20 Module 20: Emotions and Motivation: What Moves You?

Module 20. Emotions and Motivation: What Moves You?

Have you ever noticed the similarity between the words emotion and motivation? It is not coincidental. The Latin stem, -mot, means “move.” This linguistic similarity will help you understand the relationship between the psychological conceptions of emotion and motivation. In many cases, an emotion is something that motivates you. For example, if you are happy, you are energized to do something that you believe will help you maintain the happy feeling. If you are angry, you may be motivated to act aggressively against the person who made you angry.

This module explores two topics, emotion and motivation, that do not fit neatly into the social psychology subfield. Emotion does not fit, perhaps, because it might just deserve to be a subfield by itself. Some observers have noted that historically, cognition (a subfield) and emotion have vied for the position of psychological primacy. Although cognition has “won” in many camps, one can make a good case for the importance of emotion over cognition (Zajonc, 1998). For example, emotion seems much more critical for survival than cognition. It is because of our emotional responses that we can recognize something as threatening or safe, far earlier than we recognize what it is. If emotion does indeed deserve at least equal billing with cognition, it hardly seems fair that cognition is allotted an entire subfield while emotion is pigeon-holed into the best fit among the existing subfields, social psychology.

Motivation, as you will see, is really too broad to fit neatly into a subfield; it encompasses any behavior that is not automatic. It would be reasonable, then, to place motivation into any (really all) of the subfields. But because that is not really possible, psychologists tend to place it along with emotion because of the similarities.

This module has three sections. Section 20.1 is about general concepts in motivation and pursuing goals. You will find additional topics related to motivation throughout the rest of the book, (as in the discussion of specific types of motivations in Module 19 (sex), Module 22 (sleep), Module 23 (hunger), and elsewhere. Section 20.2 is about emotions; it begins to define emotions and describes the changes in brain, cognition and body that mark them. Section 20.3 focuses on one particularly important emotion in everyday life, anger, and its most obvious and sometimes-explosive response, aggression.

20.1 Motivation and Goals

20.2 Emotion, Brain, Body, Cognition, and Expression

20.3 Anger and Aggression



Remember and Understand

By reading and studying Module 20, you should be able to remember and describe:

  • Drives and incentives, basic motivations (20.1)
  • Nucleus accumbens, dopamine and reinforcement (20.1)
  • Goals, intrinsic vs. extrinsic motivation (20.1)
  • Self-regulation and self-control (20.1)
  • Key observations about emotions (20.2)
  • Emotional triggers (20.2)
  • Basic emotions: anger, fear, contempt-disgust, sadness, happiness, surprise (20.2)
  • The amygdala (and other brain areas) and emotions (20.2)
  • Autonomic nervous system arousal: problems with the polygraph (20.2)
  • Interactions between emotion and cognition (20.2)
  • Mood-congruent memory, hot cognition, and motivated skepticism (20.2)
  • Verbal and nonverbal expressions of emotion (20.2)
  • Gender differences in emotion: empathy, display rules (20.2)
  • Consequences of anger (20.3)
  • Types of aggression: instrumental and hostile (20.3)
  • Gender and aggression: relational and physical aggression (20.3)
  • Biological causes of aggression (20.3)
  • Social learning and aggression (20.3)
  • Aversive conditions and aggression: catharsis (20.3)


By reading and thinking about how the concepts in Module 20 apply to real life, you should be able to:

  • Use principles from self-regulation to improve goal-related outcomes (20.1)
  • Identify emotional triggers (20.2)
  • Find examples of the interactions between emotion and cognition (20.2)
  • Identify risk factors for aggression in yourself or others (20.3)

Analyze, Evaluate, and Create

By reading and thinking about Module 20, participating in classroom activities, and completing out-of-class assignments, you should be able to:

  • Identify a goal and develop a plan to achieve it (20.1)
  • Judge whether verbal and non-verbal expressions of emotion match (20.2)
  • Identify specific criteria that you use to decipher facial expressions (20.2)


20.1. Motivation and Goals


  • What motivates you to do your best in school?
  • Can you see any parallels between your school motivation and motivation in other areas of your life?


Motivation in general is an internal desire or need that energizes an individual and directs his or her behavior. Any time you do something that is not automatic, motivation is involved. Although this definition is a good starting point, it really does not provide us with a great deal of understanding about what motivation is. In particular, when you read this definition, you may be left with two important unanswered questions:

  • What exactly is motivation? In other words, is there some way to recognize when an individual is motivated—for example by examining brain activity?
  • What are the different entities that create “internal desire”?
motivationan internal desire or need that energizes an individual and directs his or her behavior


What is Motivation?

Your conscious experience when you are motivated is that you “want or need to do something.” Psychologists often refer to the internal body state that characterizes a motivation as a drive, a feeling that most people would describe as a want or a need. Basically, you can think of the drive as the “energize” part of the motivation definition. Having a drive alone, however, may not be enough to direct our behavior because we may not know how to act on the drive. Often, we need some external cue, an incentive, to provide that direction. For example, imagine that you are experiencing a drive: hunger. Many different cues in the environment may be incentives for you to act on that drive. Imagine that there is a plate of fresh-baked cookies on the kitchen counter. Almost without thinking, you might pick up a cookie and eat it.

drivethe internal body state that characterizes a motivation

incentivean external cue that directs motivated behavior

With such a broad idea of motivation, it is easy to believe that no single brain area is key to motivated behavior. Many researchers have devoted themselves to studying a particular important motivated behavior, such as sexual behavior or hunger, and examining the brain areas that are involved. This section will look at more general conceptions of motivation.

Some characteristics appear to be common to nearly all motivated behavior, and so a few brain areas may be particularly important. Many researchers have turned to the concept of reinforcement. It is probably fair to say that behavior that occurs because it has been reinforced is motivated behavior. So, if researchers could discover a brain area that is key for reinforcement, it would shed a great deal of light on motivation, agreed? Neuroscientists believe that they have found such an area. It is a section of the brain very near the hypothalamus called the nucleus accumbens. Over 60 years ago, rats that had been fitted with electrodes that electrically stimulated the brain areas near their nucleus accumbens would press a lever 2,000 times per hour in order to receive that stimulation (Olds & Milner, 1954; Olds, 1958). This area uses the neurotransmitter dopamine, so researchers believe that this particular neurotransmitter is also a key to reinforcement and thus motivation. Other researchers working with rats have verified that dopamine in the nucleus accumbens seems to be the important neurotransmitter for motivated behavior (Basareo, et al. 2003; Salamone & Correa, 2002). Dopamine is also released during sexual behavior in rats, a famously motivated behavior (Lorrain et al. 1999).

When you start to examine the research literature on the role of dopamine and the nucleus accumbens in motivation, you quickly get the impression that we know an awful lot about the sex lives of rats but not too much about humans. That is not the case, however. Studies using fMRIs have consistently shown that brain activity in the nucleus accumbens increases when people engage in reward processing (Wang, Smith & Delgado, 2016). We certainly do not mean to suggest that the nucleus accumbens is the only area that is key to motivation. Many additional brain areas that are likely important for motivation, in general, are the same ones that are key to emotions, such as the amygdala and areas throughout the cortex.

nucleus accumbensa brain area near the hypothalamus that appears to be key for reinforcement and motivated behavior

Human beings have a set of basic biological motivations, similar to the rest of the animal kingdom. These basic motivations are for behaviors that helped our ancestors survive and reproduce. The most fundamental motivations are to approach something good and to avoid something bad or dangerous. More specific basic motivations include the drive to reproduce, hunger and thirst, the need to sleep, and pain avoidance. Sex, sleep, and hunger, three very commonly discussed motivations, are covered in Modules 22, 26, and 27, respectively.

For now, it is worth noting that although humans, chimpanzees, pygmy marmosets, and jellyfish may share these biological motivations, they are scarcely recognizable across species. As you know, humans have a highly developed cerebral cortex; axons from the nucleus accumbens, a sub-cortical area (meaning it is located underneath the cortex), form synapses throughout the cortex. Both cortical and sub-cortical areas, then, are heavily involved in motivation (and emotion, for that matter). The participation of these diverse areas leads to very flexible motivated behavior in humans. For example, whereas a jellyfish probably does not have too many interesting variations in sexual behavior, a quick examination of a book like the Kama Sutra reveals an amazing diversity of sexual variation in humans. A good shorthand reminder of the difference is that non-human animals tend to engage in motivated behaviors in fixed patterns that are tightly regulated by sub-cortical brain areas and hormones. Humans, on the other hand, depend heavily on both cortical and sub-cortical areas, allowing them great variety in their motivated behaviors.

Abraham Maslow was a key early psychologist who tried to make sense of the different types of motivations that guide human behavior. He ordered these motivations in what was known as a hierarchy of needs that ranged from basic survival motivations at the bottom, through more interpersonal motivations (such as belongingness), through what he called self-actualization, the need to devote oneself to a higher purpose, such as religious or political freedom, or to put the needs of society ahead of one’s own. Although Maslow’s ideas were very influential at one time, and are still well-known outside of psychology, they do not have much influence within psychology at the present.

The Importance of Goals in Motivation

One important way to understand the complexity of human motivation is to focus on how they are related to goals. A goal is a cognitive representation of an outcome that influences our thoughts, evaluations, emotions, and behaviors (Fishbach & Ferguson, 2007). A goal is what allows us to focus and direct the energy that comes from motivation directly on specific behaviors and possible outcomes. And it is that cognitive representation part that makes our goals interesting, complex, and, well, human.

For example, consider an important distinction between types of goals that allow a basic categorization of motivations in intrinsic motivation and extrinsic motivation. If we see a specific behavior as a means to a more desired end, we call that extrinsic motivation. In other words, we have a desired goal, and we engage in an activity in order to achieve that goal. For example, suppose your goal is to be a lawyer and you work hard in school because it will allow you to achieve that goal. It is termed extrinsic because the goal is outside of (extrinsic to) the activity itself.  However, consider a different possibility. What if the goal is the behavior? In other words, the activity or behavior itself is rewarding. This is called intrinsic motivation. Here, it is intrinsic because the goal is part of (intrinsic to) the behavior. A person engages in a particular behavior, in most cases, for a combination of extrinsic and intrinsic rewards. It is not an either/or proposition (no false dichotomy here!). Still, it is useful to characterize a particular behavior is driven primarily by intrinsic or extrinsic motivation. This becomes important when you consider the rest of the definition of a goal above because the two motivation types lead to different emotions, evaluations, and behaviors. For example, one obvious benefit of intrinsic motivation is that because the tasks you are engaging in are rewarding almost by definition you will derive more satisfaction from these tasks than extrinsically motivated people do. Also, intrinsic motivation is associated with more excitement and confidence, better performance, more persistence and creativity, more vitality, higher self-esteem, and better general well-being (Ryan & Deci, 2000). Tasks that are motivated only extrinsically are judged to have no value, except as they relate to the direct achievement of some other goal (have you ever heard someone talk about how worthless some particular class is because it will not be relevant to their future career?).

We are not saying that extrinsic motivation is useless. It can certainly be effective and has an important role in human behavior. For example, students who are highly motivated by the desire for a future career often study very hard indeed. And sadly, there are many situations in which unpleasant tasks must be done. Extrinsic motivation may be the only way to motivate someone to complete these tasks. Keep in mind, however, that extrinsic motivation must be supplied continually. If the external reward is removed, the behavior might stop.

As we said, people typically engage in tasks for both intrinsic and extrinsic rewards. There is, however, an important relationship between the two, a negative relationship. Specifically, the more extrinsically motivated people are, the less intrinsically motivated they tend to be. For example, people who are extremely extrinsically motivated at their jobs (they are doing it for the money only) commonly enjoy their jobs less than people who are intrinsically motivated. Certainly, some people are highly motivated both extrinsically and intrinsically, but they are far less typical than people who are high on one and low on the other. The loss of enjoyment in the task that often accompanies extrinsic rewards can be avoided. The key is to make the extrinsic rewards meaningful, to relate them clearly to good performance.

goal: cognitive representation of an outcome that influences our thoughts, evaluations, emotions, and behaviors

extrinsic motivation: motivations that are associated with the benefits associated with achieving a goal

intrinsic motivation: motivations that are associated with the process of pursuing a goal

Self-regulation and Achieving Goals

Self-regulation is the term that refers to the complex processes through which we change our thoughts, emotions, and actions when pursuing a goal (Baumeister & Monroe, 2014). It is how we get ourselves to do things when intrinsic motivation is absent on its own. Some of the individual processes it includes are goal setting, planning, organizing and coding information, metacognition, modifying self-motivating beliefs, managing time, deriving satisfaction or pride from activities, and controlling actions and choices (Vancouver, 2018). As you can see, self-regulation is an enormous topic, and we can only begin to describe some of its important aspects.

To begin, though, let us stay with intrinsic and extrinsic motivation for a bit. Although it is not always possible to make activities enjoyable, we might be able to modify some of our beliefs and some of our choices (i.e., self-regulate) to make unpleasant tasks more bearable. For example, perhaps you make activities approach intrinsic motivation by being autonomous, in other words, making your own choices (Deci and Ryan, 2000). For example, maybe you have the opportunity to choose a topic or choose a method for achieving a course goal in a class you do not enjoy (for example, some teachers may offer the option to write a paper or give a speech about some course topic). By emphasizing your choices, your autonomy, you may be able to move an unpleasant task closer to intrinsically motivating. Another strategy is to look for opportunities to develop mastery of some behavior or information. What about the activities that you just cannot approach intrinsic motivation for? How do you get through a required class that you dislike with a teacher that you detest, for example? Clearly, in this case, you would have to resort to extrinsic motivation. The key is to find or create extrinsic rewards that are personally meaningful or consistent with your values and goals. If you can recognize how the class will help you succeed in your eventual career, you will probably have an easier time enduring it. If you can internalize extrinsic goals in this fashion, you will reap many of the benefits of intrinsic motivation (Deci and Ryan, 2000). We are not saying that you will suddenly fall in love with the task, but you may surprise yourself and enjoy it, or at least endure it, more than you expected.

Another key element of self-regulation is self-control, a key element (if not the key element) of controlling your actions. So far, we have been talking about goals as if they exist in isolation. That, of course, is not the case. At any given time you have many possible goals that you might pursue, and several individual self-regulation processes are devoted to helping us choose and focus on one. To illustrate the importance of self-control, consider the common situation when you have two goals that are in conflict: one is to engage in an activity that you will enjoy yourself right now, and another is to devote yourself to something less pleasant now that will lead to a more valued goal sometime in the future. Not that you need an example, but imagine that you have a big test in a week in your most important class (and your performance so far has not been up to your own standards). But the video game for which you have been waiting for 5 months is available tonight for the first time. You know that you really should study, but. . .

Previous research and theory had suggested that perhaps self-control is some fixed resource that you can run out of. For example, what if right before you had to decide whether to play or study, you had to exert self-control to force yourself to exercise when you did not really want to. Ego depletion theory suggested that it might be much harder to choose to study because you had already depleted your store of self-control (Baumeister et al. 1998). This is a compelling idea and one that you can probably illustrate with an example from your own life. Unfortunately, however, the idea might be wrong. Ego depletion was controversial for several years while psychologists argued over whether it could be replicated or not. It was finally tested in a multi-lab preregistered replication effort (23 separate labs testing over 2000 participants), and the results revealed a very small effect size that was consistent with the possibility that the effect does not exist. Indeed, 20 of the 23 individual lab replications could not rule out the conclusion that the effect size was 0. A couple of the labs (two for one dependent variable, one for a different dependent variable) even found an effect in the opposite direction (Hagger et al., 2016). So for now, at least, we are going to say that ego depletion is not correct (keep in mind, that could change with future research).

Other famous research suggested that self-control is a trait that is revealed very early in life and has profound influences in our later success (Shoda et al., 1990). This research was dubbed “the marshmallow challenge” and was detailed in a popular book (Mischel, 2015), and was even featured on Sesame Street, in a segment that was once parodied by Stephen Colbert. In the original research, preschoolers who were able to exert self-control and avoid eating a marshmallow (or other desired treat) for 15 – 20 minutes in return for two treats were much more successful years later. The problem is, a large scale replication with more diverse participants was published in 2018 (Watts, T.W., Duncan, G.J., and Quan, H., 2018). This new version of the research found that the advantages enjoyed by the children who had exerted self-control disappeared when the children’s family characteristics and experiences were taken into account.


You may feel as if you have a pretty good idea of what self-control is not right now. This is not very helpful, though, is it? Right, the key question to answer is, what self-control is. We can offer two good ideas. One is essentially a recap of what we said earlier, but the second is new. First, some people have managed to get closer to intrinsic motivation for tasks that they need to do. In other words, they have focused on mastery and autonomy, for example. They have been able to redefine extrinsic rewards to be consistent with their personal values. In essence, their behavior has become self-determined (Deci & Ryan, 2000), so that they have the sense that they are choosing to do the things that they have to do.

Second, some people have learned strategies to deal with temptations. One way is to redefine a temptation to try to make it less appealing than the helpful activity.  For example, an individual might get in the habit of calculating how much exercise it will take to burn off the calories contained in an unhealthy treat to make that treat seem less valued. Another strategy is to get rid of temptations before they become temptations. For example, are you irresistibly drawn to Instagram when you are trying to study? Then put your phone in another room so you cannot even see it. (Fishbach, A., Friedman, R. S., & Kruglanski, 2003; Fishbach & Trope, 2007).

self-regulation: the complex processes through which we change our thoughts, emotions, and actions when pursuing a goal


20.2. Emotion, Brain, Body, Cognition, Culture, and Behavior


  • How would you define emotion?
  • Which emotions do you think are the basic ones, common to all humans?
  • Describe the physical sensations that you have when you are experiencing:
    • Happiness
    • Anger
    • Fear
  • Make a list of the different ways that you think your emotions influence thinking processes, such as memory and reasoning.
  • How would you respond to the suggestion that sometimes, your body reactions are so similar for different emotions that you might not be able to tell the difference between them? If that is true, what else can help you distinguish the different emotions?

Emotion is among the hardest concepts for psychologists to define. Many writers talk about emotions without defining the concept at all, and others note that everything that psychologists have to say about emotions is part of the definition. One psychologist proposed that a complete definition of emotions could be found by reading the entire paper he had written in combination with the complete contents of the 10 pages of references he listed (Zajonc, 1998). In general, we agree with that approach. You can get a sense of the complexity that we are implying by looking at the title of this section (Emotion, Brain, Body, Cognition, Culture, and Behavior). If you really want to know what we mean by emotion, you will need to read the entire section (and you should probably read all of the papers and books that are referenced, too, but we will not be checking on you).

In the meanwhile, though, let us provide a shorthand definition to give us a jumping-off point: Emotionare brain-and-body states that are experienced as strong feelings, such as arousal, pleasure, or displeasure.

It is worth noting at the outset that one of the key questions about emotions pertains to the relationship between universality, aspects of emotions that are common across all humans because of our shared biology, and social constructivism, aspects that are created by individual cultures and learned by members of those cultures. We will use the somewhat more meaningful term culture (or cultural) to indicate social constructivist arguments. Culture is knowledge, customs, and other behavior that are created by a group (such as a society, ethnic group, or nation), and that members learn by being part of that group. You will notice throughout that we propose some tentative answers to these questions, but we are left with many that are still unanswered.

Five key facts about emotions are:

  • Emotions typically occur in response to something
  • There are different emotions
  • Emotions are marked by similar and distinct body states
  • Emotions interact with cognition
  • Emotions are related to behavior through expression and motivation

We will devote the rest of this section to expanding upon these five observations.

emotion: a brain and body state that is experienced as a strong feeling such as arousal, pleasure, or displeasure

universality: aspects of emotions that are common across all humans because of our shared biology

social constructivism : emphasizes that all cognitive functions are dependent on interactions with others

culture: knowledge, customs and other behavior that are created by a group (such as a society, ethnic group, or nation), and that members learn by being part of that group


Emotions Typically Occur in Response to Something

Sometimes, we experience emotion-like feelings that occur spontaneously; psychologists will typically refer to these feelings, which tend to be less intense and longer-lasting than emotions, as mood(Gendolla, 2000). In contrast, an emotion usually has an easily identified cause. Paul Ekman (2004), one of the most famous emotion researchers, has noted that the most important emotional trigger is realizing that something affecting our welfare is happening, is about to happen, or has just happened. For example, if you come home late one night to a dark house and discover that a ground-floor window has been broken and a room has been messed up, this realization is likely to trigger the emotion fear. When you realize that your house has been robbed and the culprit has left already, it is likely to trigger the emotion anger.

Other than events that impact our welfare, there are other categories of emotional triggers, though they are probably not quite as important. A second type of emotional trigger is when we think or talk about emotional experiences or imagined events. For example, if you go to your high school reunion and spend the evening talking about the fun times of old, you are likely to experience the emotion happiness. If you imagine winning the lottery, buying a new car, or even getting an A on your next big exam, you might very well experience happiness. A third key trigger for emotions is to observe them in other people. This, of course, is called empathy.

mood: an affective state that is less intense and longer-lasting than emotions

There are Different Emotions

In English alone, there are nearly 600 emotion words (Johnson-Laird & Oatley, 1989; Davitz, 1970). This is an impressive demonstration of how important emotions are in our everyday lives, but psychologists are not necessarily impressed with the sheer quantity of emotion words. Many emotional words have very similar meanings, such as anger, rage, and hostility. Instead of simply listing all of the different terms that can be used to describe emotion, psychologists have found it more useful and interesting to search for basic emotions. They have typically assumed that there is a small set of fundamental, or basic, emotions, from which more complex emotions are created through mixing. For example, Johnson-Laird and Oatley (1989) conducted a linguistic analysis of the 600 emotion words and extracted five basic emotions: happiness, sadness, fear, anger, and disgust.

If we are to identify truly basic human emotions, however, we should not limit our examination to the analysis of a single language. Instead, we should look for emotions that appear throughout the world. Paul Ekman and his colleagues (Ekman et al., 1969) were perhaps the first to examine this question empirically. They found that people in many different cultures around the world could consistently recognize six separate emotions from facial expressions: Anger, Fear, Contempt-Disgust, Sadness, Happiness, and Surprise.

These six emotions were considered the basic ones, that is, the human universal ones, for many years. The only one that you might need defined is contempt; it is a feeling of being better than someone else. More recent research, however, has begun to question this conclusion. For example, some research has suggested that anger and contempt-disgust are quite similar, as are fear and surprise. The researchers suggested that only anger and fear of these four are the basic biological emotions, and the distinctions that lead to contempt-disgust and surprise are culturally learned (Jack et al., 2014). Other research has suggested that even fear might be a distinction from anger that is learned culturally or that some cultures agreed very little with Ekman’s original labels (Crivelli et al. 2016, 2017). So it may be that there may be only three (Anger, Happiness, and Sadness) or four (plus Fear), or even fewer basic emotions. This is an intriguing idea: there may be a minimal amount of universality in emotions. Beyond that, the complexities that arise in our emotional experiences might be culturally learned.

Emotions are Marked by Similar and Distinct Body States: Physiology and Emotion

Regardless of which emotion you are experiencing, it is accompanied by physiological responses. When you are happy about a good grade or angry because a driver just cut in front of you, a great many complex events take place throughout your body. Particular areas of the brain become active, and obvious, and sometimes dramatic, changes occur throughout the body. Although some of those changes occur similarly across different emotions, others are typical of specific emotions only.

Some brain areas important for emotions

It is far too simple to say that there is an emotion area of the brain. Rather, as with all complex phenomena, an ensemble cast of many brain areas is involved. In particular, different parts of the cerebral cortex, limbic system, and the thalamus all play important roles in various aspects of our emotional experiences and expressions. That said, there is probably a star of the ensemble cast. Through the years, the one brain area that has been consistently identified as important to emotions is the amygdalathe almond shaped structures in the limbic system.

Researchers through the years have identified several different emotion-related functions of the amygdala. They can be difficult to keep track of unless you notice that there appear to be two basic functions: recognizing the emotional content of a situation and learning how to respond to similar situations in the future. In particular, the amygdala seems particularly important for helping us to recognize a threatening situation. For example, there is a direct neural pathway from the thalamus—the brain area that first receives sensory input—to the amygdala (LeDoux, 1995; Zajonc, 1998). Activity in the amygdala can lead to an instant avoidance response, before you even recognize what led to the response (as when you open a door to leave a room and are startled to see an unexpected person who is about to enter). Similarly, the amygdala becomes active when you detect a new stimulus but not when you encounter a familiar one. In cases like these, the sensory input is instantly interpreted as a potential threat (Schwartz et al. 2003). Other researchers have found that the amygdala helps us to recognize different emotions from facial expressions, a useful clue if you are trying to figure out, for example, if someone is about to punch you (Adolphs & Tranel, 2003; Yang et al., 2003). Many researchers now believe that the amygdala helps us recognize many different types of emotional situations, not only threatening ones (Ono & Nishijo, 2000).

Nearly 70 years ago, researchers discovered that electrical stimulation of the amygdala led people to report feeling fear or anxiety (Chapman et al. 1954). There is little doubt that the amygdala plays an important role in fear, an obviously important emotion in threatening situations. One key piece of evidence is that drugs that change the activity of amygdala neurons also influence fear. For example, valium is a GABA agonist—in other words, a drug that increases the activity of the major inhibitory neurotransmitter GABA. When a drug like Valium is directly applied to the amygdala, the inhibition of neural activity leads to a decrease in fear or anxiety (Davis and Lang, 2003). Valium, as you may know, is an anti-anxiety drug.

The second major function of the amygdala is to help us cope with similar situations in the future—in other words to help with learning and memory in emotional situations. During an emotional experience, the adrenal glands release stress hormones, such as epinephrine and glucocorticoids. These hormones activate the amygdala, which is connected to memory areas such as the hippocampus. The consequence is that emotional experiences are remembered better than non-emotional ones (Cahill, 2000; McGaugh et al., 2000; Pelletier and Pare, 2004). A second key way that the amygdala contributes to learning in emotional situations is through its connections to brain areas that release dopamine in the nucleus accumbens, the area that appears to be a key for reinforcement (Everitt et al., 2000). In both the memory and reinforcement situations, the amygdala’s role is to facilitate, or boost, the processes handled by the other brain areas (McGaugh et al., 2000; Parkinson et al., 2000).

Although the amygdala plays a starring role on the emotional stage, many additional brain areas are also key actors. For instance, many areas within the cerebral cortex get into the act. A full description of these areas would be well beyond the scope of this book, but I can give you an idea of a couple of important cortex functions. You may recall that we told you about an area called the anterior cingulate cortex in Module 14; it is involved in the emotional distress that accompanies pain (Rainville et al. 1997). The anterior cingulate cortex receives a great deal of neural input from the amygdala (Vogt & Pandya, 1987). It appears that the anterior cingulate cortex is involved in the recall or the conscious generation of emotions (Ono & Nishijo, 2000). Also, areas of the prefrontal cortex appear to be involved in integrating cognitive and emotional information for decision-making (Wagar and Thagard, 2003; 2004).

Autonomic nervous system arousal

The key physiological responses that take place throughout the body during an emotional episode are caused by the autonomic nervous system (ANS)—specifically, the sympathetic nervous system, which is the part that arouses the body. The amygdala has neural pathways to the hypothalamus, an important brain area for starting the autonomic nervous system (ANS) arousal (LeDoux et al. 1988).

Among the most common measures for assessing ANS arousal during emotions are the ones used in polygraph tests, commonly (but incorrectly) known as lie detector tests. The polygraph works on the assumption that when a person lies, they will experience a stress-related emotion, which will be reflected in physiological measures of sympathetic arousal, such as increases in heart rate, blood pressure, respiration, and electrical conductivity of the hand (it changes when your palms sweat). There are two major problems with polygraphs as lie detectors. First, skilled liars can learn to control some of the aroused body systems. For example, many people can reduce their heart rate and blood pressure through relaxation. Second, the sympathetic nervous system arousal that may be detected indicates that an emotion is occurring but does not indicate which emotion it is. The gross changes that the polygraph can detect are consistent with a variety of emotions. In addition, the differences in emotion between a liar and a truth-teller may be very subtle indeed, far more subtle for any technological ability to detect them. In short, the polygraph cannot tell the difference between someone who is anxious about telling a lie and someone who is anxious that the polygraph will accuse him of telling a lie. Because of the problems associated with polygraphs, it is illegal for employers (except the federal government) to use them for making hiring decisions, and they cannot be used as evidence in courts.

Just because the polygraph cannot detect physiological differences between emotions does not that mean that there are no differences. Through the years, many psychologists have believed that the type of arousal that occurs is the same for different emotions. This belief very likely stemmed from psychologists’ drawing the wrong conclusions from their limited methods of measuring arousal. Today, though, a range of methods have emerged that allow researchers to detect more subtle differences. Currently, researchers believe that ANS arousal is reliably different for different emotions (Christie & Friedman, 2004; Levenson and Ekman, 2002). For example, researchers have found greater increases in heart rate for sadness, fear, and anger compared to increases for happiness (Levenson et al., 1990). For anger and fear, the heart rate increase appears to be related to the biological “fight-or-flight” stress response (Levenson, 1992). Other physiological changes associated with fear and anger are also consistent with this idea. If you are experiencing anger, the “fight” response is activated and finger temperature increases, indicating increased blood flow to the hands so that you could use them to fight. With fear, blood flow increases to the legs with the activation of the “flight” response (Ekman, 2003; Levenson et al., 1992).

Emotion Interacts with Cognition

In the Module introduction, we noted that there has been a bit of a competition between cognition and emotion for primacy within psychology. Historically, some psychologists have argued that the fundamental processes of mental life are cognitive ones; others have argued that they are emotional ones. At this point, however, it seems clear that human mental processes and the behavior that springs from them are the products of a complex interaction between the two. You are probably not surprised to learn that emotion interacts with cognition. For example, when people are happy, they tend to interpret new information positively. When sad or angry, they interpret it negatively. So, your professor’s jokes may be funny or annoying, depending on your current emotions (Clore et al., 1993).

In addition, our memories are influenced by current emotion, a phenomenon called mood-congruent memory. We find it easy to remember other happy events when we are happy, other sad events when we are sad (Fiedler et al., 2001). We also predict the likelihood of future events with the same bias (DeSteno et al., 2000): Happy events seem more likely when we’re happy, sad events when we’re sad. Interestingly, some people can engage in mood incongruent memory as a strategy to improve their emotional state. In other words, when feeling sad, they force themselves to think of happy memories (Rusting & DeHart, 2000).

More broadly, you might realize that other aspects of thinking can be influenced by the emotions we are feeling. Psychologists refer to this idea as hot cognition, a term that refers to changes in thinking and reasoning that result from emotions and motivations (Abelson, 1963). For example, consider the concept of weak-sense critical thinking we introduced in Module 7, in which people engage in critical thinking-like behavior only for the purpose of proving their point right. This is similar to the idea of motivated skepticism, in which an individual’s emotions or motivation lead them to think critically only about information that disagrees with what they believe (Ditto & Lopez, 1992). 

hot cognition: changes in thinking and reasoning that result from emotions and motivations

mood-congruent memory: a phenomenon in which people tend to remember events that are consistent with their current emotions or moods

motivated skepticism: an individual’s emotions or motivation lead them to think critically only about information that disagrees with what they believe

Also, consider language. There is no doubt that language is deeply related to cognition (see Module 16), and in some respects, it reflects the cognition that occurs. In other words, when you “think about something,” it is likely that you “talk to yourself in your mind” in terms that reflect the way you’re thinking. Different languages across the world obviously differ in their emotional vocabulary. The question is, do the differences in language imply that different cultures do not experience the same emotions? For example, do the inhabitants of a country such as Micronesia, because they have no word for anger, not experience anger?

Above, we described some research on the still-open question about the extent to which some specific emotions are universal. It does seem pretty safe to say that it is very likely that people in all cultures throughout the world experience anger. They probably do not, however, experience it the same way, and the differences are often related to the different ways that cultures think (or talk) about emotions. Anna Wierzbicka (1999) notes that Russian has two very common words that correspond to the English word sadness. They are not synonyms and reflect common differences in Russians’ experience of sadness. One word indicates deep sadness that has a clearly identifiable cause (somewhat similar to the English grief), whereas the other is light or passing sadness that may occur for no particular reason. The fact that they are very common words suggests that both are very common emotions in the Russian experience.

There are a great many linguistic differences across cultures that suggest real diversity in emotional experiences. Indeed, research has found substantial cultural differences in the frequency of different emotions. For example, North Americans report more positive emotions and fewer negative emotions than Asians, such as Japanese and Indians (Diener et al., 1995; Scollon et al., 2004). In addition, some cultures value particular types of emotions; for example, many Asian cultures value emotions that lead a person to feel engaged with or connected to other people. An emotion like pride, which tends to separate a person from others, is not valued, and indeed Asian research participants report feeling pride less often than those from Western cultures (Kitayama et al., 2000; Scollon et al., 2004). It is likely that these linguistic differences are both a reflection and cause of these emotional differences. This interesting possibility is related to the Sapir-Whorf hypothesis, the idea that language people use, helps determine (not simply mirror) their thoughts (Sapir, 1921; Whorf, 1956).

Sapir-Whorf hypothesis: the idea that language people use, helps determine (not simply mirror) their thoughts


Emotions are Related to Behavior Through Expression and Motivation  

Our fifth key observation about emotions is that they are related to motivation and expression. We have already briefly described some of the relationship between motivation and emotion, so let us focus on expression here. The idea is that we engage in behaviors that communicate the emotion we are experiencing to other people. For example, perhaps the most obvious expression of an emotion is a verbal one; you can simply tell someone that you are experiencing an emotion. If you feel angry, you say to someone, “I am angry.” Of course, there are many additional ways that we express our emotions, and it is these nonverbal expressions that have received the most attention from psychologists over the years.

Nonverbal Expression of Emotion

Some behaviors motivated by emotion are grand displays involving words and a complex series of actions. Think of how you might react to a surprise birthday party: speechless astonishment followed by repeated assurances to the guests that you were surprised, hugs and smiles and words of appreciation. But other expressions of emotion are more subtle, taking place on a smaller scale. Tone of voice, body movements, and facial expressions can all help to convey the emotions that we are experiencing.

What happens when verbal and nonverbal expressions of emotion disagree? For example, imagine that you are having a heated discussion and you decide that the other person is angry. “No, I am not angry!” comes his or her verbal expression. At the same time, though, the person’s voice is loud and strained, and his or her lips are tight and eyebrows are low. Are you going to trust the verbal expression or the nonverbal expression of emotions? Research from nearly 50 years ago suggested that only 7% of the emotional content of a message comes from the actual words; the rest comes from vocal characteristics, such as tone of voice, and nonverbal expression, such as facial expressions and gestures (Mehrabian, 1972). People are largely aware of the relative value of the different modes of expression, too; research has shown that individuals extract more emotional meaning from vocal characteristics than from the actual words (Argyle et al., 1970).

The observations about the relative unimportance of verbal expressions of emotions have led some psychologists to ignore them completely. That is probably going too far. The dominance of vocal characteristics and facial expressions over words is evident only when they disagree with each other (for example, the words say “I am not angry,” but the facial expression says otherwise). There is little doubt that the words that people use to indicate that they are experiencing an emotion can be very important, especially when they agree with the other kinds of expressions. For example, although non-verbal expression allows an observer to figure out the approximate emotion—for example, anger—words may be essential for determining the exact emotion and what triggered it—for example, “my favorite baseball team had the bases loaded with no outs and failed to score” or “my roommate came in and changed the channel from the baseball game to Say Yes to the Dress.” In addition, the verbal communication of emotions is a key component of many psychological therapies (Fussell, 2002).

It is a mistake to ignore a verbal expression of an emotion, but we would certainly be cautious if nonverbal expression disagrees. Do not be overconfident about your ability to recognize nonverbal emotional expression, however. In general, we are good at recognizing intense emotions in others. We do not do as well with milder emotions and with subtle distinctions among emotions, and we tend to be quite poor at seeing through concealed emotions (Ekman, 2003; Ekma et al., 1999).

The type of nonverbal emotional expression that has received the most attention is facial expressions. Many aspects of facial expressions are not under our conscious control. Therefore, facial expressions cannot lie, if you know what to look for. Paul Ekman and Wallace Friesen know what to look for. They have developed a system for measuring the precise muscle movements involved when we form particular facial expressions (Ekman & Friesen, 1978; 2002). From this work, we now have detailed maps of how the parts of the face move for different emotions. For example:

  • Sadness: inner corners of eyebrows are angled upward; eyebrows are drawn together; eyelids droop; gaze is down; lips are stretched horizontally with lower lip up and corners down; cheeks are pulled up, creating a crease from nose to outside of lips
  • Anger: eyebrows are lowered and pulled together, with inner corners pointed toward nose; staring hard with eyes opened wide; jaw is pushed forward; lips are pressed together and tensed

Of course, everyone knows that the key to recognizing happiness is the smile. Although people certainly do smile when they are happy, it turns out you cannot reliably judge happiness from a smile. People smile when they want to be polite, when they want to convey that they are not a threat, and for many other reasons. Ekman notes that if you want to know whether a person’s smile really signals that they are happy, you have to look around the eyes. More precisely, the muscle that surrounds the eye causes the section of skin between the eyelid and eyebrow to be pulled down and leads to a smile that engages far more of the face than the area around the mouth.

Gender and Emotional Expression

In section 20.3, we will make the disturbing observation that aggression has a significant genetic component; hence, it is part of human nature. We also have, as part of human nature, the capacity for kindness, generosity, and sympathy. A key component of this capacity is empathy, the ability to identify with someone else’s emotions. When you experience empathy, you begin to feel the emotions that you recognize in someone else. There are large individual differences in empathy, from people who constantly cry at weddings and while watching movies to people suffering from an antisocial personality disorder (commonly known as sociopaths), who appear to experience something close to no empathy at all. According to behavior genetics research, empathy has a significant genetic component (Davis et al., 1994). It probably does not surprise you that women tend to be more empathetic than men, a difference that shows up as early as one-year-old (Trobst e al., 1994; Zahn Waxler, et al., 1992).

Women also tend to express emotions more effectively than men, but they might not feel them any differently (Coats & Feldman, 1996; Hall, 1984; LaFrance & Banaji, 1992). The difference appears to be, more than anything else, one of display rulesthe rules for how and when emotions should be expressed outwardly. In the US, for example, display rules for men dictate that they are not supposed to express sadness, fear, and embarrassment. Women are supposed to express emotions that improve relationships; for example, they should express happiness frequently and should not express anger (Brody, 2000; Hecht et al., 1993). Keep in mind that there are many individual men and women who violate the display rules and express the “gender inappropriate” emotions, but the rules do capture the average differences between men and women.

Incidentally, cultures also differ on many aspects of emotional expressions. In particular, cultures have different display rules (Ekman & Friesen, 1969), just as females and males in American culture do.  For example, in many Asian cultures, the display of anger is considered inappropriate, so Asians may often be seen smiling when they are angry. The use of specific gestures to express emotions is also different across the world.

empathythe ability to identify with someone else’s emotions

display rulesrules for how and when emotions should be expressed outwardly



  • Can you think of examples when you were successful and unsuccessful at concealing an emotion that you were feeling? Was your success or failure related to your inability to conceal, an observer’s ability to read your emotions, or both?
  • Look at your list of sayings from Activate #2. What relationships can you identify between the sayings and the material you have just read about emotional expression, gender, and culture?
  • Think about something that reliably triggers an emotional response for you. How does it relate to your personal welfare?
  • Have you experienced a situation in which emotional arousal seems to have improved your memory of the event? Can you explain in your own words why these sorts of memories are so vivid?


20.3 Anger and Aggression 


  • How often do you get angry? What are some of your typical reactions when you are angry?
  • Which of these two statements is closer to your opinion about aggression?
    • Aggression is a biological trait and therefore inevitable in humans
    • Aggression is a learned behavior and thus it can be eliminated

We often categorize emotions as positive or negative, based on how pleasant or unpleasant they feel. If we applied this categorization scheme to the list of basic emotions, we would have anger, fear, and sadness on the negative side, happiness as the one clearly positive emotion, and two unclear cases in contempt-disgust and surprise. Surprise can be pleasant (e.g., surprise party), unpleasant (e.g., threatening dog jumps at you), or neutral (e.g., you open a door to leave just as someone else is opening it to enter). Contempt and disgust, although listed together, probably differ from each other in pleasantness. Few people would judge disgust as pleasant, but regarding someone with contempt can feel very good.

This section focuses on anger, which is only one of the unpleasant emotions. Why is it getting special attention? Because it sometimes leads to aggressive behavior. Aggression has been in the news a great deal in over the years, in cases like school shootings, road rage, and terrorist activities throughout the world. Many social psychologists study anger and aggression in hope of helping to reduce their impact on members of society.

Anger: An Emotion

It is very tempting to categorize emotions as positive or negative based, not on their pleasantness, but on their consequences. We have to be careful about that temptation, however. Although a particular emotion might often lead to negative consequences, it might also often lead to positive ones. Consider anger. Consider the story of a college student who stormed off after an argument with his girlfriend one night. The next morning, he was the sorry recipient of a broken hand, a result of an angry encounter he had with a tree. (Yes, he punched a tree. The tree won.) In this case, it was clear that the anger was not positive.

On the other hand, consider perhaps the most famous bus passenger of all time, Rosa Parks. As the high school history class version of her story goes, Ms. Parks was tired and refused to give up her seat to a white passenger, as was required of African Americans in Montgomery, Alabama, in 1955. In reality, Rosa Parks was tired, not from work but from the mistreatment of African Americans that was accepted practice at that time (Parks, 1994).  Thus, one of the key events in a series that culminated in the massive progress in civil rights throughout the US was essentially motivated by anger. In this case, then, the anger was a positive emotion.

Aggression: A Behavior

An examination of the evening news, the history books, or the local playground will reveal something important about us; humans have a nasty habit of hurting each other. Psychologists define aggression as any behavior that is intended to harm or injure another living being. Note that it includes physical and verbal behavior, as well as physical and emotional harm. Killing, punching, insulting, teasing, and not letting someone “join in any reindeer games” all qualify as aggression when they are committed with the intention to harm or injure. Even without such a broad definition, aggression is depressingly common; it has been a primary goal of psychologists for many decades to understand aggression’s causes so that we may reduce or eliminate it or its consequences.

It is true that aggression need not necessarily follow from anger, but is anger necessary for aggression? Some psychologists draw a distinction between instrumental and hostile aggression. Instrumental aggression is used to achieve some other end and can presumably be committed without feeling angry. Hostile aggression is by definition fueled by anger. Some psychologists do claim that anger is necessary for all aggression (Zillman, 1988). Even if some aggression can be committed without anger, however, the distinction between instrumental and hostile aggression is not always clear. For example, although there are times when soldiers aggress dispassionately, essentially because they are following orders, it can be easy for the aggression to slip into out-of-control hostile aggression. For example, many times throughout history, military personnel have gone beyond the instrumental aggression that they were ordered to commit and engaged in anger-fueled hostile aggression (e.g., torture of Iraqis by American soldiers at Abu Ghraib).

aggression: any behavior that is intended to harm another living being

instrumental aggression: aggression that is used to achieve some other end

hostile aggression: aggression fueled by anger

It might seem odd to lump together different types of aggression, such as teasing, insulting, excluding from play, spreading false rumors, punching, and killing. There is some conceptual confusion even about the differences in physical aggression. Are the acts of punching someone and shooting someone similar in some fundamental sense, or are they different kinds of aggression altogether? Some researchers have decided to use violence and aggression interchangeably, suggesting that much of what we learn about one can be applied to the other (Ramirez, 2003). We can define violence as extreme aggression with the goal to seriously injure or kill another living being. There may be some truth to that. Have you ever seen or been in a fight where nothing mattered except hitting the other person? There were definitely times when one or both of the fighters “lost it” and began swinging and hitting uncontrollably. It is easy to imagine that if the fighter had been holding a weapon at that time, he would have used it (in our experience, it has always been a he). In some cases, at least, the difference between trying to hurt someone with your fists and shooting someone may only be a difference in the means available for acting. On the other hand, as we will see, there are some important differences between violence and aggression.

Even physical aggression and indirect aggression (e.g., verbal or relational, such as spreading false gossip) may be more similar than they appear on the surface. For example, as adolescent boys “grow out” of their aggressive phase, they appear to be replacing physical aggression with verbal taunts and other indirect kinds of aggression, so the two may serve the same function (Geen, 1998).

The possibility that different types of aggression are quite similar and perhaps substitutable for each other complicates one of the most common beliefs about aggression. “Everyone knows” that men and boys are more aggressive than women and girls. The situation is not nearly so straightforward, however. By using different conceptions of aggression, some researchers have found few differences between genders in their aggressiveness, and in some cases, they have found females to be more aggressive than males. There is no doubt that men and boys throughout the world commit more serious physical aggression and violence than women and girls (Daly & Wilson, 1988; Hilton, Harris, & Rice, 2000; Hyde, 1986). Within the confines of a heterosexual relationship, however, women may commit more aggressive acts, while men’s aggression more commonly results in injury (Archer, 2000). Other researchers have found the genders equal in verbal aggression (Buss & Dedden, 1990). If verbal and relational aggression are included along with physical aggression, gender differences in total aggression disappear (Bjorkqvist, 1994). In light of these findings, saying that “men are the aggressive gender” seems wrong.

So, what does cause aggression? I recently did an informal search using a commercial search engine for “aggression cause.” Among the first few pages of search results, I found the following factors implicated (in no particular order):

Brain injury or disorder Steroids Violent media Daycare Frustration
Alcohol or drug use or withdrawal Blood loss Peer pressure Soy Low serotonin
Hypoglycemia Poor relationship skills Rejection Processed foods 192 medical conditions
Severe infection Touch deprivation Pain Boredom Age crisis

As implausible as it may seem, all of these could be correct. That is the nature of a complex phenomenon; it has many causes, and the fact that one proposed cause is correct usually does not rule out the possibility that another factor is also a contributing cause. Although we do not have all of the answers to the question of why people behave aggressively, we have made great progress in understanding the complex set of causes. We will talk about the two broad categories of causes that have been proposed, biological and psychological. Both types include some environmental causes, so you should not think of them as substitutes for “nature” and “nurture.”

Biological causes of aggression

Many people are reluctant to grant that aggression might be biological, especially genetic, because of the assumption that explaining some phenomenon as genetically influenced means that it is inevitable. Evolutionary psychologists argue that aggression has developed as a human trait because of our human ancestors’ need to compete with each other for scarce resources and for mates. Critics counter that because human aggression can be so deadly, it is hard to imagine how aggression could benefit the species (Baron & Byrne, 2000). This counterargument makes two false assumptions, however. First, the fact that a behavior is not beneficial today says nothing about the environmental conditions in which it may have evolved (Tooby and Cosmides, 1990). Second, evolution through natural selection does not operate on the level of increasing the survival of the species; it operates on the level of increasing your (and your family’s) chances of survival. Aggressive behavior to drive off or eliminate competitors for scarce resources led to an increased chance of survival for individuals and their offspring, so aggression can very well be seen as an evolutionarily adaptive solution.

Today, however, we do not scare off competitors with stones or occasionally injure or kill a small band of rivals. But, we do have weapons that kill people from 100 yards away available for purchase on many street corners (in some states there are more gun dealers than McDonald’s restaurants). We also have weapons that are capable of killing thousands, or even millions, in a fraction of a second. Now that the human race has the ability to obliterate itself, we need to understand why people attack and sometimes kill each other. It is small comfort to believe that aggression was once an adaptive trait. We need to know whether biology plays a role if we want to have a chance to minimize it or the damage it can cause.

The fact that aggression appears throughout the world is important evidence that some aggressive behavior is biologically influenced. Consider war. Contrary to early research by anthropologists (Mead, 1928; 1940), it is clear that virtually all societies have had wars (Divale, 1972; Ember, 1978). There are certainly large cross-cultural differences in the frequency and type of aggression, suggesting that other factors play important roles as well (Fry, 1998), but human aggression is a fact throughout the world.

Probably the most common argument through the years that aggression is biological has been gender differences, but as you saw above, men are not necessarily more aggressive than women. Rather than arguing from gender differences, it is more useful to examine the behavior genetics evidence. Generally, the heritability of aggression appears to in the 40% – 50% range– but sometimes higher (DiLalla, 2002; Miles & Carey, 1997; Niv et al. 2013; Porsch et al. 2016); in other words, about half (or more) of the differences in aggression across people is due to differences in their genes. The situation is a little complicated, however. For example, researchers have only found significant genetic contributions when they examine aggression reported by individuals, parents, or teachers. When the researchers observe aggressive behavior in a laboratory setting (that is, by putting people in situations contrived to elicit aggression), the genetic contribution has been much lower (DiLalla, 2002).

A second, related set of biological causes is epigenetics. Recall, these are changes in phenotype, or gene expression (in this case aggressive behavior) that result from tags operating on genes without changing those genes. Researchers have found that epigenetic mechanisms can lead to increases in aggression through changes in our stress response and immune system (Waltes, Chiocchetti, & Freitag, 2015).

A third source of biological evidence is hormones. Testosterone is the hormone that has shown the closest association with aggression. You have to be very careful, though, because the common belief that “testosterone causes aggression” may be an oversimplification. Several researchers have found correlations between the amount of testosterone and aggression, but the relationships are weak and not present for all people (Berman, Gladue, & Taylor, 1993). Meta-analyses have shown weak correlations between testosterone and aggression (Book et a. 2001). There is some experimental evidence that testosterone can cause aggression, for example, in experiments that give people large doses (Pope, Kouri, & Hudson, 2000).

But, there is also evidence suggesting that aggression causes increases in testosterone. This research has not examined aggression directly but rather competition and dominance feelings. For example, when tennis players beat their opponents by a clear margin, there is an increase in testosterone (Mazur & Lamb, 1980). Even winning a simple game testing reaction time in a psychology laboratory has been associated with increased testosterone (Gladue, Boechler, & McCaul, 1989). If you are thinking that perhaps the testosterone increased first, leading to the victories, good job; that is what you should be thinking. Another team of researchers examined testosterone levels in soccer fans at the end of a game; the levels were higher in the fans of the winning team (Fielden, Lutter & Dabbs, 1998). Clearly, then, testosterone can increase as a consequence of feeling dominant. If testosterone levels increase in these situations, it seems likely that they would also increase in response to aggression.

One biological factor that has received a lot of attention is the neurotransmitter serotonin. Specifically, low serotonin has been linked to an increase in aggression. Animal studies, in which mice are bred to be high or low in aggressiveness, show marked difference in serotonin neurotransmission (Veneema et al. 2004). In humans, the relationship is quite small, however. A large meta-analysis found a weak relationship between low serotonin and higher levels of aggressiveness (Duke et al. 2013). The effect appears to be indirect, as low serotonin relieves people of inhibition, leading them to act on aggressive impulses more frequently.

Our table of supposed aggression causes culled from the internet included several foreign substances—such as drugs, steroids, or processed foods—which we also count as potential biological causes. Their direct effects would be to influence the brain or physiological systems associated with aggression. Without going through all of the candidates in detail, let us just say that alcohol is the foreign substance that has the strongest evidence of a link to aggression (Bushman & Cooper, 1990). Alcohol has been specifically noted as a contributing factor to sexual violence and spousal abuse (Stith & Farley, 1993; Testa, 2002). Alcohol makes it more difficult for the drinker to interpret social cues, which may partly explain its specific role in sexual assault (Taylor & Leonard, 1983). More generally, alcohol appears to increase aggressiveness by decreasing one’s ability to focus on the self and by making reactions to conflict more extreme (Ito, Miller, & Pollock, 1996; Steele & Southwick, 1985).

Psychological causes of aggression

The most influential psychological explanation for aggression comes from a straightforward application of social learning and cognitive social learning, which you saw in Modules 6, 17 and 19 already. Individuals can learn to be aggressive if they are rewarded for the behavior. For example, the bully who gains the respect of his peers, as well as the lunch money he took when he punched the little guy, is likely to repeat his aggressive behaviors (Bandura, 1986; Patterson et al. 1967). In addition, we can learn aggressive behaviors through observational learning.

Two important situations where we often witness aggression are at home and in the media. As we have seen spanking is associated with antisocial tendencies and aggression in children. The child watches the parent spank, and the parent gets rewarded for it (the child stops misbehaving). This is a classic setup for observational learning to occur. The media, too—television shows and movies, sporting events, even cartoons—are sometimes overwhelming sources of violent and aggressive images. You may occasionally hear on the news, that research has been inconclusive about the role of media violence in aggression. That is not true. From over decades of research, correlational, longitudinal, and most importantly, experimental, the results are consistent, conclusive, and clear. Viewing violence in the media causes aggression (Geen & Thomas, 1986; Geen, 1998; Huesmann, 2003). Researchers have also drawn similar conclusions about violent video games. Reviews of the research found evidence that violent video games cause aggression in children and adolescents (Anderson et al. 2010; Bensley and Van Eenwyk, 2001; Gentile et al. 2004).

“But hold on,” you might say. “I have heard about this, it has been in the news. They have talked a lot about the research. Violent video games do not make people aggressive. Besides, I play violent video games all the time, and I am not aggressive.” So let us address these objections. We will take care of the second one first. Every single person is just one single person. In other words, each person is a case study, and just because something is true for one case, it does not mean it is true for everyone. By now, we hope this argument sounds very familiar. It is a serious overgeneralization, and one of the most important errors to try to avoid. It is, quite simply, exactly why we have to do research, because an individual’s experience is not a valid way to discover the truth.

The second point is a bit harder to address. You will recall when we talked about the research on spanking, we talked about the myth of two equal sides. That does not seem to be going on here. The evidence on one side feels stronger, but less overwhelmingly so in this case. In other words, there is some legitimate research that finds that violent video games are not as damaging as the critics say, so the topic is still controversial. Before we get to that, though, we have to address a confusion, or more technically, a conflation (a blending or fusing of separate ideas). To illustrate the problem: in 2019, there were articles in Psychology Today, the LA Times, the NY Times, the Guardian, PBS, Time, CBSnews.com, and many other publications with virtually the same headline: “Violent video games do not cause violence.”

We never said they did.

We said they cause aggression. This is the one key difference between violence and aggression that we hinted at in the beginning of this section. Research has not really addressed the question of violent video games and violence. So it is true that there is no scientific evidence that playing violent video games causes violence. There is evidence that playing violent games causes short-term, mild increases in aggressive thoughts and aggressive behaviors. There is a possibility that these mild increases could accumulate over time to lead to longer term changes, but so far that evidence is missing (Allen, Anderson, and Bushman, 2018).

The pro-video game side has conducted meta-analyses of their own that indicate that violent video games do not lead to increases in aggression, or that the effects are very small (Ferguson, 2015). We wish we could tell you that the use of meta-analysis should make these kinds of arguments unnecessary, but it does not. Individual researchers who conduct a meta-analysis can set up their own criteria for which studies get included, and there are still options for data analyses that can, in some cases, yield different conclusions.

And we have not addressed one of the key areas of contention. Each side has been criticizing the quality of the other side’s research. For example one study that found no effect of violent video games only had their participants play the game for 15 minutes (Hilgard et al., 2019). Critics charged that this was too short to expect any effects. At the same time, some studies that do show an effect of the games on aggression have used the amount of hot-sauce the participant chooses to give to a person who dislikes spicy foods. Critics here charge that this is a poor operational definition of aggressive behavior.

To be sure, the situation is messy. But that is how scientific progress often works. Currently, we are sticking with the “short-term, mild increases in aggressive thoughts and behavior” side, but honestly, that could change in the future as more convincing evidence is produced by the other side. You might recall that this is what we called skepticism in Module 7.

Let us conclude with some less contentious ideas. In many cases, aggression is a response to an aversive condition, which is one that creates a negative emotion. The way an individual responds to aversive conditions is determined by several factors, such as genes, prior learning experiences, and the situation itself (Berkowitz, 1989; 1993). One common situational factor is violent images in the media.

The most well-known aversive condition for psychologists is frustration. Often when we become frustrated, we can become aggressive if the other factors line up. For example, video games can sometimes be frustrating, particularly when the player loses. That frustration can, in some cases, lead to aggression (Breuer, Scharkow & Quandt, 2015). Frustration is by no means the only aversive condition that can lead to aggression. Other common ones include fear, anger, pain, and uncomfortable temperature (Anderson, Deuser, & DeNeve, 1995). For example, one group of researchers examined 826 games from three seasons of major league baseball and discovered that the hotter the temperature was, the more batters were hit by pitches (Reifman, Larrick, & Fein, 1991).

When frustration was first proposed as an explanation for aggression, researchers believed that frustration always produced aggression (we now know that this is not true; for example, if there is a reasonable explanation for the frustration, people are less likely to act aggressively; Dill & Anderson, 1995). To explain how this works, they used the concept of catharsis (Dollard et al. 1939). Catharsis is the release of anger through the expression of it. In other words, in order to release one’s anger, you have to act aggressively. This idea, which really dates back to the philosopher Aristotle, has taken on a life of its own and is very commonly given as advice. If you want to get over your anger, get angry; yell at someone, kick a pillow, punch a heavy bag, etc. It is true that vigorous activity releases arousal, which can be helpful in reducing anger and aggressive impulses. It often does not work out that way, though, unless the problem that led to the anger is solved. More typically, we think of the event and get angry all over again (Caprara et al., 1994). If we choose the wrong kind of activity, catharsis does even worse. Acting aggressively through some surrogate activity, such as punching an inanimate object, tends to increase aggression instead of reducing it (Bushman, Baumeister, & Stack, 1999). And that is assuming we don’t choose to punch something harder than our hand. Broken hands are not the only practical risk. When we release anger explosively, for example by yelling at others, we may provoke them into an angry response, thus creating new problems for ourselves.

catharsis: the release of anger through the expression of it


So what is the answer to the question, “Does testosterone/pain/low serotonin/etc. cause aggression?” In very many cases, the correct answer is “yes, but. . .”

Consider an individual who was spanked as a child, watched violent cartoons and television shows as a youngster, and graduated to violent horror movies later. This individual has played many violent video games and to this day continues to watch violent movies. He was in several fights as a teenager; he won most and received a great deal of sympathy when he was attacked by a large group (and lost). It certainly sounds as if this poor soul should be a fairly aggressive individual. But we know him; he is not. He is one of the most gentle people we know. He has never once spanked his children and has not been in a fight in over 35 years. He does not drive aggressively, and we have never even heard him utter a single aggressive sentence.

What is going on? It turns out that you can never use the causes that psychologists have uncovered for a complex behavior to predict information with a high degree of confidence about any single individual. Whatever risk factors for aggression an individual may have in their background, there may be something that counteracts these. One critical factor may be the knowledge about the causes of aggression and about the relationship between anger and aggression, which can allow people to pause long enough when they have aggressive impulses to let them pass. Such is the nature of human nature. Most interesting behaviors are extremely complex with many potential causes, making it impossible to make predictions about individuals. It is only when we look at large groups that we can observe the increased likelihood that some particular risk factor leads to an increase in aggression on the average.

By the way, this very same complexity makes it extremely difficult, if not impossible, to explain any specific behavior in an individual after the fact. For example, after nearly every highly publicized mass shooting in the US, many observers are quick to blame the shooter’s feelings of alienation, or affection for “death metal” music, or fondness for violent video games as causes of their highly aggressive actions. Filmmaker Michael Moore, on the other hand, noted that the two boys who committed the mass shooting at Columbine in 1999 went bowling on the morning of their infamous act and that by the same logic (i.e., if X follows Y, Y must cause X), bowling is as likely a cause for their violence as any of the other factors commonly cited—hence, the title of his 2002 documentary, Bowling for Columbine.


  • Think about some episodes when you got angry. Can you identify positive and negative outcomes?
  • How has your opinion about aggression changed after reading this section?





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Introduction to Psychology Copyright © 2020 by Ken Gray; Elizabeth Arnott-Hill; and Or'Shaundra Benson is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.

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