I’d like to discuss some difficult emotions such as guilt, shame, and embarrassment. These emotions do not have unique facial expressions.
Guilt and shame are hard to distinguish from sadness, except for the possibility that the head may be turned away. The failure to have a distinctive signal for guilt and shame, however, makes sense, since when feeling these emotions the person does not want others to know how he or she feels, and so perhaps a signal did not evolve.Embarrassment is more problematic.
The blush doesn’t qualify as an embarrassment signal because it is not observable in everyone. Dacher Keltner has shown that there is not a single momentary expression for embarrassment, as there is for anger, fear, disgust, contempt, sadness, and enjoyment.Read more on paulekman.com