Been thinking about personal space given recommendations for increasing it to 2 meters -- and this paper by @AleAliSousa and others came to mind: How do we perceive interpersonal distance if there is a glass barrier? frontiersin.org/articles/10.33… Of course if it were not transparent, you might not even know someone is there unless the barrier is small and you can detect them with another sense. But the distance we are comfortable with does seem like it should be somewhat smaller with a barrier -- maybe not face-to-face!