# Motivation and emotion/Book/2013/Surprise

Motivation and Emotion: Improve your life (2013) Emotion: Surprise

## What is the emotion of Surprise and what are its effects?

* Multimedia presentation (5 min)

## Overview: The Emotion of Surprise

The emotion of surprise consists of a sharp increase in neutral situation, typically brought about by a sudden or unexpected event. It is a brief mental and psychological state that is considered an adaptive, evolutionary-based reaction to unexpected events with both emotional and cognitive aspects (Franchin,Donati, Benelli, Stefanini, Zobec & Gregori, 2012). It is always a transient state, can have any valance; that is, it can be neutral/moderate, pleasant, or unpleasant; and serves the very useful function of clearing the nervous system of ongoing emotion and cognition (Franchin et al., 2012). By doing this, it allows the individual to respond appropriately to both the stimulus situation and the sudden change experienced before evolving in to another emotion (Perakyla & Sorjonen, 2012, p. 263).
A recent study by Vanderbilt University (2010) shows that the human senses become temporarily blind to certain information when genuinely surprised. The part of the brain that processes surprise is also linked to the part of the brain that allows the functionality of multi-tasking, focus, and attention to various stimuli (Christopher, Todd, Snyder & Marois, 2010). When experiencing a surprise state, the brain often turns off the multi stimuli and concentrates on what has caused this increase in the neutral situation, discrepancy, or source of the surprise (Christopher et. al, 2010), thus then allowing the information to be processed quickly in order to react accordingly.
Similarly to the other six universal expressions of emotion (sadness, anger, fear, disgust, joy and contempt), surprise has its own unique facial expression configuration. When someone is surprised, the eyebrows and upper eyelids tend to raise to enlarge the eye openings, the jaw drops, and the co-occurrence of these three changes in the face universally communicates that someone is typically experiencing surprise (Hastings, Tangney & Stuewig, 2008). Scientists believe that the reason for the raising of the eyebrows and the eyelids and the dropping of the jaw in surprise is to allow for the maximum intake of information in relation to the quick processing time. By allowing all of the senses to open, each universal emotion is able to be distinguished, as each has its own set of facial expression configurations, as well as its own function (Hastings et al., 2008). Even though surprise only shows itself very briefly, and can still vary in intensity as it causes people to engage and interact with a distinct set of muscles in the face that make up the recognizable surprise expression (Hastings et al., 2008).

## Bayesian Theory of Surprise

The concept of surprise is central to sensory processing, adaptation and learning, attention, and decision making. Yet, until now, no widely-accepted mathematical theory existed to quantify surprise elicited by stimuli or events, for observers ranging from single neurons to complex natural or engineered systems (Baldi & Itti, 2010). Bayesian surprise quantifies how data affects natural or artificial observers, by measuring differences between posterior and prior beliefs of the observers (Baldi & Itti, 2010).

## Mathematical Definition of Surprise

Surprise is a general, information-theoretic concept, which can be derived from first principles and formalized analytically across spatio-temporal scales, sensory modalities, and, more generally, data types and data sources (Rodgers, 2010). Two elements are essential for a principled definition of surprise. First, surprise can exist only in the presence of uncertainty, which can arise from intrinsic stochasticity, missing information, or limited computing resources (Rodgers, 2010). Two elements that are essential for a principled definition of surprise are (Rodgers, 2010):
* Surprise can exist only in the presence of uncertainty, which can arise from intrinsic stochasticity, missing information, or limited computing resources. A world that is purely deterministic and predictable in real-time for a given observer contains no surprises.
* Surprise can only be defined in a relative, subjective, manner and is related to the expectations of the observer, be it a single synapse, neuronal circuit, organism, or computer device. The same data may carry different amounts of surprise for different observers, or even for the same observer taken at different times.
In probability and decision theory it can be shown that, under a small set of axioms, the only consistent way for modelling and reasoning about uncertainty is provided by the Bayesian theory of probability. Furthermore, in the Bayesian framework, probabilities correspond to subjective degrees of beliefs in hypotheses or models which are updated, as data is acquired, using Bayes' theorem as the fundamental tool for transforming prior belief distributions into posterior belief distributions (Baldi & Itti, 2010). Therefore, within the same optimal framework, the only consistent definition of surprise must involve: (1) probabilistic concepts to cope with uncertainty; and (2) prior and posterior distributions to capture subjective expectations. Specifically, the background information of an observer is captured by his/her/its prior probability distribution over the hypotheses or models M in a model space.
Given such a prior distribution of beliefs, the fundamental effect of a new data observation D on the observer is to change the prior distribution {P(M)} (for all models M in the model space) into the posterior distribution {P(M|D)} via Bayes' theorem, whereby:
In this framework, the new data observation D carries no surprise if it leaves the observer's beliefs unaffected (Baldi & Itti, 2010), that is, if the posterior is identical to the prior; conversely, D is surprising if the posterior distribution resulting from observing D significantly differs from the prior distribution (Rodgers, 2010). Therefore the surprise is measured by quantifying the distance (or dissimilarity) between the posterior and prior distributions, and is best done using the relative entropy or Kullback-Leibler (KL) divergence (Baldi & Itti, 2010). Thus, it can be said that surprise is defined by the average of the log-odd ratio taken with respect to the posterior distribution over the model space (Baldi & Itti, 2010).
Log-Odd Ratio:
In this instance, KL is not symmetric but has well-known theoretical advantages, including invariance with respect to ‘reparameterisations’ (Broder, Kellen, Schutz & Rohrmeier, 2013). A unit of surprise - a wow - may then be defined for a single model M as the amount of surprise corresponding to a two-fold variation between P(M|D) and P(M) (Broder et al., 2013). The total number of wows experienced when simultaneously considering all models is obtained through the integration over the model class (Broder et al., 2013).

## Essence of Surprise

An example of how surprise arises when data is observed, consider a human observer who just turned a television set on, unknowing of which channel it is on. The observer has a number of co-existing hypotheses or models about which channel may be on, for example, MTV, CNN, FOX, BBC, etc. (figure), and over the course of viewing the first few video frames of the unknown channel (here, CNN), the observer's beliefs in each hypothesis adjust (Baldi & Itti, 2010), therefore progressively favouring one channel over the others (leading to a higher prior probability for CNN in left panel). Furthermore, consider what happens if yet another video frame of the same program is observed (top right), intuitively an unsurprising event. Through Bayesian update, the new frame only minimally alters the observer's beliefs, with the posterior distribution of beliefs over models showing a slightly reinforced belief into the correct channel at the expense of the others (Baldi & Itti, 2010).
In contrast, if a frame of snow was suddenly observed (middle right), intuitively this should be a very surprising event, as it may signal storm, earthquake, toddler's curiosity, electronic malfunction, or a military putsch (Broder et al., 2013). Through Bayesian update, this observation would yield a large shift between the prior and posterior distributions of beliefs, with the posterior now strongly favouring a snow model, correspondingly reducing belief in all other television channels (Baldi & Itti, 2010). This therefore explains that unsurprising data yields little difference between posterior and prior distributions of beliefs over models, while surprising data yields a large shift (Baldi & Itti, 2010). In mathematical terms, an event is surprising when the distance between posterior and prior distributions of beliefs over all models is large (Broder et al., 2013).

## Shannon Information and the White Snow Paradox

At the time of snow onset (above figure, middle right), the image distribution expected and the image perceived are very different, thus implying that the snow ultimately carries a great deal of both surprise and Shannon’s information. While snow may be a sign of storm, earthquake, toddler’s curiosity or military putsch, no more surprise arises after the observer's beliefs have stabilized towards strongly favouring the snow model over all others (above figure, bottom right) (Itti & Baldi, 2009). Thus surprise resolves the classical paradox that random snow, although in the long term the most boring of all television programs, carries the largest amount of Shannon information (Itti & Baldi, 2009). This paradox arises from the fact that there are many more possible random images than there exists natural images, thus the entropy of snow is higher than that of natural scenes (Itti & Baldi, 2009). Even when the observer knows to expect snow, every individual frame of snow carries a large amount of Shannon information (Itti & Baldi, 2009).
In a sample recording of 20,000 video frames from typical television programs, conducted by Itti & Baldi (2009), presumably of interest to millions of watchers, results measured approximately 20 times less Shannon information per second than in matched random snow clips, after compression to constant-quality MPEG4 to adaptively eliminate redundancy in both cases. The situation was reversed when results depicted snow clips carried about 17 times less surprise per second than the television clips, evaluated using the average, over space and time, and of the output of the surprise metric presented within the experiments. Thus, more informative data may not always be more important, interesting, worthy of attention, or surprising.

## Body Language

Surprise has its own unique facial expression configuration. When someone is surprised, the response from the brain and nerve endings causes people to engage and interact with a distinct set of muscles in the face that make up the recognizable surprise expression:
* Eyebrows that are raised so they become curved and high
* Horizontal wrinkles become apparent across the forehead
* Eyelids open: the upper lid is raised and the lower lid is drawn down, often exposing the white sclera above and below the iris
* Jaw drops so that the lips and teeth are parted, with no tension around the mouth
The co-occurrence of these changes in the face universally communicates that someone is typically experiencing surprised. Scientists believe that the reason for the raising of the eyebrows and the eyelids and the dropping of the jaw in surprise is to allow for the maximum intake of information in relation to the quick processing time (Barret, Lindguist, & Gendron, 2007). Even though surprise only shows itself very briefly, and can still vary in intensity, by allowing all of the senses to open, each universal emotion is able to be distinguished, as each has its own set of facial expression configurations, as well as its own function (Barret, Lindguist, & Gendron, 2007).
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 (Gross, 2010). Despite facial feedback hypothesis (facial display is necessary in the experience of emotion or a major determinant of feelings); in the case of surprise, research has shown a strong dissociation between the facial display of surprise and the actual emotional experience of surprise, suggesting that there are variations in the expression of surprise, voluntary or not (Burgoon & Jones,1976).

## Physiological Response

The startle reflex (startle response) serves as a psycho-physiological indicator of the emotional valence of foreground stimulation. The main function of 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, in particular the neck muscles. Studies show that this response happens extremely quickly, with information reaching the pons within 3 to 8 milliseconds and the full startle reflex occurring in less than two tenths of a second (Burgoon & Jones, 1976). The one core appraisal of surprise has the potential to predict the outcome of surprise; however the appraisal of the coping mechanism predicts the response beyond surprise, such as confusion or interest. If a person experiences a very powerful or long lasting surprise, this may be considered an acute stress reaction whereby the automatic redirection of focus causes muscle tenseness to be prolonged and emotion development to become confused (Silva, 2009).
Research explains that by continuously experiencing a surprised state allows the body to improve muscle functionality, brain activity and overall health as by repeatedly allowing the facial muscles to expand and stretch out there is an increase of overall blood flow and oxygen delivery (Silva, 2009). By increasing this circulation, smaller and more delicate areas of the face and brain are activated more frequently, and functionality allows for better processing time of information to and from the brain (Silva, 2009). Furthermore, with this increase in physiological response time and intellect, the body can expand its emotional spectrum to understand and express more than just basic responses (emotions) to surprise (Burgoon, Dunbar, & Segrin, 2002).
Academic sources suggest that the brain's pleasure centres are more turned on when an experience of unpredictable or pleasant encounter is apparent, compared to expected pleasant events, according to new pictures of the brain responding to surprises (Burgoon, Dunbar, & Segrin, 2002). Reward pathways responded much more strongly to the unexpectedness of stimuli instead of known pleasurable effects, with the brain's emotion centre that processes surprise from the circuitry that processes the aversive or reward valence of a stimulus being distinguished. A recent study by Emory University and Baylor College of Medicine have found that as a result of this, by understanding how the brain responds to expected vs. unexpected stimuli can help aid in developing a better understanding of human decision making and addiction in relation to a variety of lifestyle situations and influences (Malick, 2010).
Based on this, it can be assumed that the adrenaline a person experiences as a result of unexpected stimuli can create a positive acceptance of the emotion of surprise. Adrenaline, technically known as epinephrine, plays a large role in the fight or flight mechanism as the release of epinephrine is exhilarating and creates a surge in energy. Adrenaline causes an increase in heart rate, blood pressure, and works by causing less important blood vessels to constrict and increasing blood flow to larger muscles. This jolt can be healthy in small doses as the adrenaline rush tends to make people feel alive; with some people craving this unexpected state of mind in maximising the release of endorphins over their life time.

## Reality Construction

Surprise is intimately connected to the idea of acting in accordance with a set of rules. When the rules of reality generating events of daily life separate from the rules of thumb expectations, surprise is generally the outcome. It represents the difference between expectations and reality, the gap between our assumptions and expectations about worldly events, as well as the predicted way that those events turn out; In essence, surprises are the end result of predictions (if made) that fail (Handel, 1984).
As a basic emotion, surprise can neither be categorised as basically positive nor as a negative emotion as it may lead equally to a positive or a negative outcome for individuals (Izard 1977). The perception of surprise as positive or negative depends on the individual; Those who mostly experience positive consequences following surprise, evaluate this emotion as positive. Those who most often have to face negative results, consequently describe it as a negative emotion. The latter are in general more anxious and afraid of unexpected and unfamiliar situations than the former (Izard 1977). Izard’s (1977) empirical study showed, that the majority of test subjects of a student population reported positive associations with surprise. Furthermore, Vanhamme’s and Snelders’s (2003) experiment shows that surprise has an effect on the positive evaluation of the surprising product attribute and also that variation in the level of surprise has a direct effect on consumers’ satisfaction. Since impulse purchasing implies approach behaviour towards a product, it can be assumed as a positive connotation of surprise.

## Conclusion

In conclusion, the emotion of surprise can be described as a sharp increase in neutral situation, typically brought about by a sudden or unexpected event. It is a brief mental and psychological state that is considered an adaptive, evolutionary-based reaction to unexpected events with both emotional and cognitive aspects. Surprise is considered a stepping stone to other emotions, can vary greatly in terms of valence and intensity, and has its own set of facial expression configuration. When someone is surprised, the response from the brain and nerve endings causes people to engage and interact with a distinct set of muscles, causing the forehead to wrinkle, eyebrows to raise, eyelids to open and jaw to drop.
Research suggests that surprise is good for human health and emotion as by experiencing random (but frequent enough) bursts of adrenaline (brought upon by the body’s response to unexpected stimuli) helps to increase the intelligence of the mind and body in expanding its emotional spectrum in the understanding and expression of more than just basic responses. Further explanation also reveals that this jolt (or surprise) can be healthy in small doses as the adrenaline rush tends to make people feel alive; with some people craving this unexpected state of mind in maximising the release of endorphins, and ultimately happiness, over their life time.