What do categorical approaches to the structure of affect look like? - Chapter 4

How could emotions be divided in discrete categories?

Many researchers see emotions as examples of discrete categories such as anger, fear, sadness, happiness and so on. Often a small number of emotions are also seen as basic or primary emotions, because these emotions are seen in all cultures. It is assumed that different emotions have different neurological structures, which are directly and automatically activated by the right stimuli or evaluations. It is important to mention that when we talk about basic emotions, it often concerns groups of related affective states with shared traits (emotion families), rather than specific emotions.

What do we mean by basic emotions?

Basic emotions are seen as the emotions that are important for the survival of the species, society or the self. This biological approach is the most common, but biological mechanisms only cause limitations on behavior. Social factors are also an important factor in the development of basic emotions. Think of emotions like amae in Japan. Amae is seen there as basic emotion, while it does not occur in other cultures.

The category approach, which states that emotions are characteristic of different categories (some more basic than others), remains the most dominant approach to date. Basic emotions are linked to internal body processes that arise from certain neural structures. They are triggered by emotionally-competent stimuli and can influence both cognitive processes and action tendencies. In addition, every emotion has a unique feeling. The most important element that distinguishes emotions from each other is that our appraisal of an event is influenced by our ancestors, so by evolution.

Which criteria do we have for basic emotions?

The central idea of ​​a discrete emotion response is that as soon as an emotion arises, a set of easily recognizable behavioral and physical responses is triggered. These responses are coordinated over time and correlated in intensity. Levenson states that as soon as an emotion is activated, a number of subroutines for the different response systems are activated, with feeling as the most important. The others are facial expression, verbal expression, motor action and physical activation. An emotion can arise as an immediate consequence of an event, or through an evaluation of the event.

There is still no clear set of criteria for distinguishing basic emotions. Because different criteria are always used, other emotions are always designated as basic emotions. Due to this lack of agreement, the existence of basic emotions is sometimes called into question. However, despite all the different theories and criteria, many researchers agree that happiness, fear, anger, disgust and sadness are good examples of basic emotions.

What empirical evidence exist for discrete emotions?

Every emotion is characterized by certain signals to communicate the affective state to others. Tomkins was the first who identified specific response patterns for the different emotions in people. Most research into this has its focus on facial expression, but verbal expression research has also been done. Both are further explained below.

How could different facial expression be recognized?

Some emotions are characterized by the same facial expressions in different cultures or even in different animal species. Early research looked at whether people were able to recognize emotions from facial expressions based on photos. The problem with this was that people used too many different words to describe certain expressions. This resulted in the method whereby people were asked to choose the best description for each photo from a limited number of labels. These labels were usually the six basic emotions mentioned above. This technique improved the accuracy considerably.

Cross-cultural studies also showed a lot of similarity between people, but these results were questioned because there might have been influences from Western television. The solution to this was a repeat of the study in New Guinea, which examined a group of people who were very isolated and had virtually no contact with Western society. A great deal of agreement was also found among these people. Finally, photos were also made of the New Guineans who expressed different emotions. These emotions were then correctly identified by American students. The conclusion from this was that certain emotions are really universally determined.

One criticism of these theories is that the use of predefined labels can lead to an increased degree of agreement. In addition, it may be that not the facial expressions, but certain components of them (frowned eyebrows) are the universal signal.

How are intonation and vocalization recognized?

You can also communicate emotions through vocalization. Some vocalizations are probably also universal, for example the 'yuck' sound we make when we feel disgust, or a scream of fear. The method for examining this is similar to that for examining facial expressions: participants listen to sentences pronounced with a certain emotional tone and the participant must identify the emotion on the basis of a number of choices. The agreement between the participants was quite high, but most of the criticisms of the research into facial expressions also apply here.

Despite the small number of cross-cultural studies, it seems that some emotions are universal in their vocal expressions. It is true that the less the speaker's language resembles that of the participant, the less well the emotion is recognized. So it seems that culture influences the verbal expression of emotion.

Neural activity can also be seen in the auditory cortex. Participants in a Grandjean study had to assign a gender to a voice they heard. The voice spoke a non-existent language in a neutral or angry tone. The angry tone caused increased activity in the superior temporal sulcus, suggesting that brain responses are enhanced by the presence of threatening information.

Social interaction can also play a major role in recognizing emotional intonation (the same applies to facial expression). There is always some interaction between the speaker and the listener. Unfortunately, these complicated and rapidly changing processes are difficult to capture in a laboratory study, which means that not much research has yet been done into this effect.

What about distinctive physiology?

What is the evidence for emotion-specific autonomic nervous system activation?

An important question in emotion research is whether each emotion is associated with a specific pattern of physiological responses. Many studies have investigated the extent to which each emotional state is associated with unique activation of the autonomic nervous system (autonomic nervous system (ANS)). This system regulates the automatic systems in the body (heart and blood vessels, digestion, breathing, etc.).

Because the function of the ANS is to ensure a consistent and stable physical state (homeostasis), it is likely that the response to many emotions is largely the same. Levenson, however, states that when an emotion requires very specific behavior, this can also be seen as a specific change in ANS activity. Anger and fear are good examples of such emotions. Ekman also found that emotions can be distinguished by specific patterns in ANS activation, through his research in which participants were asked to form certain facial expressions. This was done by specific directions ("raise your eyebrows"). When the facial expression looked like a prototypical expression for an emotion, people also felt this emotion more often. This research has been repeated in other cultures and there it was found that certain ANS activation patterns are universal.

What are the distinctive neural circuits?

If there is a set of basic emotions, we could expect neural activation patterns that are specific to each of these emotions. A lot of research has been done on this in both animals and humans, as will be discussed below.

What are the results of animal research?

Some research focuses on identifying neurochemical systems that influence emotional responses. Other research looks at the role of specific anatomical structures in the brain that influence the learning and expression of certain emotions. Panksepp states that affective processes arise from subcortical emotion-action systems that lead to unique affective experiences of feeling. The systems are universal for mammals and were created by evolution. This could be investigated by researching animals, but the criticism is that many species only have emotions and no feelings. Some other researchers state that feelings are not at all more important than other aspects of emotion. Still others find it easier to study feelings in people, where they can be measured much more directly.

Panksepp's approach: emotion action systems

Panksepp states that the functioning of neurotransmitter systems is the most important aspect of emotion-action systems. According to him, we need to examine animals under natural conditions so that the neurotransmitters that are important for specific systems can be identified. These transmitters can then be manipulated by drugs to see what effect this has on subjective feelings.

A conclusion of Panksepp is that affective processes in the brain can be divided into three general categories that differ in the degree of complexity: reflective affects, Blue-ribbon (grade A emotions) and higher sentiments. The idea is that the basic emotions originate in the mid brain and that the frontal cortex causes the more complex emotions such as shame, guilt, jealousy, etc. Panksepp also states that there are seven primary affective systems that can be seen as the basis and that we owe to evolution. The table below shows which seven systems these are with their most important neurotransmitters:

* (-) means that the neurotransmitter inhibits the prototype and (+) means that the neurotransmitter activates the prototype

Oxytocin, mother care and romantic love

The peptide oxytocin is crucial for the development of maternal behavior, attachment and possibly even romantic love. It is important for female sexuality and plays a role in childbirth and breastfeeding. In addition, it has a broader role in the development of nurturing and maternal behavior. Differences in this behavior appear (according to research in rats) to be directly related to differences in the amount of oxytocin receptors; the more receptors, the less anxious and the more maternal. There is also evidence of a link with the panic system: the more oxytocin in the brain, the less distress signals a rat emits when it is separated from the mother.

The question is whether oxytocin really influences maternal feelings, or rather directly triggers specific maternal behaviors. These behaviors can, of course, occur without feelings being involved. Research has shown that attachment is accelerated by a larger amount of oxytocin, but it is not clear whether this is mediated by feelings. No research has been done in humans on the link between oxytocin brain activation and subjective feelings. There has been a study that looked at the link between oxytocin reactivity and subjective feelings of love. This showed that there was a correlation with the behavioral indicators of love, but not with subjective feelings. This is therefore an indication that oxytocin has no direct influence on feelings.

The LeDoux approach: fear conditioning

Much of what we know about the neural pathways involved in anxiety comes from studies on anxiety conditioning. Hereby a conditioned response is taught (an anxiety response) to a conditioned stimulus (usually a sound). This is done by following the sound with a painful stimulus that causes anxiety. After a few times the fear already arises as a reaction to the sound, without the painful stimulus being present.

The amygdala is the most important brain structure in anxiety. This consists of three important parts: the corticomedial nuclei, the basolateral nuclei and the central nucleus. There are two routes that a stimulus can take. The low road is the fastest route, the stimulus goes directly from the thalamus to the amygdala. The high road is slightly slower, with the stimulus going from the thalamus to the auditory cortex and from there to the amygdala, so that the stimulus is also consciously observed.

Contextual fear associations occur when an individual is already developing a fear response for the space in which the response is conditioned, even without a conditioned stimulus being present. This is due to the hippocampus, which is related to episodic memory.

Extinction occurs when the conditioned stimulus occurs very often without the painful stimulus, so that the individual learns not to be afraid of this stimulus anymore. The fear response will gradually decrease and eventually disappear. This learning process takes place primarily in the medial PFC, along with other cortical areas, and affects how the amygdala and hippocampus respond to situations and stimuli.

What are the effects of amygdala damage in non-human primates?

Removing the temporal lobe (which contains the amygdala) leads to Kluver-Bucy syndrome in monkeys, which causes the monkeys to become very tame and not aggressive. In addition, they were no longer afraid of stimuli for which they were afraid before the procedure. Other effects of the procedure were hypersexuality and a tendency to eat non-edible things, such as stones and droppings. Because more was removed than just the amygdala, these effects may also be due to other parts of the brain, but the lack of fear responses later showed that this was due to the removal of the amygdala.

Research into damage to the frontal lobe shows that this part is important for controlling the emotional response. For example, disturbances may arise in the expression of emotions (facial expressions, etc.) and disruption of social behaviors. The proper functioning of amygdala and PFC is therefore critical for the development of social behavior.

Human research: Lesion studies

Much of the knowledge about how emotions manifest themselves in the human brain comes from studies on people with brain damage, often caused by a brain haemorrhage, tumor or accident. A well-known example is Phineas Gage, who got an iron rod through his head, thereby damaging his PFC, but surviving the accident. He didn't have any motor or language problems, but his personality changed from reliable, kind and hardworking to unrestrained, impatient and he no longer took others into account. Phineas Gage was proof that the PFC is largely responsible for regulating emotions.

People with damage to the amygdala mainly saw a change in emotional behavior, mainly a reduction in the recognition of anxious faces. Recognition of other emotions remains intact.

Damage to the insula and basal ganglia causes people to have difficulty recognizing faces and vocalizations that express disgust. The recognition of fear and anger remains normal. Research into patients with Huntington's (where the striatum, part of the basal ganglia, is damaged), also showed that this brain area influences the recognition of disgust. Damage to the ventral basal ganglia, however, is again related to the recognition of anger.

Experiencing the emotions above is also influenced by brain damage. However, it is not the case that people with these lesions no longer feel the emotions involved, they only feel them in a different way or at different moments.

What are the results of fear conditioning in patients with brain damage?

For fear conditioning in humans, skin conduction is often measured, this is a good indicator for ANS activation. Several studies have shown that the amygdala is indeed crucial for the development of conditioned anxiety in humans. The hippocampus appears to be responsible for explicitly learning an anxiety response.

Patients with amygdala damage are able to learn which conditioned stimuli are linked to certain unconditioned stimuli, but they do not develop the associated fear response. Patients with damage to the hippocampus, on the other hand, were unable to learn which stimuli belonged to each other, but did develop a normal conditioned fear response. Patients with damage to both brain areas could not learn which stimuli belonged to each other and also did not develop a conditioned fear response. This indicates that explicit / hippocampal representations arise so that we know that a dangerous situation can occur, even though we have never experienced that immediately. Implicit / amygdala representations, on the other hand, arise so that we can respond immediately to a threat, even if we do not explicitly know what this threat is.

Is the amygdala specific to fear?

In addition to fear, the amygdala also appears to be involved in a number of other emotions. For example, certain neurons are activated by both reward-related and punishment-related stimuli. The amygdala also responds to a series of positive stimuli, but this response is strongly influenced by personality traits. The amygdala is therefore not only involved in fear responses.

How are emotions seen with brain imaging?

Brain imaging makes it easier to investigate which parts of the brain are responsible for certain emotions, including healthy participants. Many of these studies have investigated emotion perception by presenting an emotional stimulus and looking at which areas of the brain are triggered by certain emotions. Usually photos of facial expressions are used for this.

Early research found very different results, probably due to the low number of participants in each study. That is why meta-analyzes were done, in which a large number of similar studies are combined to create a greater statistical power. Murphy's meta-analysis found that certain areas of the brain are more often activated for certain discrete emotions:

1. Anxiety - amygdala

2. Disgust - insula / operculum and globus pallidus

3. Anger - lateral orbitofrontal cortex

4. Happiness - rostral supracallosal ACC / dorsomedial prefrontal cortex (dmPFC)

5. Sadness - rostral supracallosal ACC / dmPFC

So it seems that there are clearly separate areas for fear, disgust and anger, but not for happiness and sadness. Furthermore, areas in the PFC and ACC were activated with all emotions, indicating that these areas probably play a more general role.

What are distinctive antecedent events?

An important characteristic of a basic emotion is that it must be preceded by a distinctive antecedent event, otherwise the emotion cannot be seen as important for survival. These events can cause emotions through two types of stimuli: biologically primed stimuli and stimuli that trigger responses through learning experiences. For example, you can learn to be afraid of something (such as with conditioning), or you are naturally afraid of snakes, even if you have never seen a snake before. In many cases, a combination of these two variations plays a role.

This became apparent in a study by Mineka, where monkeys who had never seen a snake or a bunch of flowers (and neither of them were afraid of the investigation) were shown a movie in which an adult monkey showed a fear reaction after seeing a snake, or after seeing a bunch of flowers. The young monkeys then only showed a fear reaction after seeing a snake, not near a bunch of flowers. This indicates that a selective learning process (influenced by biological factors) is underway.

What are appraisal model of emotions?

It is clear that a certain set of prior events do not always cause the same emotions in everyone. It is the appraisal of the situation that gives this meaning and then causes a basic emotion. Viewed in this way, basic emotions can be reduced to basic appraisal scenarios. This involves a small set of behavioral goals, associated with a core set of appraisals. These are the same in all cultures, demonstrating that the appraisals linked to these goals result in the basic emotions.

According to Arnold, appraisals are based on three dimensions: whether the situation is beneficial or harmful, whether an important object is present or absent and whether the object is difficult to approach or to avoid. These appraisals of whether a situation influences the self result in specific action trends that are experienced as emotions. Fundamental appraisal is experienced across all cultures and leads to basic emotions, or modal emotions in this study.

Richard Lazarus

His cognitive-motivational-relational theory describes that every discrete emotion is associated with a core relational theme. An appraisal of such a theme leads to an emotion. For example, a core relational theme such as facing an uncertain threat leads to the emotion of fear. However, the list is very similar to a list of definitions of the different emotions and is therefore not worth much as an explanatory model.

Oatley and Johnson-Laird

A function of discrete emotions is to ensure that important life goals can be achieved. The idea is that an event is assessed in relation to various goals. This happens automatically and unconsciously and is driven by a small number of basic emotions. According to them, a complex organism like us humans has two major problems: personal goals and the unpredictability of the environment. The goals can be conflicting and therefore some goals must be given priority. Emotions are used to give these goals priority and to adjust the schedule when an unexpected event occurs. The different changes are related to specific basic emotions and can be identified by cognitive evaluations.