Again when I recognise my daughter's voice on the telephone a brief smile indicates the affect Enjoyment-Joy before a negative affect is triggered by her obvious distress. Enjoyment-Joy is always produced by a reduction in brain activity, in the rate of neural firing. Such reduction in brain activity will produce a smile with the lips widened up and out. A level of calm and contentment will ensue. Any stimulus that produces a reduction in high-level activity will produce a smiling face.
Surprise has urgency and implies instant action.
The main purpose of surprise-startle is to clear away any other affects, responses and ongoing activity in order to concentrate upon the cause of the affect itself. Surprise-Startle is the briefest Affect. It arrives and is gone in a fraction of the second. The facial expression is eyebrows up, eyes wide open, blink and mouth open. Depending on earlier experiences and memories it may be personally perceived as a positive or negative affect, evoking a positive or negative response.