Conjoined twins Anias (left) and Jadon McDonald were successfully separated after a 27 hour surgery about 6 weeks ago. Thankfully they are making a record recovery. And although in the past, they could see each other in a mirror or via photographs (and even each others hands) - the image above captures the moment when, after their surgery, they first looked at each other directly.
(Empathy-test side bar: You should be in tears right now)
From a nonverbal perspective, many would confuse Jadon's and Anias' expression with that of surprise, it's not - rather it is that of emotional shock/emotional processing.
Note both Jadon's and Anias' mouths - each is partially open, but not widely so. The mouth of true surprise is opened wider - in a vertically-oriented oval shape (but also show no teeth). The mouth of emotional shock/emotional processing is characterized by relaxed jaw muscles (temporalis, internal pterygoid and masseter) - which give rise to the colloquials - "Mouth Agape", "Drop Jawed" and "Slack Jawed". Although they are very young, and almost no one has lived through a similar experience, almost everyone can put themselves in their proverbial shoes. Their intellectual brains rare suddenly recognizing a profound new fact - yet their emotional brains have yet to come to terms with the new course of events ("I can't wrap my brain around it").
When comparing the facial expression of emotional processing/emotional shock to that of surprise - the eyes behave similarly to the mouth. For while with the former the eyes are certainly opened wider than baseline, they are not opened as wide as with sincere surprise. On the surface, this may appear to some to be a simple matter of degrees, it's not. Although their Venn diagrams overlap, Emotional Processing/Emotional Shock is a different emotion than that of surprise.
Another important distinction between these two feelings is that Emotional Shock/Emotional Processing is much longer-lived, while sincere surprise is the most short-lived of all emotions. True surprise will last only for a second or two - and importantly, will be rapidly replaced by another emotion (fear, anger, sadness, joy, etc.).
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