A new study by scientists at USC and California State University, Northridge, reveals that face masks — while important to public health and recommended in many health care settings — can make it harder for people of all ages to recognize emotions when faces are covered.

The research, published in the journal Emotion, found that expressions of sadness were the most difficult to identify for all age groups. Parents reporting high levels of stress and symptoms of depression had to use even more brain power to decode sad emotions behind masks, suggesting stress amplifies these challenges.

Using MRI brain scans, the researchers analyzed brain activity in fathers and their children. They measured the increased effort required to interpret facial expressions and identified the specific brain areas involved in processing emotional cues.

“Masks obscure the key emotional cues that human interaction relies on, making it harder to connect and communicate in the ways we’re accustomed to and requiring us to adapt how we read and respond to others,” said Yael Waizman, a doctoral student in the Department of Psychology at the USC Dornsife College of Letters, Arts and Sciences and the study’s corresponding author.

“For kids, it’s especially important to be mindful of their emotional cues when they’re wearing face masks, as children learn by observing and modeling behaviors,” she said. “This can be particularly challenging for stressed fathers, who may need extra support in helping their children recognize and express emotions effectively.”

Heightened brain activity required to decode masked faces

The study included three racially and ethnically diverse samples. The researchers first recruited families participating in a larger longitudinal study being conducted at the NeuroEndocrinology of Social Ties (NEST) Lab at USC Dornsife. From that group, they selected a sample of 30 children who started school at the beginning of the COVID-19 pandemic, along with 31 fathers of those children. The researchers also recruited 119 undergraduate students via Cal State Northridge’s research management system.

“Fathers make key contributions to parenting, and understanding how they process emotion can tell us more about how they might model empathy for their kids,” said senior author Darby Saxbe, a professor of psychology at USC Dornsife and principal investigator of the NEST Lab.

Participants were shown images of adults and children, both with and without masks, and asked to identify emotions such as sadness, fear or anger based on the facial expressions.

The larger USC study involved one family lab visit and two MRI visits — one for fathers and one for children. Of those, 41 participants (23 fathers and 18 children) took part in a task while having a brain scan, while the remaining 20 participants (eight fathers and 12 children) who were not eligible for scans took part in the task during their lab visit, but without the MRIs. After the lab visits, fathers filled out online surveys about their background and mental health. All 119 college students completed the facial recognition task virtually.

The results showed that masked faces were harder to recognize, both behaviorally and in brain activation patterns, for all age groups. Faces expressing sadness were especially difficult to identify.

“When responding to masked faces, we observed increased activity in brain regions associated with decoding facial expressions, emotion recognition and social cognition compared to unmasked faces,” said Waizman, who works in Saxbe’s NEST Lab.

“Sad faces, in particular, required more brain resources to interpret, with heightened activation in areas like the frontal-parietal gyri and the insula — regions critical for understanding and processing others’ emotions,” she added.

Waizman added that because sadness often prompts us to seek support and connection, it’s crucial to ensure that masks don’t interfere with those meaningful interactions.

Stressed parents face added difficulty

The study also found that fathers reporting higher levels of stress or depressive symptoms had to use more brain resources to recognize sad faces behind masks. These parents showed increased brain activity in regions associated with emotion recognition, indicating that stress may make it more difficult to process emotional cues.

“We know that stress can affect our ability to empathize with others, which is an important part of parenting,” Saxbe said. “Managing stress can help us read each other’s emotions better.”

Adapting to masked communication

“Masks are essential in many settings, including health care, schools and public spaces, to protect public health, but they also complicate how we connect with others,” Waizman said. “This raises important questions about how we can offer the support people need when the emotional cues we depend on are concealed.”

Waizman added that because sadness often prompts us to seek support and connection, it’s crucial to ensure that masks don’t interfere with those meaningful interactions.

“By raising awareness and encouraging attentiveness to other cues, we can protect our social-emotional connections while maintaining the safety masks provide,” she said.

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About the study: Co-authors include Sara R. Berzenski of California State University, Northridge’s College of Social and Behavioral Sciences; Anthony G. Vaccaro, Phillip Newsome, Elizabeth C. Aviv and Gabriel A. León from the Department of Psychology at USC Dornsife. The study was supported by the National Institutes of Health (R01-HD104801).