Ten-month-old babies and toddlers who grew up during the coronavirus crisis were unable to distinguish between frightened and happy faces, research by Utrecht University has shown.

The researchers wanted to find out if the social restrictions during the pandemic, such as mask wearing and lockdown, influenced the early neurological development of babies.

“It’s the age when babies learn much from facial expressions,” researcher Carlijn van den Boomen said. “They learn to distinguish and interpret emotion.”

The research measured the responses of 473 children aged five months, 10 months, and three years. A scanner registered the brain activity prompted by different facial expressions they were shown.

The researchers had already done the same with a group of 462 children before the outbreak of the virus as part of another, long term research project into child development.

The researchers found the children who grew up during the pandemic were unable to distinguish between a frightened and a happy face. Happy faces were particularly difficult to process, Van Boomen said.

The researchers said that mask-wearing and a lack of social intercourse may have contributed to the lack of response. Van den Boomen said the research shows the importance of babies seeing different people in different situations.

The results are important not just for parents but for policymakers, Van den Boomen said. “There are so many children involved. Parents and politicians must be made aware of what the effects of such policies are,”  she said.

The researchers did not investigate whether the children recovered their ability to distinguish facial expressions after the pandemic. “We discovered from earlier research that babies whose development stagnated during the pandemic caught up later. We hope the same will happen here,” she said.

But even if that is the case, long-term effects can’t be discarded, Van den Boomen said. “Recognising emotions is essential for a child’s social development and learning. It may be that their development during the pandemic stalled in other respects as well,” she said.