Israeli Researchers Evaluate How Masks Disrupt Facial Perception in New Study

If a man wearing a mask had come into the bank where you worked a year ago, you would probably be horrified and think he was a robber insisting that you hand over the cash. Today, as people around the world wear surgical and cloth masks to protect themselves and others from the COVID-19 virus, the connotation of face covers has changed completely. And even as people get vaccinated in large numbers, we will continue to wear them for at least several months until herd immunity develops. 

 

Faces are among the most informative and significant visual stimuli in human perception. Brief presentation of a person’s face readily exposes their identity, gender, emotion, age, and race. Previous studies have shown that the recognition of facial expressions is altered if the lower part of the face is occluded by a scarf or ethnic related headdresses.

Photo Caption: Photos reproduced with permission from the Chicago Face Database

The unprecedented efforts to minimize the effects of the COVID-19 pandemic introduce a new arena for human face recognition in which faces are partially occluded with masks. Given the importance of intact face processing to everyday life and to social interactions, it is imperative to characterize how wearing masks might hamper these abilities.

The identification of people wearing masks has presented a unique challenge during the pandemic. A new study by researchers from Ben-Gurion University (BGU) of the Negev in Beersheba and York University in Canada reveals the impact of this predicament and its potentially significant repercussions. 

 

Their findings were just published in the journal Scientific Reports under the title “The COVID-19 pandemic masks the way people perceive faces.” 

 “For those of you who don’t always recognize a friend or acquaintance wearing a mask, you are not alone,” wrote Prof. Tzvi Ganel, head of the Laboratory for Visual Perception and Action at BGU’s psychology department and Prof. Erez Freud, who earned his doctoral degree at BGU and is now a faculty member at York University in Toronto. 

“Faces are among the most informative and significant visual stimuli in human perception and play a unique role in communicative, social daily interactions,” the researchers noted. “The unprecedented effort to minimize COVID-19 transmission has created a new dimension in facial recognition due to mask wearing.” 

To examine the effects of wearing masks, Ganel and Freud used a modified version of the Cambridge Face Memory Test (CMFT) – the standard for assessing facial perception, which included masked and unmasked faces. A total of nearly participants (151 of them women) with a mean age of 25.5 years were recruited online between May and June 2020 (two or three months after mask wearing became common). They participated in two experiments and were compensated for their time. 

Participants were randomly assigned to one of two groups. The first group completed the original CFMT (faces without masks), while the second group completed a modified version of the CFMT in which an identical face mask was added to all faces. The researchers found that the success rate of identifying someone wearing a mask was reduced by 15%. 

“This could lead to many errors in correctly recognizing people we know, or alternatively, accidently recognizing faces of unfamiliar people as people we know,” commented Prof. Galia Avidan of BGU’s psychology department and department of Cognitive and Brain Sciences who is an expert on facial recognition and perception. “Face masks could be even more challenging to people whose face recognition skills are not ideal to begin with and cause greater impairment,” said Avidan.

 The research team also found that masks specifically interfered with extracting a holistic impression of faces and led to feature-by-feature processing which is a less accurate and more time-consuming strategy. “Instead of looking at the entire face, we’re now forced to look at the eyes, nose, cheeks and other visible elements separately to construct an entire facial face percept – which we used to do instantly,” the researchers wrote. 

These performance changes, along with the alteration along the processing style of faces, could have significant effects on activities of daily living, including social interactions, as well as other situations involving personal interactions, such as education. “Given that mask wearing has rapidly become an important norm in countries around the globe, future research should explore the social and psychological implications of wearing masks on human behavior,” Ganel said. “The magnitude of the effect of masks that we report in the current study is probably an underestimation of the actual degree in performance 

Face masks are an important tool in the effort to minimize COVID-19 virus transmission and, as a result, are increasingly prominent in everyday social interactions. Here, we evaluated the extent to which face masks lead to a decrease in face perception abilities. We have documented quantitative and qualitative alterations in face processing abilities for masked faces. In Experiment 1, we found that the face masks led to a robust decrease in face processing abilities measured by the well-established CFMT. This quantitative reduction was accompanied by a weaker inversion effect, suggesting that the processing of masked faces is less holistic.

The BGU-led study “provides novel evidence for quantitative and qualitative changes in the processing of masked faces. These changes in performance, together with the alteration along the processing style of partially occluded faces, could have significant effects on activities of daily living, including social interactions, as well as other situations involving personal interactions such as education,” the researchers wrote.  

“Previous research already indicated that reduced face perception abilities following age-related macular degeneration is accompanied by negative consequences of social disengagement, a decrease in the level of social confidence, and a general decrease in quality of life. Given that wearing masks has rapidly become an important norm in countries around the globe, future research should explore the social and psychological implications of this behavior,” they concluded.


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