wear a face mask in particular settings. This has meant that the face mask, a previously mundane object, has been put in the spotlight across the globe, at the forefront of media and public discourse for almost a year. During this time, as someone who studies face recognition, I have frequently been asked by friends and colleagues, variants of the same question… “does wearing a mask effect face processing and recognition?”.
My response to this question has always been that I expect so. Until recently there was little research on the specific effect wearing a face mask has on face recognition, but what we already knew about face processing strongly suggested to me that wearing a face mask would interrupt normal face processing and lead to more face recognition errors in our daily lives. Indeed, I can think of several occasions over the last 12 months when it has taken me longer to recognise a mask wearing friend out for their daily exercise or I have awkwardly completely unrecognised a masked friend whilst grocery shopping. Decades of research has told us that we process faces holistically – this means that we process faces as a whole, not as individual features (for a review see Richler & Gauthier, 2014). Wearing a face mask covers a significant amount of the face and facial features (i.e. nose and mouth) meaning that the holistic memory we have of the person’s whole face doesn’t match what we see, making it harder to recognise the person or perceive what emotion they are expressing.
A growing body of literature has begun to emerge that has sought to answer the question more directly both in terms of face identification (i.e. who the person is) and expression recognition (i.e. what emotion is that person displaying). So, does wearing a face mask effect face and expression recognition?
Face Identification
Prior to the Covid-19 pandemic, research was conducted to understand what impact disguises have on face identification. One study used various disguises (e.g. hats, glasses, wigs, beards) including a disposable doctor’s mask and found participants were impaired in recognition of masked faces (Dhamecha et al., 2014). Since the pandemic began researchers have focussed on face masks more specifically. Carragher and Hancock (2020) investigated whether surgical face masks affect performance on a face matching task. Participants were shown pairs of facial photographs in several conditions: control (no masks), mixed (one face wearing a mask) and masked (both faces wearing a mask). They were asked to judge whether the two faces in each pair showed the same person or two different people. What they found will not come as a surprise – surgical face masks had a large negative effect on face matching even when participants saw familiar faces rather than unfamiliar. When matching masked faces, people were more likely to reject unfamiliar faces as “mismatches” and to accept familiar faces as “matches”. The findings of Freud et al. (2020) have since supported these findings. Their 496 participants completed one of two versions (masked or original) of the Cambridge Face Memory Task, a validated measure of human face recognition ability. Participants who completed the masked version performed substantially worse than those who saw unmasked faces and their findings suggest that holistic processing, the hallmark of face perception, was disrupted by mask wearing. In sum, the research published to date shows that yes wearing a face mask does make it harder to recognise each other, but does it also make it harder to recognise facial expressions?
Expression Recognition
Whilst processing the whole face is considered a hallmark of face recognition, some research has suggested that the eyes, which are still in view when wearing a face mask, are a particularly important feature when trying to discern someone’s facial expression. Just last year Schmidtmann et al. (2020) found that participants can recognise subtle differences between facial expressions based on the eye region only, even when the face is observed for a very brief time. But how do people perform on masked expression recognition tasks compared to unmasked faces? Initial findings from Carbon (2020) suggested that emotional expression recognition might be similarly negatively affected by wearing a face mask. Participants saw faces displaying one of six different emotional expressions (anger, disgust, fear, happy, neutral, and sad) while being fully visible or wearing a face mask and had to decide which expression each face was showing. Not only were participants less confident when presented with mask wearing faces, they were also less accurate. Face masks led to confusion between emotional expressions with participants confusing disgusted faces as being angry and happy, sad and angry faces as neutral. However, Calbi et al. (2021) found quite the opposite. Their participants similarly saw facial expressions (angry, happy and neutral) covered by a sanitary mask or by a scarf and were asked to evaluate what emotion was being expressed, but their results differed. Despite the mask covering the lower-face, participants were able to correctly recognise these facial expressions of emotions. So, the jury is still out on what impact wearing a face mask has on expression recognition as the research published so far has shown mixed results.
It’s clear that wearing a face mask has broader implications than it’s intended use of reducing the spread of coronavirus, not least for social interaction. It’s also important that we bear in mind that the discussed negative consequences to face identification when a person is wearing a mask could have serious implications when it comes to eyewitness identifications, with Carragher and Hancock (2020) suggesting that eyewitness identification decisions for masked faces should be treated with caution.
References
Carbon, C-C. (2020). Wearing Face Masks Strongly Confuses Counterparts in Reading Emotions. Frontiers in Psychology, 25;11:566886. doi: 10.3389/fpsyg.2020.566886.
Calbi, M., Langiulli, N., Ferroni, F., Montalti, M., Kolesnikov, A., Gallesse, V., & Umilta, M. A . (2021). The consequences of COVID-19 on social interactions: an online study on face covering. Scientific Reports, 11, 2601. https://doi.org/10.1038/s41598-021-81780-w.
Carragher, D.J., Hancock, P.J.B. (2020). Surgical face masks impair human face matching performance for familiar and unfamiliar faces. Cognitive Research: Principles and Implications, 5(59). https://doi.org/10.1186/s41235-020-00258-x
Dhamecha, T. I., Singh, R., Vatsa, M. & Kumar, A. (2014). Recognizing disguised faces: Human and machine evaluation. PLoS ONE 9, e99212.
Freud, E., Stajduhar, A., Rosenbaum, R.S, Avidan, G., & Ganel, T. (2020). The COVID-19 pandemic masks the way people perceive faces. Scientific Reports, 10, 22344. https://doi.org/10.1038/s41598-020-78986-9
Richler, J. J., & Gauthier, I. (2014). A meta-analysis and review of holistic face processing. Psychological Bulletin, 140, 1281–1302. doi: 10.1037/a0037004
Schmidtmann, G., Logan, A. J., Carbon, C-C., Loong, J. T., & Gold, I. (2020). In the Blink of an Eye: Reading Mental States From Briefly Presented Eye Regions. i-Perception. doi:10.1177/2041669520961116