Surprise is a reaction to suddenly perceiving something unexpected. Emotional reactions to sudden and unexpected events are named according to their intensity. Mildly sudden and unexpected events cause surprise, moderately sudden and unexpected events cause astonishment, and extremely sudden and unexpected events cause shock.

Surprise – Astonishment – Shock

The eyes and mouth open in coordination with each other, a fluid motion that raises the eyebrows and opens the mouth moderately. These motions are read instinctively by observers as an impression that something new has been realised. The heart rate increases a few beats a minute, and a little gasp of air is drawn and then held to aid hearing. These prepare the body in the mildest of fashions to move away if needed. This is an observably common emotion and its features can be witnessed in many animals.1
All the expressions are mild; the event is not seriously alarming in nature. The little gasp of air that’s inhaled hardly inflates the lungs or increases posture. The breath is held to aid hearing and then released with a barely perceptible sound or quite frequently as a sigh of relief or chuckle. These are all soft moderate expressions.

The reaction itself is neutral and preparatory in nature. The sudden and unexpected perception instinctively causes the mind to wonder what is happening, so that the situation is assessed immediately. If the experience is perceived as positive, the expression morphs into amusement. If the experience is perceived as negative, the expression morphs into that of being scared, or relief when the scary thought is assessed as untrue. These processes would normally happen in milliseconds or seconds, and other emotions may be felt as a result of the appraisal. After the initial assessment, gladness or sadness may be felt at the same time as feeling amused or scared. Yet the wonder of people’s surprise may not be completely satisfied and may continue to reappraise the situation if no solid conviction is reached. In these cases people would feel the amusement or scare of the situation taking up part of their conscious thought while they continue to feel other emotions at the same time.


Latin. Prehendere = to grasp, seize, something unexpected.

1. To encounter suddenly or unexpectedly; take or catch unawares.

2. To attack or capture suddenly and without warning.