Even when the internet gods are smiling on us, the quality of input information from a virtual meeting comes up short, says Philip Smith, who runs the Vision and Attention Laboratory at the University of Melbourne. "We're dealing with a speech signal that's degraded relative to face-to-face speech, even with a good internet connection, so the cognitive load required to process or decode it is greater." This signal includes visual as well as audio information. That's because we don't just listen with our ears; much of what we understand comes from what we see. And it turns out it's not so easy to read a virtual room. Watching a person from their shoulders up means you miss out on loads of body language. Plus if you've ever watched a movie or TV show where an actor's mouth and their speech are out of sync, you know just how off-putting lags can be. "In general, 100 milliseconds is the critical time period for us to experience things as synchronous or asynchronous," Professor Smith says. "So anything that occurs within about a 100-ms window is experienced as a unitary thing. "And if you separate things by much more than 100 ms, you start to experience them as different and separated." Such latency issues are commonplace with video calls, and require your brain to work just that little bit harder to match what it sees with what it hears.
Belinda Smith, 'Feel drained after a year of Zoom meetings? There's brain science behind that fatigue', ABC News