structural:summarization
Non-verbal responses

Surprise is expressed in the face by the following features:

Spontaneous, involuntary surprise is often expressed for only a fraction of a second. It may be followed immediately by the emotion of fear, joy or confusion. The intensity of the surprise is associated with how much the jaw drops, but the mouth may not open at all in some cases. The raising of the eyebrows, at least momentarily, is the most distinctive and predictable sign of surprise.

Despite the facial feedback hypothesis (that facial display is necessary in the experience of emotion or a major determinant of feelings), in the case of surprise, some research has shown a strong lack of connection between the facial display of surprise and the actual experience of surprise. This suggests that there are variations in the expression of surprise. It has been suggested that surprise is an envelope term for both the startle response and also disbelief. More recent research shows that raising of the eyebrows does provide facial feedback to disbelief but not to the startle.

Pupil dilation and constriction can determine the valence of surprise from the action to the reaction of the individual. Positive valence to surprise is shown through a dilation or expansion of the pupil, where as negative valence in surprise is associated with pupil constriction. But, newer studies show pupil dilation for negative as well as positive stimuli, indicating a general autonomous arousal associated with pupil dilation and not affective valence.

Non-verbal responses to surprise can also be affected by voice inflection, distance, time, environment, volume, rate, quality, pitch, speaking style, and even the level of eye contact made by an individual trying to cause a surprise. These non-verbal cues help to define whether the perceived surprise will have a positive or negative valence and to what degree the surprise will be induced by the individual.