Imagine a situation where a young adult has to approach an attractive person of the opposite sex that he (or increasingly nowadays she) wants to ask out for a date. On one hand intense crush propels him/her forward and on the other hand there is severe nervousness due to fears of getting turned down. For a young person, getting to go out with the person one has a crush on can be gravely important and there are intense autonomic nervous system / bodily reactions such as heart beating faster, voice cracking, and palms sweating. Imagining a situation such as this, one can appreciate the significance of emotions in bringing about motivation to select and pursue goals in life. Indeed, one is constantly being pushed towards certain things and repelled away from certain others due to anticipation/prediction of rewarding and unwanted outcomes, respectively.
Despite the significance of emotions for human cognition, it was still not long ago that cognition was surprisingly widely thought to be separable from emotions. It was also widely held that emotions would be too difficult and elusive a phenomenon to study rigorously in laboratory or neuroimaging settings. As a result of this, the bulk of cognitive neuroscience research has in the past focused on studying cognitive and perceptual processes. Research on emotions and the underlying neural mechanisms has only begun to flourish relatively recently. This surge in interest towards emotions is highly important, given that emotions are the core driving force that builds motivation and influences goal directed behavior; in many ways cognition and perception are never quite separable from emotions. To begin the description of cognitive neuroscience of emotions, different ways that emotions have been defined will be introduced first.
Definitions of emotions
When observing the behavior of lower animals, it becomes obvious that emotions are behaviorally manifested in two types of behavior: the animals are attracted towards certain objects in their environment such as food, sweets, or water, and withdraw or flee away from others, such as threatening predators. In humans, of course, emotions are manifested in a more complex manner than (at least what can be observed) in animals, and there are countless words for different flavors of emotions and feelings, such as angry, longing, sad, depressed, melancholic, happy, overjoyed, in love etc. This has motivated researchers to attempt to define “core” or “basic” emotional states.
Certain well established definitions of emotions go even further in the attempt to reduce dimensionality of emotion definitions, and are not all that different from what is seen in emotional behaviors of animals. In these models, where emotions are placed on two dimensions called valence and arousal, emotions are seen as helping humans to adapt to the environment as optimally as possible, by allowing determination of whether something is good or bad, and how significant it is. To complement these views, there are separate definitions for aesthetic emotions as the definitions of basic/dimensional emotions have failed to capture the breadth of feelings that occur when, for instance, listening to music or watching movies (Zentner et al., 2008). The models of basic emotions and dimensional emotion models are outlined in more detail in the following.
Basic emotions: anger, disgust, fear, happiness, sadness and surprise
In search for human core emotions, researchers have shown sets of photographs displaying faces expressing various emotions to subjects from different cultures. This way, it has been possible to show that there are at least six emotional expressions that are relatively consistent across cultures (Ekman et al., 1969). These emotions are anger, disgust, fear, happiness, sadness, and surprise . The fact that these “basic” emotional expressions are present across cultures has been taken to suggest that they are based on human biology rather than shaped by culture. The number of basic emotions has been a topic of some debate. There is evidence suggesting that contempt would be a distinct, culturally universal, seventh basic emotion (Ekman and Heider, 1988). On the other hand, it has been sometimes argued that surprise would not be a genuine basic emotion, as it is easily confused with fear. Nonetheless, the theory of basic emotions has been a very influential one in cognitive neuroscience.