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I don't know but maybe. Maybe an academic or safety regulator has a study somewhere. It feels a bit like you might start indicating to trigger the camera and check your blind spot which is a bit frightening to anyone that is in that spot at that time (which they shouldn't linger in etc).
On the other hand perhaps it increases the chances of people indicating which some drivers seem to think is unnecessary.
Surely it's safer as it doesn't require you to remove your eyes from looking in the direction of travel and isn't encumbered by the b pillar.