Surprise (emotion)
Physiological responses

The physiological response of surprise falls under the category of the startle response. The main function of surprise or the startle response is to interrupt an ongoing action and reorient attention to a new, possibly significant event. There is an automatic redirection of focus to the new stimuli and, for a brief moment, this causes tenseness in the muscles, especially the neck muscles. Studies show that this response happens extremely fast, with information (in this case a loud noise) reaching the pons within 3 to 8 ms and the full startle reflex occurring in less than two tenths of a second.

If the startle response is strongly elicited through surprise then it will bring on the fight-or-flight response, which is a perceived harmful event, attack, or threat to survival that causes a release of adrenaline for a boost of energy as a means to escape or fight. This response generally has a negative valence in terms of surprise.

Surprise has one core appraisal-appraising something as new and unexpected-but new appraisals can shift the experience of surprise to another. Appraising an event as new predicts surprise, but the appraisal of the coping mechanism predicts the response beyond surprise, such as confusion or interest.
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