Managers are right, back-to-back Zoom calls really are less useful than in-person meetings—and the latest scientific research backs this.

Usually, when people engage in a conversation their brains surge with neurological activity. Current research suggests that the same process should happen whether people are interacting in person or on Zoom.

But now, Yale University researchers have found that people’s faces are not able to light up people’s brains in the same way through a screen.

Engagement diminishes on Zoom

The study, published in the journal Imaging Neuroscience, meticulously recorded neural response signals of pairs speaking in person versus on Zoom, the popular video conferencing platform used by millions of white-collar workers daily.

Increased brain activity was observed during face-to-face interactions, including prolonged gaze time and greater pupil diameters, indicative of heightened engagement in both participants. However, brain activity was significantly reduced in comparison, when people were speaking on a video call.

“Zoom appears to be an impoverished social communication system relative to in-person conditions,” Joy Hirsch, a professor of comparative medicine and neuroscience, and lead author of the study said.

“Overall, the dynamic and natural social interactions that occur spontaneously during in-person interactions appear to be less apparent or absent during Zoom encounters.”

Live, face-to-face interactions are important for humans’ natural social behaviors and trump the online experience, Hirsch concluded—that is, for now at least.

“Online representations of faces, at least with current technology, do not have the same ‘privileged access’ to social neural circuitry in the brain that is typical of the real thing,” she added.

Previous research has echoed that Zoom stifles creativity. Columbia University researchers found that when workers brainstorm face-to-face, they produce more ideas and ideas that are more creative, compared with when on a video call.

Zoom declined to comment on the findings.

No wonder Zoom fatigue has been blamed for RTO calls

Despite workers saying that they can work effectively from home, leaders have been increasingly forcing their workers to give up remote working—and they’ve largely been blaming their return-to-work mandates on Zoom fatigue.

Earlier October, Roblox, the $19 billion gaming giant demanded staff work at the company’s physical office in California at least three days a week (which means relocation for some) or find another job, for that very reason.

Although its CEO and founder David Baszucki said that he was initially “impressed” with how staff took to working from home, it wasn’t long before he said he was dissuaded by the absence of learning, innovation, and company culture through a screen.

“For many of us, ‘Zoom fatigue’ is real,” he wrote in a memo to all staff. “A three-hour Group Review in person is much less exhausting than over video and brainstorming sessions are more fluid and creative.”

Even Zoom has Zoom fatigue. The company has asked its workers to come into the office at least two days a week because it provides an opportunity for workers “to interact with their teams.”

“The power of in-person collaboration will always be there,” Drew Smith, Zoom’s director of government relations for the U.K. & Ireland, previously told Fortune.