Governor Mike Pence and Senator Tim Kaine faced off tonight in their only Vice Presidential debate of this Campaign cycle.
You may have noticed that Tim Kaine's left eyebrow and left forehead muscles were elevated significantly more (in both frequency and amplitude) versus his right side. If we only had seen a short video sample or some still images we may conclude that this was a nonverbal signal of Kaine's disbelief regarding some of Pence's (or Trump's) statements, opinions or actions. And while there's no doubt that Hillary Clinton's running mate certainly felt such incredulity - the majority of the time this was not cause for this particular facial configuration.
What, then were we seeing?
Senator Kaine has a partial facial nerve palsy on his right side (probably congenital or from trauma early in life). This gives the (false) appearance of over-action of his left forehead. The facial nerve (Cranial Nerve VII) innervates (among other things) the muscles on each side of the face (there's one for the left side and one which innervates the muscles on the right). As with most all medial problems there's a list of possible etiologies (trauma, asymmetrical Botox reaction, congenital, tumor, lyme disease, etc.) and if all other causes are ruled out, this condition would then properly be termed "Bell's Palsy" (a diagnosis of exclusion). Tim Kaine's partial facial nerve palsy thus makes it erroneously appear (at least some of the time) that he's incredulous.
Of course, such a condition does not prevent Kaine from thinking-feeling disbelief, but it does make us more likely to misinterpret him - AND thus, importantly, also makes him less likable. This is one occasion where Botox should indeed be used to partially mute the action of his left forehead - thereby enabling his facial expressions to take on a more symmetrical, friendly - and accurate appearance.
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