According to the Oxford English Dictionary, emotion is defined as ‘a natural instinctive state of mind deriving from one's circumstances, mood, or relationships with others’. This standard definition implies interesting characteristics about the nature of emotions because emotions involve something innate, something that we are born with. Emotions are often invoked during social interactions and aid in communicating with others by sending and receiving messages through their expressions, which can vary depending on context. Of course, many scholars have their own definition of emotions and there are many differences among those definitions.
For this chapter we define one type of emotion as transient, bio-psych-social reactions to events that have consequences for our welfare and potentially require immediate actions (Matsumoto and Hwang 2012). These emotions are biologically resident and are products of our evolutionary history, providing the platform for universality in the domain of immediate reactions (Matsumoto and Juang 2013). Our definition of emotion is based on the study of priming reactions that precede potential immediate action and that are tied to physiological responses, expressive behaviours and cognitive gating; this type of emotion is called ‘basic emotions’ (Ekman 1972) or ‘biological emotions’ (Matsumoto and Hwang 2012). These emotions are biological because they are elicited along with physiological responses from the central and autonomic nervous systems. They are psychological because they involve specific mental processes required for the elicitation and regulation of response and direct mental activities, and they incentivize behaviour. They are social because they are often elicited by social factors and have socially communicative meaning when triggered (Matsumoto and Hwang 2012).
Emotions are rapid information processing systems that help us act with minimal conscious deliberation (Tooby and Cosmides 2008). Issues related to survival such as birth, battle, death and seduction have been present throughout our evolutionary history, and emotions aided in adapting to problems that arose rapidly with minimal conscious cognitive intervention. If we did not have emotions, we could not make rapid decisions regarding whether to attack, defend, flee, care for others, reject food or approach something useful. Think about a situation in which your friends have to rapidly avoid a car that you see is coming at them; your immediate behavioural reaction such as a fearful face or gripping your seat would quickly signal to your friends with the information that something's wrong.