The evolutionary history of the human species has influenced what we feel and when we feel our emotions. In fact, it is almost only through the lens of evolutionary history that our emotions make sense. However, this all supposes that evolution is true. While almost all biologists and the vast majority of psychologists accept the theory of evolution as true, the majority of the United States public does not accept the theory of evolution. Who’s right? Let’s have a brief look at what the theory of evolution assumes, the evidence behind evolutionary theory, and how the theory of evolution applies to psychology.
Simply put, the theory of evolution assumes three things:
1. That species change (evolve) over time.
2. There are individual differences (variations) in traits, including psychological traits, that have a genetic basis.
3. If someone survives to have more children than typical because of a genetic trait, then that trait becomes more common in later generations. This is called natural selection, and it can change how frequent a trait is in the population, causing a species to evolve.
There is a strong accumulation of evidence that the theory of evolution is right (Quammen, 2004). Much of this evidence comes from research on plants and animals, because they have shorter lifespans than do humans, allowing us to see changes in these other species over generations. Here is an overview of some of the evidence for evolution.
- Humans have caused animal and plant species to change over generations. Humans have long engaged in the domestic breeding of animals and in the breeding of plants. For example, over successive generations people bred those individual dogs that best display whatever trait people were interested in selecting. The result of this has been that we now have breeds of dog that are very different from each other (e.g., beagle vs Newfoundland dog) and from the original dogs. The same has been true for agricultural plants.
- We have observed some species change over a short time span, in response to a change in their environment (Quammen, 2004). For example, prior to the industrial revolution in England, most individuals of one particular type of moth (Peppered moths) had white wings, with a few having black wings. During the industrial revolution, factories and households poured black soot out of their chimneys. As a result, black soot was everywhere, which made it easy for birds to spot the white moths and eat them. As a consequence, the black moths were more likely to survive and reproduce, changing the general appearance of the species.
A second example of a species evolving over a relatively short time span is the bacterium C. difficile. Due to the frequent use of antibiotic drugs, and the tendency of patients to not finish taking all of their prescriptions, bacteria that had some resistance to antibiotics were more likely to survive. These were the bacteria what were increasingly able to survive and replicate. Thus, bacteria that are genetically resistance to antibiotics are much more prevalent today, than they were 40 years ago. The result of this has been a marked increase in human deaths to bacteria such as C. difficile.
- The fossil record has demonstrated not only that species change, but that over tens of thousands of years, a species can change so much that it becomes a new species (Quammen, 2004).
- The studies of the present day body structures of animals and an analysis of their DNA have independently confirmed that some animal species are more related to each other than are other animal species (Quammen, 2004).
- Complex organs in animals evolve. The study of mollusks has demonstrated how the eye has evolved from an organ that only senses light or dark, to one that functions similar to the human eye (Campbell et al., 2008).
- It is certainly possible that life evolved out of nonorganic chemicals. Around about 1950, Millar (as cited in Bronowski, 1976) in a laboratory passed electricity (representing lightning) through a container that held gases thought to be present in the early atmosphere (before life existed on earth). This was done for days. The result over time was the creation of amino acids within the container. Amino acids are the biological foundation of life.
That an evolutionary influence on emotions exists should be of no surprise. Emotion expressions, and understanding them, are adaptive and they help us to have and to raise children. For example, if someone is happy and smiles, it should be safe to approach. Expressing and understanding this expression, must have helped our early ancestors to survive and reproduce [Would you want to have sex with someone who was frowning at you? Perhaps I should ask if you are likely to get sex from someone who is frowning at you?]. If someone is angry, it signals that it may not be safe to approach. Staying away from someone who was angry helped our early ancestors stay in the gene pool; those who did not stay away from others who were very angry at them . . . There is no question that feeling love towards a partner increases the likelihood of having sex and producing children, while feeling love towards one’s children means that the children are more likely to survive to get the chance to reproduce.
Charles Darwin believed that many, but not all, emotional expressions are innate in humans. He used 4 kinds of evidence to argue that emotional expressions are not learned: (1) some expressions appear in similar forms in both lower animals and humans, (2) emotional expressions development early in infancy, (3) similar expressions are evident in both the blind and the sighted, and (4) that emotional expressions are universal: similar expressions occurring across different cultures. The evidence is generally supportive of Darwin’s position that some emotions are innate.
In Darwin’s book "The expression of emotions in man and animals" (1872), he hypothesised a basic continuity of emotional expressions from lower animals to humans. He suggested that the baring of the fangs of the dog or wolf is related to the sneer of the human adult. He noted that the flushing of the face during anger is seen in humans almost regardless of race, and is also seen in certain species of monkeys. In fear, a variety of animals make themselves try to look bigger. For example, in cats, they arch their backs and their hairs puff out. In angry humans, they expand their chest, thrust their head forwards, stand erect, and sometimes their body hair will stand on end.
Perhaps the most interesting studies (Ginsburg, 1977; Ginsburg, Pollman, & Wauson, 1977) in this vein were of aggression and altruism (helping behavior) in school children. These studies found that playground fights would end when one child displayed submissive nonverbal behaviors. These submissive behaviors were head bowing, shoulder slumping, kneeling, lying motionless on the ground, and shoe tying. It was suggested (Ginsburg et al., 1977) that this is similar to wolves fighting wherein the submissive gesturing of exposing the throat ends the wolves' fight. What was also found with the school children was that if the aggressor failed to stop fighting when the other child nonverbally signalled submission, then bystanders would step in to stop the fight (Ginsburg, 1977). However, while children (4th and 5th graders) watching video tapes of the fights could correctly predict when the fight would end, they were unable to verbally explain why they knew when the fight would stop. Thus, it would appear that these submissive behaviours are triggered and responded to at an unconscious level in humans.
Evidence in support of Darwin’s observation that emotional expressions develop early in infancy is a little more complex. Infants’ abilities to send and receive emotional communications are not at all well developed at birth, but instead emerge as the brain develops. At birth, the infant brain only weights about 25% of its eventual adult weight (Bjorklund, 2005). Similarly, infants’ visual systems are quite immature at birth. Until 6 months of age infants’ vision is fuzzy and they cannot focus well. Due to these visual limitations, it is only at about 3 months of age that they learn their mother’s face, the face they have seen pretty constantly. Further, it is only at about 6 months of age that they can tell the difference between familiar faces and strangers’ faces. It is at this point (6 months), now equipped with a well developed visual system, that they can distinguish several different emotions, and can tell the difference between mild versus intense emotions on the expressions of others. Keeping these limitations of the newborn’s visual system in mind, there is evidence for an early biological component in the emotions of: happiness, surprise, anger, sadness, disgust, and fear (LaFreniere, 2000). These emotions are all evident in the first year of life, although they mature through experience with others and feedback from others. Other emotions (such as shame, guilt, or jealousy) emerge later during development (LaFreniere, 2000).
Darwin had also argued that some emotions were innate because similar expressions are evident in both the blind and the sighted. Again, there is good evidence for this position. There is compelling evidence that facial expressions of emotion are not simply a product observational learning (Matsumoto & Willingham, 2009), as Darwin had reported. Although there have only been 10 studies of the spontaneous expressions of the congenitally blind, all 10 found that blind individuals produced the same emotional expressions as sighted individuals (Matsumoto & Willingham, 2009). Indeed, both sighted and nonsighted Olympic athletes display similar emotional expressions to winning or not winning (Matsumoto & Willingham, 2009). Thus, studies of the congenitally blind provide evidence for a strong genetic component for emotional expression, at least for the emotions of happiness (to winning) and sadness (to losing). Interestingly, while the congenitally blind spontaneously display these emotions, they cannot consciously produce them on demand.
There is good evidence that emotional expressions are universal, although not everyone agrees. Although the universality of emotional expressions was studied in the late 1800s and early 1900s, the now classic evidence comes from a later study by Ekman and Friesan (1971). Ekman and Friesan tried to answer whether particular emotion expressions are understood the same way by people from all cultures, by seeing if people who had almost no contact with the modern Western society would be able to correctly read the facial expressions of Westerners. They focused on members of an isolated tribe in the South East Highlands of New Guinea (a large island in the South Pacific) who had minimal contact with Westerners and no contact with the Western media. Participants from the tribe were read a short story that involved either happiness, sadness, anger, disgust, surprise, or fear. The stories were chosen to be meaningful to the members of the tribe. For example, the sad story was that a child had died. After hearing the story, participants chose which of three pictures of different facial expressions best described the emotion conveyed by the story. The people who posed the emotions in the pictures were all Westerners. The results were that for 20 of 23 sets of three pictures, members of the tribe chose the correct picture between 65-100% of the time, significantly greater than chance. Because these tribe members who had minimal contact with Westerns could correctly interpret the facial expression of Westerners, this was taken as evidence for the universality of emotional expressions: that people everywhere exhibit and understood the same facial expressions of happiness, sadness, anger, disgust, surprise, and fear.
Not everyone believes that emotions are universal. In a major review article, Russell (1994) disputed the "fact" that emotions are universally recognized from facial expressions. Russell pointed out that in research done in the 1920s, different subjects used different emotional labels to describe the same expression. However, later researchers overcame this problem by grouping related emotions (e.g., wonder, amazement, and surprise). Nevertheless, Russell correctly pointed out that most people find it difficult to identify real time emotions if the contextual cues have been removed.
In Russell's own review of studies that have been similar to the Ekman and Friesan (1971) study, Russell found a difference between the performance of Western participants and that of African participants. When looking at how well participants categorize facial expressions from another culture as either happy, surprise, sadness, fear, disgust, or anger, Western participants would correctly categorize a particular facial expression about 80% of the time, while African subjects would correctly categorize a given facial expression about 50% of the time. Japanese subjects show a similar pattern to the African subjects for the emotions of fear, disgust, and anger. Russell found the data involving the recognition of facial expressions by isolated tribes unconvincing. He pointed out that the tribes had some contact with Westerners and suggests that some experimenter basis may have affected the results.
Recognition Scores From Eight Studies With Literate Subjects.
Reprinted From Russell (1994), publisher: APA.
Note. Izard's (1971) term for "sadness" was distress, but it was defined as synonymous with sadness. " Ekman, Sorenson, and Friesen (1969). "Izard (1971). ° Ekman (1972). d Niit & Valsiner (1977). 'Boucher and Carlson (1980); figures given are unweighted average across two stimulus sets. fDucci, Arcuri, W/Georgis, and Sineshaw (1982). 8 McAndrew (1986). " Ekman et al. (1987).
Russell noted that highly educated people are more likely to recognize facial expressions than are people with little education. He also noted that facial judgments tend to be relative; a judgment of a single face tends to depend on what other faces have been shown.
In a rebuttal, Ekman (1994) strongly disagreed with Russell's assessment of the literature. Ekman believed that there are some universals and some cultural differences in emotional expression. This indeed is the case. Ekman pointed out that for the data that Russell presented, only 14% of the variance directly related to culture, and only 3% of the variance related to the interaction between culture and emotion. Thus, the vast majority of people’s judgments (83% of the variance) was associated with correctly categorizing the emotional facial expressions of someone from another culture. It should also be noted that if people were only performing at a chance level on this task, they would only be correct about 17% of the time if six emotions was displayed and at 33% if three emotions were displaced. Non-Westerners were clearly performing better than chance. The only possible exception was the “African” sample’s accuracy for sadness, but this was not the case for the Ethiopian sample.
As for cultural specifics, Ekman cited one of his earlier studies (Ekman, 1972) which involved videotaping the spontaneous facial expressions of Japanese and Americans in a laboratory setting while they watched a stressful film of a ritual that involved bodily mutilation. Ekman (1972) found similarity in the spontaneous facial expressions of distress displayed by both Japanese and Americans, particularly in the display of disgust. Displays of sadness were also frequent in the two groups (but twice as likely among the Japanese).
Every researcher seems to agree that the expression of happiness is interpreted the same way by people of every culture. Every researcher agrees that culture can influence when we feel particular emotions, and the degree to which we mask emotions, trying not to reveal what we are actually feeling – something we all do at times (e.g., when talking to potential mates, when talking to our bosses, etc.). What now is also clear based on comparative (across species) research, developmental research, studies of the congenitally blind, and cross-cultural research is that there is a small set of emotions that all normal people experience. We all experience these emotions because (as we will see later) evolution has given us particular biological structures that give rise to these emotions.
What are the basic emotions?
Several researchers have tended to see emotional experience as simply composed of two underlying psychological dimensions: (a) how pleasant or unpleasant something is, and (b) how strongly this is felt. However, many others make the assumption that evolution has endowed humans with a small number of basic (or primary or fundamental) emotions. These evolution-influenced researchers of emotions (e.g., Plutchik, 1994) often assume that all other emotions are mixtures or blends of the primary emotions. From this perspective, one needs to identify the basic emotions and explain what other emotions are derived from which blends.
While critics of an evolutionary perspective (e.g., Turner & Ortony, 1992 - who see emotion as dependent on cognition) argue that there is no satisfactory criterion for "basicness," there are criteria that can be applied to identify basic emotions. To identify basic emotions, researchers can: (a) use factor-analysis (Plutchik, 1994). This involves looking for high intercorrelations within a set (or better yet, several sets) of data, perhaps ratings of emotions. The assumption is that if two or more emotions are always highly correlated then a single basic emotion must underlie them. (b) Look for separate physiological systems (Ekman, 1992; Izard, 1992) for each basic emotion. (c) Examine whether facial expressions are the same for two "different" emotions (Ekman, 1992). If the facial expressions are the same, then they are more likely to be the same emotion. (d) Conduct a developmental study of which emotions we are born with, and which emotions are learned. These four approaches could be used as criteria for "basicness".
Let's see what others have proposed as basic emotions. Ekman (1992) proposed that happiness, surprise, fear, sadness, anger, disgust (and maybe contempt) are the basic emotions. He has presented evidence (Ekman, 1994; Ekman & Friesan, 1971) that these 6 or 7 emotions have unique facial expressions and that these facial expressions are universally recognized. That is, no matter what cultural or racial group, everyone interprets the unique facial expressions of these emotions in the same way.
Along with his colleagues, Ekman also reports different autonomic nervous system activity for: anger, fear, sadness, and disgust. Ekman argues that happiness and contempt do not have distinct ANS patterns because it would not have helped humans’ evolutionary survival.
Izard (2007) proposed that interest, joy/happiness, fear, sadness, anger, and disgust, are basic emotions. He believed that love, depression, and anxiety are the result of some combination of these basic emotions. Izard (2007) thought that each basic emotion is a gestalt composed of particular neural networks, nonverbal-expressive behaviors (i.e., facial expressions and body language), and feelings/motivations. Thus, each basic emotion is associated with a particular combination of facial responses that correspond to a particular subcortical program. Emotions pre-empt consciousness and tend to trigger a particular response strategy. People may learn particular cues that cause an emotion, but they do not learn the basic emotion itself. For Izard (1993), higher cognition is not a necessary condition to provoke emotions, but higher cognition is involved in our experiencing the range of emotions beyond the basic ones.
An example of emotion without cognition would be free-floating anxiety, which is when an individual is often anxious but without any reason or cause that the individual can identify.
Thus, to summarize Izard's view fundamental emotions have: a specific neural basis, a specific facial expression, a distinct feeling, an origin in evolutionary-biological processes, and a motivating property that serves adaptive functions.
Robert Plutchik is both a clinician and a researcher in emotions. Plutchik (1994) proposed that anticipation, joy, trust, fear, surprise, sadness, disgust, and anger are basic emotions. Plutchik has described how each of these basic emotions can vary in strength, resulting in a different emotion (see Figure 1). Specifically, the emotion that corresponds to the weaker and stronger expression of each basic emotion is as follows:
|| More intense|
Furthermore, he suggested that depression, mania, and paranoia are extreme versions of, respectively, sadness, joy, and disgust.
Plutchik also specified what additional (secondary) emotions result from the blending of basic emotions. Specifically:
||Elemental basic emotions|
||= joy + trust|
||= trust + fear|
||= fear + surprise |
||= surprise + sadness|
||= sadness + disgust|
||= disgust + anger|
||= anger + anticipation|
||= anticipation + joy|
||= joy + fear |
Plutchik’s primary emotions (plus their variations in intensity) and secondary emotions are illustrated in Plutchik’s color wheel (see Figure 1). The circle defines the degree of similarity of emotions. Note that the emotions line up in opposites.
Figure 1. The Relationship of Emotions in Plutchik’s Psychoevolutionary Theory of Emotions. (Reprinted from Wikipedia.)
Plutchik (1994) believed that emotions increase an individual's chance of survival by priming for, or initiating, appropriate behaviours for the situation at hand. Genes indirectly effect emotions by providing a blueprint for the structure and functioning of important biological components (such as the autonomic nervous system and the brain), which in turn influence behaviour. Plutchik also believed that our emotional reactions are effected by how we cognitively evaluate events. We decide whether events are of significance to us, and if so then physiological changes occur that can create urges that initiate, or suppress, particular behaviours.
There is substantial overlap in the lists of basic emotions proposed by Ekman, Izard, and Plutchik. They agree that happiness, fear, sadness, anger, and disgust (and perhaps surprise) are basic emotions. Others have suggested that love and pride are also basic emotions, but there is not currently general agreement on whether these are indeed basic emotions.
More than other researchers, Plutchik has most explicitly suggested which combination of basic emotions form which secondary emotions. However, We need to keep in mind that while some emotions (e.g., jealousy) are indeed closely linked to basic emotions (e.g., fear and anger in the case of jealousy), there have been few studies on whether basic emotions are indeed “elements” of other (secondary) emotions (Campos et al., 2010).
If basic emotions are hardwired into us, then they must be programmed into our biological system, likely our autonomic nervous system and the brain. While the autonomic nervous system and the brain are the major biological substrates of emotions, other biological systems such as the endocrine system (hormones) and even the respiratory system, may also play a role.
The autonomic nervous system directly interacts with our organs, muscles, and hormonal glans within our body. Because of its influence on our body, the autonomic nervous system is a key regulator of our feelings. The autonomic nervous system can be subdivided into two components: (a) the sympathetic nervous system and (b) the parasympathetic nervous system. Only one of these systems can be activated at a given time. The sympathetic nervous system has been molded by our evolutionary history to prepare us to fight, flee, or mate.
Let us imagine that you are on a dock on a lake with someone who you find really attractive. You are both sitting close to each other on the dock. There is not another soul around. It is a beautiful, warm day with not a cloud in the sky. You lean in towards the other person while he or she leans towards you. So what happens to your body? Well, the sympathetic nervous system is activated and it causes your heart rate to increase (so you can pump blood to muscles where it will be needed), your breathing rate to increase (so you will have more oxygen in the blood for exertion); your digestive system to shut down (so that you will have more blood for other organs or muscles); your muscles to tense (preparing you for action), causing hair to stand up on your skin (which people sometimes refer to as “goose bumps”); your pupil in each eye to dilate – widen (sharpening your vision); and adrenaline to be released into your bloodstream (providing additional energy for action). So, the sympathetic nervous system, through this coordinated bodily response primes us for action. To quite a large extent, this bodily response is the same whether we are getting ready to run from a predator, to fight for our life, or when we are forced to listen to our boss yell at us. So, it should be no surprise that a variety of emotions (e.g., anger, fear, and surprise) are linked with the activity of the sympathetic nervous system. An exception to this is sadness. Sadness is linked with activation of the parasympathetic nervous system. The parasympathetic nervous system is linked with relaxation, rather that preparing for action. When we are sad, we are less likely to feel like doing things.
The nature of the link between emotions and the autonomic nervous system has long been a matter of debate. In the late 1800's, William James and Carl Lange offered an alternative to our common sense understanding of emotions. Common sense tells us that when we see an event, we have some feeling (e.g., sadness) and this feeling then results in physiological reactions (e.g., crying). However, James and Lange reversed these events. They believed that the physiological reactions occurred first and then resulted in the subjective feeling. Thus, they believed that we are sad because we are crying. Furthermore, James perceived that the physiological reactions occurred from direct perception (that is, with no conscious or perhaps even cognitive component). However, a more recent clarification (Ellsworth, 1994) of James writings has suggested that James’ theory was actually more nuanced than most people realized. According to this clarification, James suggested that a stimulus may cause an interpretation on our part (an appraisal) about its meaning, which in turn causes a bodily response, which in turn triggers a feeling (i.e., stimulus -> interpretation -> bodily response ->affect). Most people have, perhaps mistakenly, taken the James-Lange theory to be: Stimulus -> bodily response -> affect.
James believed that his theory applied only to "coarser" emotions, such as grief, fear, rage, and love. The physiological reactions that he referred to were autonomic, hormonal, and muscular.
James suggested that two types of evidence support his theory. First, he said it's impossible to imagine an emotion taking place separate from a bodily experience. Second, people can sometimes report feelings (such as anxiety, sadness, or happiness) without knowing why. So, James' evidence was often anecdotal.
For Lange, a physiologist, emotions were specifically the result of the functioning of the cardiovascular system. Emotional structures were generally seen by Lange as subcortical [unconscious].
In opposition to the James-Lange theory, W. B. Cannon (in the 1920's) did not believe that emotions could be the result of a perception of unique physiological changes (Hothersall, 1995). Cannon believed that the autonomic nervous system gave basically the same response no matter what it was that the individual felt. In addition, the physiological system was too slow to react, as well as not having enough diversity in reactions, to cause the diversity of emotional reactions. Cannon, unlike James, believed that specific brain structures were probably involved in emotions.
So, were James and Lange correct, or was Cannon correct? There is some modern empirical evidence that is consistent with the James-Lange theory (but Cannon was correct that specific brain structures affect particular emotions). There are distinct physiological differences associated with different emotions (Critchley, 2009; Stephens, Christie, & Friedman, 2010). For example, heart rate increases when someone sees a happy or disgusted faces while heart rate decreases when someone sees a sad or angry face (Critchley, 2009). However, the physiological differences in emotions are apparently small, while the similarity in autonomic responses across emotions is large. And, it seems that not everyone shows physiological differences across emotions. Physiological variables such as heart rate may also vary with the situation even when the specific emotion is held constant. So, the relationship between autonomic responses and emotions is complex. Still, Stephens et al. (2010) were able to use differences in autonomic responses to correctly classify experimentally induced emotions (i.e., anger, fear, sadness, surprise, amusement, or contentment) 44.6% of the time.
Another surprising line of evidence that is consistent with the James-Lange theory comes from facial expressions. The facial feedback hypothesis holds that particular muscle activation that underlie our facial expressions cause us to feel specific emotions. It is kind of a “smile and you will feel happy, frown and you will feel sad” theory. What surprises most people is that the evidence suggests that this is indeed true, although the effect is of a small magnitude. When people are asked to hold a pencil in their mouth (across the corners of their mouth) in a way that causes them to smile, they are slightly happier then when they hold a pencil in the mouth (with the pencil pointing straight out) in a way that causes them not to smile (Soussignan, 2002). Posing an emotional facial expression, like a smile or a frown, even when people do not realize they are doing so, actually causes a small increase in their emotional experience. Similarly, having people not move their facial muscles decreases their emotional response, even when they are unable to guess the purpose of the study (Davis, Senghas, & Ochsner, 2009). People who have Botox injectioned into their face, which paralyzes some muscle movement, experience a slight decrease in the strength of their positive emotional response to a selected video clip (Davis,Senghas, Brandt, & Ochsner, 2010). This was in comparison to those in a control group who received injections of a substance that was a filler that did not affect muscle movement (Davis et al., 2010). However, the Botox group did not experience an expected decrease in the magnitude of their negative feelings to a video clip with negative emotional content, which might suggest a weak or inconsistent effect.
A variant of facial feedback is facial mimicry. When we watch actors or listen to others talking to us, we often mimic the facial expression of the speaker. When we do this, it can trigger an emotion within us that corresponds to the speaker’s facial expression (Stel & van Knippenberg, 2008). Furthermore, facial mimicry often happens without our conscious awareness, and can influence autonomic responses such as heart rate (McIntosh, 1996).
An intriguing question is how exactly does making a facial expression cause us to feel a particular emotion? A partial explanation is given by the vascular theory of emotional efference (McIntosh, Zajonc, Vig., & Emerick, 1997; Zajonc, Murphy, & Inglehart, 1989). This theory suggests that muscle movements of the face may directly or indirectly (by regulating air intake through the nose) influence the temperature of blood going to the brain and thereby affects brain functioning. Biochemical processes are generally temperature sensitive (Zajonc et al., 1989). The theory assumes that decreased brain temperature causes pleasurable emotions.
Zajonc et al. (1989) points out that the carotid artery interacts with the cavernous sinus (a vein which comes from the face) just before the carotid enters the hypothalamus. Thus, the cavernous sinus (from the face) can cool the carotid, which in turn influences the temperature of the hypothalamus. So, what Zajonc is proposing is a mechanism whereby the physical component can cause changes in one's subjective emotion, with minimal cognitive processing.
In support of the vascular theory of emotional efference, it has been found that: (a) changing facial muscles effects the amount of air breathed, and correlates with an indirect measure of brain temperature; and (b) inhibiting how much air can be breathed causes negative emotions, also correlating with an indirect measure of brain temperature (McIntosh et al., 1997). It is also well established that aerobic exercise (which increases breathing) can be successful in alleviating depression. However, the vascular theory of emotional efference can only be part of the explanation for how facial expressions effect emotions (McIntosh et al., 1997). It provides an explanation for feeling happy versus feeling sad, but it does not explain how facial expressions of any of the other basic emotions results in their associated feelings.
One line of evidence that appears not to support the James-Lange theory comes from Paraplegics. These people have reduced information coming from the autonomic nervous system to the brain. If the body triggers emotional feelings as James suggested, then people with reduced information from their body (i.e., spinal cord patients) should experience emotions less strongly than do other people. The findings from these types of studies have been mixed, with some reporting reduced emotions for individuals after becoming paraplegic, while other studies have reported an increase in emotional experience for individuals after becoming paraplegic. Recent studies (Cobos, Sánchez, Pérez, & Vila, 2004; Dickson, Allan, & O’Carroll, 2008) have generally found that the subjective emotional experience of patients, after their spinal cord damage, has not changed, or has increased, especially for sadness. In one study (Cobos et al., 2004) that had spinal cord patients rate their reactions to individual emotion provoking stimuli, paraplegics did not differ from control subjects in feeling joy, love, fear, and anger, but felt heightened levels of sadness.
So, there appears to be support for the James-Lange theory from some lines of research, but not from others. We know that the autonomic nervous system is involved in our perception of emotions, and that feedback from at least facial muscles influences emotional feeling. Does this affect how clinical and counselling psychology should be practiced? Perhaps it should. It should remind us that the reaction of the body should not be forgotten; that in addition to changing people’s maladaptive thinking, we should also be teaching people how to turn off or turn on their sympathetic nervous systems, which would sometimes include teaching people how to relax their facial muscles.
Excitation transfer theory
Excitation transfer theory (Zillmann & Bryant, 1974) describes how we do not always consciously understand the activity of our sympathetic nervous system, and how this can heighten our emotional experience. This theory assumes two things (Leventhal & Tomarken, 1986). First, it assumes that activity of the sympathetic nervous system does not just suddenly stop. Rather, sympathetic nervous system arousal gradually reduces over time. Second, it assumes that people often mistakenly think that their feeling (partially from sympathetic arousal) only results from one cause, when this is not always true. Thus, the theory predicts that “left over” arousal from a previous situation can combine with arousal from a later situation resulting in an increased emotional experience that the individual only attributes to the later situation. This can actually explain why make-up sex can be so electric: left over arousal from arguing can combine with sexual arousal and this combined arousal is only attributed to the sex. Excitation transfer theory also explains why horror movies usually have some comic scenes embedded within the film: left over arousal from the comedy combines with the arousal from a later scary scene, making us feel even more scared.
Leventhal and Tomarken (1986) noted that the results of a number of studies have provided evidence supporting excitation transfer theory. This evidence included findings that (a) physical exercise can heighten later feelings of anger, (b) physical exercise can heighten later feelings of sexual excitement, (c) sexual excitement can heighten later feelings of aggression, (d) sexual excitement can heighten subsequent enjoyment of music, and (d) excitement from humour can heighten later feelings of aggression. So, the transfer of arousal can be between very different emotions.
Excitation transfer theory might partly explain why two reality television show dating contestants (Jake and Vienna), who were both very scared of heights, seemingly become more strongly attracted to each other after being tied together to a single bungee cord and jumped from a tall bridge over a rock canyon, only to then share a passionate kiss as they hung upside down tied to their bungee cord. Presumably, the very strong fear induced arousal from their jump from the bridge combined with the arousal from their kiss, making the experience of that kiss even more passionate. Interestingly, the effects of excitation transfer are lessened when the individual realizes the causal linkage to the earlier event (Leventhal & Tomarken, 1986).
Although the body plays an important role in emotional experience, so does the brain. It is in the brain that we evaluate the emotional significance of people and situations, and it is in the brain where we decide how to react. When emotional, versus non-emotional, stimuli are presented in a controlled laboratory setting, there is enhanced sensory processing in the occipitotemporal area (D’Hondt et al., 2010). Subsequently, emotional stimuli may cause activity in the amygdala and activity in the medial prefrontal cortices (D’Hondt et al., 2010). However, after the sensory processing, different areas of the brain tend to be involved in processing different emotions (see Table 2). This is evidence that emotions are more complex than when described (as recommended by some researchers) by simply two dimensions: (a) degree of pleasantness, and (b) degree of arousal. Rather, there are separate (e.g., basic) emotions that are to some extent processed by different areas of the brain (Buck, 1999; Vytal & Hamann, 2010).
Diagram of the brain with the green region indicating the prefrontal cortex. From bungelab.berkeley.edu (Sept. 1, 2010).
A recent meta-analysis (Vytal & Hamann, 2010) of 83 human neuroimaging studies found that basic emotions consistently have distinct neural processing centers, but with some overlap in the activated neural centers. The study utilized results from studies that either induced emotions or had participants view emotional facial expressions or emotion provoking pictures. The meta-analytic technique used a quantitative spatial analysis of the previous findings to average the results and find distinct clusters (locations) of increased activity in the brain. The results of the meta-analysis are as follows. Happiness triggered the greatest activity in the right superior temporal gyrus, with 8 other brain locations of activation. Sadness triggered the greatest activity in the left medial frontal gyrus, with 34 other brain locations of activation. Anger triggered the greatest activity in the left inferior frontal gyrus, with 13 other brain locations of activation. Fear triggered the greatest activity in the left amygdala, with 11 other brain locations of activation. Finally, disgust triggered the greatest activity in the right insula and in the right inferior frontal gyrus, with 14 other brain locations of activation.
Diagram of major brain gyri from Wikipedia (Sept. 1, 2010).
The partial independence of different brain areas in processing different emotions can be seen when people are exclusively presented with pictures of faces showing one of several emotions. In a meta-analysis (Fusar-Poli et al., 2009) of 105 studies (totaling 1600 participants) using this procedure with each study utilizing functional magnetic resonance imaging techniques, it was found that the brain responded differently to disgusted, happy, sad, angry, and fearful faces compared with neutral faces. For both disgusted and angry faces, a part of the outer cortex called the insula was particularly active, but much more active (and active in both right and left hemispheres) for disgusted faces. The thalamus also was particularly active for disgusted faces. For the angry faces, the insula was active only in the left hemisphere, along with part of the occipital cortex being particularly active.
Brain Regions Associated with Conscious Emotional Processing.
right superior temporal gyrusa
||left medial frontal gyrusa |
lingual gyrusb (cortex)
anterior cingulated (cortex)
dorsal preoptic area
||left amygdalab |
medial frontal gyrusa (cortex)
||right insulaa,d |
right inferior frontal gyrusa
medial frontal cortexe
||left inferior frontal gyrusa|
Note. aVytal & Hamann (2010). bFusar-Poli et al. (2009). cDuan, Dai, Gong, & Chen (2010). dIbañez, Gleichgerrcht, & Manes (2010). eBasile et al. (2011). fBuck (1999).
Diagram from Wikipedia showing the insula, (Jan. 23, 2007). Original from Gray’s Anatomy.
Diagram from Wikipedia (Nov. 18, 2008).
For both fearful and happy faces, the amygdala was active in both hemispheres, but much more for fearful faces. Happy faces also activated a part of the cortex involved in arousal to emotional sights (Fusar-Poli et al., 2009). In contrast, fearful faces actived a different part of the cortex (medial frontal gyrus), one that is involved with inhibiting emotion and conscious monitoring of emotions before making a decision (Fusar-Poli et al., 2009). Viewing sad faces evoked activation in the amygdala and a part of the cortex (lingual gyrus) in the back of the brain.
Diagram of cortical areas from Wikipedia. Author: Hagmann P, Cammoun L, Gigandet X, Meuli R, Honey CJ, et al. (Nov. 29, 2009).
Although the amygala is involved in processing fearful, happy, and sad pictures, it is different parts of the amygdala involved in processing these three emotions (Fusar-Poli et al., 2009). We should also note that there is commonality in brain functioning for various emotions. The cerebellum is active in the processing of disgusted, happy, sad, angry, and fearful faces (Fusar-Poli et al., 2009). Perhaps this reflects some general arousal and/or mimicry to emotional faces.
Other evidence is also consistent with basic emotions corresponding to separate neural circuits, but with some overlap. For example, a variety of types of patients who have had damage to the insula have difficulty in recognizing disgust in others and in experiencing disgust themselves (Ibañez, Gleichgerrcht, & Manes, 2010). However, this area of the cortex is not exclusive to disgust, but also appears to play a role in major depression (Ibañez et al., 2010). Trait anxiety has been linked to increased amygdala reactivity (Hariri, 2009), and sadness has been linked to a neural circuit involving the anterior cingulate, the ventral septal, the dorsal preoptic area.
Lust is often classified as a motivation rather than as an emotion. However, it has been suggested (Buck, 1999) that emotion and motivation are part of a common system. If we accept this suggestion, then it is worth noting that lust (along with submission, attachment, and playfulness) is part of a separate neural circuit composed of the septal area, thalamocingulate influence, and the front of the hypothalamus (Buck, 1999). The septal area is part of the cingulate gyrus in front of the thalamus. The septal area is a pleasure center in the brain and rats will continually press a bar if an electrical stimulation is then delivered to the septal area.
The neural processing of guilt may depend on what is causing us to feel guilty. Feeling guilty over a deviation from one’s values is associated with increased processing in the cingulated gyrus, medial frontal coxtex, and insula (Basile et al., 2011). On the other hand, feeling guilty over personal interactions does not involve increased activation in the insula (Basile et al., 2011). Perhaps the former type of guilt involves an element of self disgust?
It is important to remember the forest (the implication) and not just the individual trees (the various brain circuits) when looking at the brain circuits associated with emotions. The finding that there are different brain circuits associated with particular emotions is consistent with an evolutionary approach to emotions. We are biologically hardwired to experience the basic emotions.
Unconscious brain processing
Based on animal research, LeDoux suggested that there are two separate neural circuits involved in experiencing fear: a subcortical (unconscious) and a cortical (conscious) circuit (LeDoux, 1994). In the subcortical circuit visual information is first processed by the thalmus with information then directly passed to the amygdala. The amygdala will then send a danger signal to the autonomic nervous system. The second pathway involves information being passed from the thalmus to the visual cortex. In the visual cortex more sophisticated visual processing takes place, so that you can better understand what the stimulus is (e.g., a snake or a stick). This "extra" processing takes more time. If it is something to be afraid of, that information is relayed from the visual cortex to the amygdala. The subcortical and cortical pathways may both be working at the same time, but a quick fear reaction may first be felt as the result of the subcortical (automatic\unconscious) circuit, and it may take a few moments until the individual realizes why it is that he or she feels afraid.
Brain imaging research has found similar separate conscious and unconscious circuits in people. While the conscious processing of a fearful face is associated with increased processing in the left amygdala, dorsal anterior cingulate, and medial prefrontal cortex, subliminal exposure to a fearful face is associated with increased activity in the right amygdala and ventral anterior cingulate areas (Williams et al., 2006). While conscious processing of a surprised face is generally associated with increased processing in the parahippocampal gyrus, subliminal exposure to a surprised face is associated with increased activity not only in the parahippocampal gyrus, but also in the fusiform gyrus, the right thalamus, and the right amygdala (Duan, Dai, Gong, & Chen, 2010). Thus, in people there are clearly separate neural pathways for conscious and unconscious processing. It is no surprise that we sometimes experience an emotion before we know why. The brain automatically (unconsciously) processes information to decide whether it is personally relevant to us or not.
The prefrontal cortex has an important role in emotional regulation. The prefrontal cortex is involved when we try to feel better by rethinking the meaning of an event (reappraisal) or by trying to think of the emotion provoking situation in a more emotionally detached manner (Koenigsberg et al., 2010). There may be a variety of cortical regions involved when we directly experience or think about emotional situations. For example, when we try to distance ourself (i.e., trying to be a detached observer) from emotional social pictures, the following brain regions are active: dorsal anterior cingulate; medial and lateral prefrontal cortex; precuneus; posterior cingulate cortex; intraparietal, superior and middle temporal gyri (Koenigsberg et al., 2010). Another part of the cortex, the orbitalfrontal cortex, has direct connections with the hypothalmus, amygdala, and brainstem, and automatically regulates the duration, frequency, and intensity of positive and negative emotional states. Of major clinical relevance, patients with posttraumatic stress disorder show decreased prefrontal cortical activity when viewing negative pictures compared to control subjects (Luan, Briton, Taylor, Fig, & Liberzon, 2006). Thus, although LeDoux (1994) said that it is quite difficult to get rid of emotional memories and that suppression of relatively permanent negative emotional memories may be the best clinical approach, this is often difficult to achieve.
Hemispheric specialization of emotions.
There is evidence that the right hemisphere is more active in the processing of negative emotions while the left hemisphere is more active in the processing of positive emotions (Balconi & Mazza, 2010; Hecht, 2010). EEG recordings have found increased left frontal cortical activity when viewing happy faces, increased right frontal cortical activity when viewing fearful or angry or surprised faces, but no cortical differences when viewing sad or neutral faces (Balconi & Mazza, 2010). In people who are depressed, there tends to be increased neural activity in the right hemisphere and decreased neural activity in the left hemisphere (Hecht, 2010). Damage to the left (more positive emotions) hemisphere is associated with depressed mood while damage to the right (more negative emotions) hemisphere is associated with elevated mood (Hecht, 2010). Nevertheless, laterality in emotional processing appears to be neither complete nor simple. Recent meta-analyses (Fusar-Poli et al., 2010; Vytal & Hamann, 2010) of FMRI studies have found particular regions of the left hemisphere involved in the processing of sadness, and anger, as well as a region of the right hemisphere involved in the processing of happiness. Perhaps it is best to suggest that there is somewhat more processing in the right cortical hemisphere for negative emotions and somewhat more processing in the left cortical hemisphere for negative emotions.
The hemispheric differences in the processing of emotional words are consistent with the differences in the processing of faces. Wexler, Warrenburg, Schwartz, and Janer (1992) used a dichotic listening task where two words were presented at the same time, one to each ear. In each word pair, the words differed from each other only in their initial consonant. One of the words was emotionally neutral while the other was either emotionally positive or emotionally negative (hug, tug/died, bide). When these pairs are presented, people consciously experience only one of the words.
Wexler et al. (1992) measured EEG and EMG activity when the words were presented. EMG measures electrical activity from particular muscles in the face; certain facial muscles are associated with particular facial expressions and, thus, with particular emotions. For example, in conjunction with negative emotions, there is activity in the corrugator muscle (that furrow the brow during frowning) and a decrease in right frontal alpha (EEG) activity. In conjunction with positive emotions, there is an increase in zygomatic muscle activity (that raise the corner of the mouth in a smile), and a decrease in left frontal alpha activity.
What they found was that frontal EEG alpha activation for emotional words that were not consciously processed showed interesting hemisphere effects. Here, activation tended to be left side dominant for positive emotional words, but right hemisphere dominant for negative emotional words. They found the right hemisphere more active in unconscious affect trials and the left hemisphere more active in conscious affect trials.
Support for the finding of right hemisphere dominance in unconscious processing also comes from a study by Ladavas, Cimatti, Del Pesce, and Tuozzi (1993). They studied the processing of emotional stimuli in a single split-brain patient in whom the two hemispheres has been completely disconnected through surgery. Their subject was a right-hemisphere dominant, 40-year-old, male. He was shown slides containing either neutral, sexual, or disgusting (e.g., rotten food) content. These stimuli were presented either above or below visual threshold, and were presented to the left or right hemisphere. The subject's task on each trial was to first identify the emotional category of the stimuli, and second, to report the content of the slide.
They found that even for the subliminally presented slides the patient could correctly identify the emotional category of the slides, but that he could not identify the content of the slides, either through verbal identification or through a forced-choice recognition task. Heart rate data taken during the experiment consistently indicated that when the patient was presented subliminal emotional information there were changes in heart rate for both sexual and disgusting material presented to the right hemisphere, but no heart rate changes for material presented to the left hemisphere. When presented stimuli slow enough to be consciously processed, both hemispheres processed the information and caused increases in heart rate for the sexual and disgusting information.
The results of the Ladavas et al. (1993) study suggested that it was the right hemisphere that unconsciously processed both sexual and disgusting information. Furthermore, the findings demonstrate that the brain is unconsciously processing information, causing a physiological reaction, without conscious awareness of the content of the information.
Basic emotions are not only differentiated on the basis of neural pathways, but also on the basis of hormonal activation. This was the conclusion of Henry (1986) on reviewing animal and human research on hormonal responses associated with emotions. Once particular emotional neural circuits are activated, the endocrine system is also activated so that various hormones are released within the body. This results, for example, in changes in blood pressure, pulse, norepinephrine secretion, and testosterone level. Henry (1986) outlined how the overall profile of endocrine activation differs for anger, fear, depression, and elation (see Table 3).
In anger, blood pressure, pulse, and norepinephrine level increases, epinephrine slightly increases, and testosterone increases. In fear, there are moderate increases in blood pressure, pulse, and norepinephrine level, an increase in epinephrine, and a moderate increase in cortisol (an androgen like substance). In depression, there is a slight decrease in pulse, a decrease in testosterone, and an increase in cortisol, ACTH (which is associated with loss of effort, submission, and inhibition of behaviour), and endorphins. In elation, there is an increase in testosterone, and a decrease in cortisol, ACTH, and endorphins. In a situation of helplessness, cortisol levels are high and testosterone levels are low.
Sympathetic and Endocrine Activity for Some Emotions (From Henry, 1986)
Hormones appear to have interesting associations with human behavior. Much of these effects have to do with sexual desire, but other behaviors are affected as well, and male behavior is affected as well as is female behavior. For example, normal maternal behavior is, in part, influenced by oxytocin, vasopressin, and prolactin (Douglas & Ludwig, 2008) and maternal postpartum depression may, in part, be associated with mothers’ estrogen, or prolactin levels (Bloch, Rotenberg, Koren, & Klein, 2005). Similarly, men’s hormone levels have been associated with how they interact with their children. Men with higher levels of prolactin and lower levels of testosterone are more sympathetic to the cries of infants (Fleming, Corter, Stallings, & Steiner, 2002). Prolactin levels are positively correlated (r = .26) to how much time men spend in coordinated exploratory play with their first-born infant (Gordon, Zagoory-Sharon, Leckman, & Feldman, 2010). Father’s oxytosin levels relate (r = .29) to how much time the father and his first-born infant mirror each other in social behavior and emotions during interactions together (Gorden et al, 2010). Finally, paternal postpartum depression exits at rates similar to those of maternal postpartum depression, and may, partially, be associated with the father’s testosterone, estrogen, vasopressin, cortisol, and prolactin levels (Pilyoung & Swain, 2007).
Theorists as disparate as psychoanalysts and evolutionary psychologists agree on one thing: sex is a powerful motive that influences much of our behavior, sometimes in automatic reactions that are often below our conscious awareness. However, sex is not the only biological motive that influences what we do, and in fact it is not even the most powerful motive. Our most powerful biological motive is to survive. Survival trumps sex. Other biological states, such as sleep deprivation, can also overpower our sexual motive\feelings, but nevertheless, our sexual motivation\feeling is a powerful force behind much of what we do. It is quite fitting that one article (i.e., Mass, Holldorfer, Moll, Bauer, & Wolf, 2009) on women’s sex drive was titled “Why we haven’t died out yet ...”
The relationship between lust and other emotions, such as love, is not always simple. While young adolescents may conflate lust with love, adolescents who advocate “friends with benefits” separate sex with friends from feelings of love or commitment. However, college students see lust and love as strongly linked, and perceive relationships that involve a strong mutual sexual desire as happier and more satisfying (Regan, 1998).
Our own emotional expressions affect how sexually attractive others see us. Canadians rate pictures of smiling women as more sexually attractive than pictures of women with either a neutral, shameful, or prideful facial expression (Tracy & Beall, 2011). The size of this effect is significant, a rating of one point higher on a nine point scale. On the other hand, Canadians rate pictures of prideful men as more sexually attractive than they do pictures of smiling men (Tracy & Beall, 2011). This is likely because pride signals higher social status (Tracy & Beall, 2011), and evolution appears to have endowed some women with a tendency to be attracted to men who have the resources to protect a women’s offspring. People’s feelings of lust are not always as simple as we might think.
Sexual relations within a relationship can significantly affect our satisfaction with the relationship, but within heterosexual couples, men and women do not always understand that the strength of their partner’s sexual drive is somewhat different than their own. It is not uncommon for partners to differ in the strength of their sex drives. In fact, although there are individual differences, women generally desire sex less often than do men (Baumeister, 2000; Baumeister, Catanese, & Vohns, 2001). The gender differences in sexual drives exist for biological and\or environmental reasons, and in turn influence several aspects of sexual behavior. In a review of the literature, Petersen and Hyde (2010) found that men reported slightly more sexual experience and more permissive attitudes than did women. Males were moderately more likely to masturbate, view pornography, and engage in casual sex. Men were more likely than women to hold more liberal attitudes toward premarital sex, to endorse the sexual double standard, and to report sexual satisfaction. Women were slightly more likely than men to feel fear or anxiety or guilt about sex, have permissive attitudes toward having sex with emotional commitment, and hold positive attitudes toward gay men. However, while gender differences exist in these areas of sexual behavior and attitudes, most of these differences tend to be of small magnitude (Petersen & Hyde, 2010). No gender difference existed in reported attitudes toward extramarital sex, attitudes toward sex when engaged to be married, attitudes toward masturbation, and attitudes toward lesbians.
The biology behind lust involves brain centers and hormones. Sexual arousal increases activation of the “reward” system in the brain and the deactivation of an inhibitory circuit from the frontal lobe. Other specific brain regions have also been linked to sexual arousal in both men and women. Several fMRI studies have found that viewing sexual pictures results in activation in the visual cortex, the parietal lobe, the orbitofrontal and the anterior cingulate cortex regions, the ventral striatum (part of the limbic system), and the amygdala (Salonia et al., 2010). The hypothalamus becomes activated with sexual signals, and is more easily activated by visual signals in men than in women (Salonia et al., 2010). We all “know” that about men from the everyday world where men seem forever distracted by the mere sight of women around them!
Hormones have been linked to sexual desire and sexual behavior. Testosterone is the hormone that is responsible for men’s sexual drive. For men, high testosterone levels are directly related to a high desire to date others (van Anders & Goldey, 2010). Testosterone increases in sexually experienced men when they simply talk with women, although not during morning conversations (van Anders & Gray, 2007). It also increases with exercise. Women tend to find men with higher testosterone levels more attractive, at least for short-term relationships, but males with higher testosterone levels are more likely to have extramarital affairs, and to divorce (van Anders & Gray, 2007).
The production of testosterone declines slowly with age in men. In middle-aged men, the decrease is about 1% per year, which explains why middle-aged men who are healthy (particularly cardiovascularly healthy) are still interested in sex.
Hormones also have indirect effects on men’s sexual behavior. Testosterone is positively related to dominance, but only if stress levels are low (as reflected by low cortisol) in individuals (Mehta & Josephs, 2010). A man’s social status, including perceived dominance, relates to how attractive many women see that man. High cortisol (a stress hormone) levels are correlated with feeling anxiety and with social avoidance (Mehta & Josephs, 2010). Van der Meij, Buunk, and Salvador (2010) found a moderate (r = .55) correlation between how attractive men found an unfamiliar woman they were with, and the cortisol level in men. It was assumed that the men were nervous when waiting with a woman who they thought of as a potential mate. However, of the 21 men who rated the woman as quite attractive (5 or 6 on a 7-point scale), only 12 actually showed an increase in cortisol. An interesting question is why did cortisol not increase in the other men? The obvious answer is that they were probably not stressed by an attractive woman. Perhaps they were more extroverted or more socially or sexually skilled, and so are not stressed when they meet an attractive woman.
Women’s sexual drive is more complicated, more nuanced, than men’s sexual drive. Incredibly, it has been asserted that 48% of North American women have no sex drive, and that much of this is related to hormone levels (Vanderhaeghe & Pettle, 2007). This assertion should not be lightly dismissed as estimates from surveys suggest that from 7.2 - 54.8% (Emerson, 2010), or from 20 - 30% (Both, Laan, & Schultz, 2010), of women in the United States have low sexual desire. Low sexual desire tends to increase with age, but the percentage of women for whom this causes distress seems not to change with age (Emerson, 2010).
Testosterone plays a key role in women’s sexual drive. As such, the availability of chemicals used by the body to produce testosterone can affect the strength of a woman’s sex drive. L-arginine is an amino acid involved in the production of nitric oxide, which is in turn used in the production of luteinizing hormone, which in turn is used in the production of testosterone. Thus, L-arginine can be seen as responsible for sexual arousal in women (Vanderhaeghe & Pettle, 2007) and, interestingly, is only available through one’s diet (i.e., meat, chicken, turkey, nuts, and milk products).
DHEA, another precursor of testosterone, is produced in the adrenal glans in both men and women (Vanderhaeghe & Pettle, 2007). This hormone is at peak production in women during their twenties, and then declines. This may partly explain the decline with age in the strength of women’s sex drive. As women age, dopamine levels also tend to decrease. As dopamine inhibits prolactin, and prolactin inhibits testosterone, the net result with aging is a decrease in levels of testosterone, and thus a decreased sex drive (Vanderhaeghe & Pettle, 2007). Overall, testosterone levels in women peak at about age 25 and drop to about half of that levels after women have reached menopause (Both et al., 2010).
Hormonal fluctuations make women’s sexual desire more complicated then men’s sexual desire. Sexual desire often varies with the phase of a woman’s menstrual cycle. Wang and Johnston (1993) measured women's responses to pictures (some of them of men) at different times during the women’s menstrual cycle. They found that when progesterone was assumed to be high, eroticism was low. The fertile phase of the menstrual cycle is when sexual desire tends to be at higher levels (Mass et al., 2009). This is when women are most attracted to male faces, masculine bodies, and male social dominance (Gangestad, Thornhill, & Garver-Apgar, 2010). Interestingly, the low progesterone levels during the fertile phase of the menstrual cycle are also associated with increased accuracy of emotional recognition of facial expressions (Derntl, Kryspin-Exner, Fernbach, Moser, & Habel, 2008), which may facilitate successful interactions with potential mates.
Among women who have a hysterectomy, which results in lower testosterone levels, 35-44% report a low sex drive (Graziottin, Koochaki, Rodenberg, & Dennerstein, 2009). This can often lead to conflict with their partner because he will be interested in having sex but she is often just not interested. These women frequently experience a number of negative emotional consequences (Dennerstein, Koochaki, Barton, & Graziottin, 2006). Over 80% of these women feel that they are letting their partner down and\or are unhappy, over 70% feel disappointed and\or frustrated, over 60% feel sad and\or hopeless and\or upset, over 50% feel angry, and over 40% have low self-esteem (Graziottin et al., 2009). In comparison, these emotions are experienced less than 10% of the time in women with normal sexual desire (Graziottin et al., 2009).
For both men and women, the earlier they reached puberty and the earlier their first sexual arousal, then the slightly stronger their adult sex drive (Ostovich & Sabini, 2005). Heterosexual women, and bi-sexual women, with a higher sex drive are more attracted to both men and women than are women with a lower sex drive (Lippa, 2007). However, heterosexual men, and lesbians, with a higher sex drive are simply more strongly attracted to women (Lippa, 2007). Thus, it appears that the sexual response of some women tends to be more flexible that of most men (Salonia et al., 2010).
There is yet another way that women’s lust is more complicated than is men’s lust. Chivers (2010) suggested that women are more likely than men to be physiologically aroused (as measured by blood flow to the genitals) but not subjectively feel sexually aroused. Men are more likely to experience a direct correspondence between their physical and mental arousal. More specifically, for women the correlation between subjective arousal and a physiological measure of arousal is .26, whereas for men the correlation is .66 (Chivers, Seto, LaLumiere, Laan, & Grimbos, 2010).
By no means do hormones play the sole role in lust. Personal, relationship, and cultural factors are all important in determining the strength of one’s sex drive (Emerson, 2010). Upbringing, personal experiences, and socialization affect what we think about sexual relations, and our thoughts have a major influence on our sexual behavior. It has been found that sexual failure/disengagement thoughts are negatively related to desire (r = -.50) while erotic thoughts are positively related to sexual desire (r = −.60) for both women (Nobre, 2009) and men (Carvalho & Nobre, 2011). A More restrictive attitude about sex is also related to lower levels of men’s sex drive (Carvalho & Nobre, 2011). Feelings of anxiety, fear of pain, depressed mood, low self-esteem, low relationship satisfaction, or stress can all lead to a lower sex drive in women (Both et al., 2010).
Women with a high sex drive are much more likely than women with a low sex drive to think about sex, to enjoy fantasizing about sex and get quickly aroused doing so, to believe that they are better than most women at sex, and to really enjoy masturbating to orgasm (Wentland, Herold, Desmarais, & Milhausen, 2009). Feelings of intimacy also positively affect women’s sexual arousal (Both et al, 2010). Women commonly report having sex for reasons of pleasure, love, or commitment (Meston, Hamilton, & Harte, 2009). However, middle-aged women are more likely than younger women to report having engaged in sex a higher proportion of times to reduce stress, to retain their mate, to boost self-esteem, for social status, or ,for a few women, for purposes of revenge (Meston et al., 2009).
Finally, personality may also be related to one’s sex drive. Among women, being highly competitive to get a male sexual partner(s) was associated with lower agreeableness (Buunk & Fisher, 2009). These would be women who might say that other women do not like them. Men who are highly competitive to get a female sexual partner(s) tend to have high levels of both neuroticism and extraversion (Buunk & Fisher, 2009).
Our emotional reactions are partly a result of our particular set of personality traits, and these personality traits are determined by interesting and complex relationships between genetic influences and environmental factors. Infant development illustrates nicely the effects of genes and the environment on personality traits that are tied with emotional reactions. It turns out that infants are born with different temperaments: “Easy,” which involves generally being in a positive mood and open to new experiences; “Difficult,” which involves generally being irritable and reacting negatively to changes in routine; “Slow-to-warm-up,” which involves being somewhat moody and adapting slowly to new experiences; and about 35% of children who do not fit the three identified temperament types. Infant temperament will not only affect the reactions of infants but it can also influence the emotions of the parent. Having an infant with a difficult temperament when one is not expecting it, or when one does not know what to do, can be very stressful for some North American parents. However, although infant temperament appears genetically determined, parenting style can change infant temperament. If an infant is born with a difficult temperament but the parents are calm, restrained, but require their child to follow their rules, then the child’s temperament will likely change (which in Western culture usually means that the parents will get more sleep and be happier!).
Childhood shyness is a personality trait that is closely tied to emotions. Shy children are more anxious than are other children. While there is a genetic predisposition towards shyness, it is only extremely inhibited children (and extremely uninhibited children) who are consistently so doing childhood (Kagan, Resnick, & Snidman, 1988). These consistently shy children have higher heart rates than do their peers and are more likely to experience unusual fears such as of being kidnapped, or of violence on television, or of being alone in their bedroom at night (Kagan et al., 1988). When shy boys become shy adults, they are more likely than their peers to get married later in life, to show lower achievement in their career, and to have marital instability (Caspi, Elder, & Bem, 1988). This suggests that shy males are, perhaps, somewhat more likely than their peer to experience negative emotions in life. It would be interesting to see the extent that relaxation and social skills training might change the pathway in life of shy boys.
Shy girls, on the other hand, tend to take a pathway in life that, arguably, avoids some of the anxiety that comes with uncertainty. When shy girls become shy women they are more likely than their peers to follow the traditional gender stereotype of marrying, having children, and being a stay–at-home mom (Caspi et al., 1988). Shyness (introversion) in adults is moderately associated with anxiety and depression (Kotov, Gamez, Schmidt, & Watson, 2010). So, the personality trait of extreme shyness may influence the individual’s emotional reactions and life course during childhood and adulthood. However, for most children shyness is not a stable trait and so does not predictably affect one’s life course.
Personality tends to become more stable as we get older. We do not know how much of this increased stability is related to: (a) genes more often turning “off” and “on” early in development than in adulthood, or (b) to our experiencing a more stable environment as we get settled as adults, or (c) to something else entirely. Nonetheless, Roberts and DelVecchio (2000) found that that the correlation for personality trait stability (how one ranks compared to others) was .31 in childhood, .54 during college\university, .64 at age 30, and .74 between ages 50-70. Thus, it seems that our personality is pretty stable during adulthood. However, even in late middle-age to early old-age the correlation is not perfect; some people’s personality changes. The personality traits that Roberts and DelVecchio (2000) focused on in adulthood were the “Big Five”: extroversion, neuroticism, agreeableness, conscientiousness, and openness to experience. For adults, the Big Five personality traits correlate with two general measures of emotions: positive emotionality and negative emotionality. The strongest relations are between (a) extraversion and positive emotionality, and (b) neuroticism and negative emotionality.
The personality dimension of extraversion is a reflection of social outgoingness. At one end of the dimension are extraverts who are usually friendly and socially outgoing, while at the other end of the dimension are introverts who are usually shy. Extraverts are more likely to be active, excitement seeking (McCrae et al., 2010), assertive (DeYoung, 2010), ambitious, exhibitionist, and socially dominant (Morrone-Strupinsky & Lane, 2007). The various subtraits that compose extraversion are sometimes conceptualized as belonging to one of two components: (a) emotional warmth in social situations, and (b) arousal to positive stimuli (Morrone-Strupinsky & Lane, 2007).
Extraverts are more likely than others to be happy. Extraversion accounts for between 2-16% of happiness (Nettle, 2009). One of the things that extraverts do to help them feel happy is to re-evaluate negative events in a more positive way (Wang, Shi, & Li, 2009). They tend to see the glass as half full and they appear to be more attuned to the pleasant things in life.
Extraversion is positively associated with self-ratings of feeling joy (r = .66), love (r = .59), pride (r = .58), contentment (r = .48), compassion (r = .33), awe (r = .34), and amusement (r = .26) (Shiota, Keltner, & Oliver, 2006). Extraversion is positively related to the frequency, strength and duration of the experience of these various positive emotions (Verduyn & Brans, 2012). Extraverts are also seen by their peers as experiencing pride (r = .34) and contentment (r = .26) (Shiota et al., 2006).
Regarding the direction of causal relations, extraversion, at least partially, causes positive emotions. One study (McNiel & Fleeon, 2006) experimentally manipulated extraversion by having participants act in either an extraverted or introverted manner in two sessions when talking with others. Those who acted in an extraverted manner reported feeling more positive emotions and were rated by observers as showing more positive emotions. Keep in mind that social skills training can increase extraversion (Nelis et al., 2011).
Most of us probably intuitively know that being able to be outgoing and to easily make friends feels good. Probably because they have good social skills and a positive attitude, extraverts have more romantic relationships than do others (Nettle, 2009).
At the same time, extraverts experience just as many negative emotions as do other people (Nettle, 2009). So, extraverts experience more happiness but just as much pain and sorrow as others. In fact, their family life may actually be less stable because of their tendency to be restless (Nettle, 2009). When that happens, extraverts tend to cope with marital stress through compromise and self-blame, as well as through confrontation and withdrawal (Lee-Baggley, Preece, & DeLongis, 2005).
The personality dimension of neuroticism is a reflection of some people’s tendency towards anxiety and emotional instability. People high in neuroticism are more anxious, tense, touchy, irritable, impulsive and emotionally unstable. Fear, sadness, guilt, and hostility are all strongly related to neuroticism. People high in neuroticism are more likely to express themselves through emotional venting (Boyes & French, 2011) or affective aggression (Egan & Lewis, 2011). They are also more likely to later apologize (Howell, Dopko, Turowski, & Buro, 2011).
People high in neuroticism are more vulnerable (McCrae et al, 2010) and more likely to experience fatigue (Grühn, Kotter-Grühn, & Röcke, 2010). When they are feeling sad then they are more likely than others to experience nostalgia (i.e., sad and yet wistful joyous memories and feelings) when listening to music (Barrett et al., 2010). They are also more likely to worry, be self-conscious, and to be self-critical. They have a tendency to feel sorry about themselves.
Neurotic people are less likely than others to be happy. Neuroticism accounts for between 6-28% of happiness (Nettle, 2009), a fairly significant amount. However, individual differences in neuroticism are [only] moderately related to genetic differences (Sprangers et al., 2010), which means that environmental factors have a moderate effect on differences on neuroticism within the population. The silver lining in all this is the possibility that environmental factors may cause people high in neuroticism to change their thinking, leading them to become less neurotic and happier with life.
The thinking of people who are high in neuroticism is different than those who are low in neuroticism. People high on neuroticism see, and think of, the glass as half empty. They fail to perceive a negative situation in a more positive way (Wang et al., 2009). They are more likely to see threats when others do not (Hervas & Vazquez, 2011). They are more likely to ruminate about a situation (Hervas & Vazquez, 2011). That is, they are more likely to think about the situation over and over and over again, perhaps trying to understand why others did what they did or how they themselves might have acted differently. Those high on neuroticism are less likely to regulate their negative emotions than are other people (Ng & Diener, 2009). Wang et al. (2009) found that those Mainland Chinese students who are high in neuroticism are less likely than their peers to reevaluate a situation in a more positive light. People high in neuroticism also engage in more wishful thinking and more withdrawal from situations (Connor-Smith & Flachsbart, 2007). These various problematic thought processes contribute to their experiencing more negative feelings (Wang et al., 2009). For some people this can also lead to relationship problems or other serious problems.
An example of how neuroticism affects family life is the finding that men who are both high in neuroticism and stressed at work, upon returning home after work, tend to have negative interactions with both their spouse and children (Wang, Repetti, & Campos, 2011). Neuroticism before marriage predicts later separation and divorce (Lahey, 2009).
As for even more serious consequences, neuroticism is strongly associated with anxiety disorders and is moderately associated with depression (Kotov et al., 2010). People high in neuroticism are more likely to engage in risky behaviors and are more likely to be dependent on alcohol or drugs. Neuroticism is related to not only the quality but also the longevity of an individual’s life (Lahey, 2009).
Agreeableness reflects a tendency to actively try to get along with, and help, other people. Highly agreeable people are considerate of the feelings and desires of others (DeYoung, 2010). Those high in agreeableness are more understanding of the thoughts and intentions of others, and have more empathy towards others (DeYoung, 2010). This would explain why there is a weak positive relationship between agreeableness and both the frequency and intensity of feeling sad (Pearman, Andreoletti, & Isaacowitz, 2010). Their higher empathy means that people high in agreeableness reactive slightly more than others, in sad situations. People who are high in agreeableness are good at controlling their own emotions (Pearman et al., 2010) and at suppressing socially disruptive emotions (DeYoung, 2010).
Conscientiousness and perfectionism
Conscientiousness reflects one’s tendency towards self-discipline and organization (DeYoung, 2010). High conscientiousness has been associated with academic and occupational success, and with behaviors that enhance health and longevity (DeYoung, 2010). Not surprisingly, in a large sample of German adults, consciousness (and openness to experience) was positively correlated with positive emotions (Grühn et al., 2010). However, like most things, too much conscientiousness is not always a good thing.
Traits that are subcomponents of the Big Five, or that are extreme of one of the Big Five personality dimensions, have also been linked to emotions. An example is perfectionism, which can be considered as the high end of conscientiousness (Costa & McCrae, 2010). A perfectionist is an individual who frequently strives to be perfect (e.g., in university courses, in work, etc) and who often feels very negatively (anxious or depressed) when he or she does not perform absolutely perfectly (e.g., “only” getting 93 on a university exam). Associated with perfectionism are a number of thought processes that lead to negative emotions: (a) catastrophizing (i.e., thinking that the worst consequences will happen) (b) rumination (i.e., continually thinking about the “failure”), and (c) self-blame (Rudolph, Flett, & Hewitt, 2007). If one member of a romantic couple is a perfectionist then the couple is more likely to experience conflict, and the perfectionist is more likely to later experience symptoms of depression (Mackinnon et al., 2012). If perfectionists do not live up to their own expectations in a given sport, they often experience shame and guilt. However, it has been suggested that the process of striving to improve is healthy; what can be maladaptive is the unrealistic concern that one is not being perfect (Stoeber, 2011).
A general point that I wish to stress about personality traits is that although personality traits have a genetic component and are largely stable in adulthood (Terracciano, McCrae, & Costa, 2010), they can change for some if the environment or the individual’s thinking processes change. Changes in the environment can sometimes cause genes to turn on or off.
Nelis et al. (2011) demonstrated that 18 hours of emotional competency training lead to an increase in extraversion and agreeableness, and a decrease in neuroticism that lasted to the final assessment (6 months after training). This type of training can lead to an improved quality of life. So, although it may not be easy, someone who is high on neuroticism and\or perfectionism can be taught to change their thinking, or might experience an epiphany because of some significant life changing experience, with the result being that life becomes more enjoyable for both them and the others around them.
Alexithymia is a clinical construct involving poor emotional self-awareness on the part of an individual. They have problems in being aware of, describing, and understanding their own emotions. For example, stressful situations do elicit sympathetic nervous system arousal in people high in alexithymia, but these individuals do not perceive themselves as anxious (Pollatos et al., 2011). Also, males (but not females) with high levels of alexithymia may misinterpret the increased heart rate associated with an emotion as chest pain that requires medical attention (White, McDonnell, & Gervino, 2011). People with high levels of alexithymia also tend to have a lack of imagination (i.e., a lack of fantasies) and show a tendency towards concrete externally-oriented thinking, as opposed to emotionally driven thinking. It is estimated that alexithymia occurs in about 10% of the general population.
For some, alexithymia appears to be a stable personality trait. Approximately 30-33% of difference on the (normally distributed) dimension of alexithymia has been related to genetic factors (Walter, Montag, Markett, & Reuter, 2011). There appears to be processing anomalies in several brain regions: the insula, cingulate cortex, and corpus callosum (Wingbermühle, Theunissen, Verhoeven, Kessels, & Egger, 2012). From a biological perspective there may actually be two subtypes of alexithymia. Type 1 involves the lack of transfer of information (via the corpus collosum) from the right to left hemisphere, resulting in problems in both descriptions of emotions and in emotional coping skills (Wingbermühle et al., 2012). Type 2 only involves problems in emotional coping skills (Wingbermühle et al., 2012).
For other people, alexithymia may be a temporary state brought about because of brain injury or post-traumatic stress disorder (Wingbermühle et al., 2012). Self-reports of childhood abuse and neglect are moderately correlated with alexithymia in adulthood. One study (Thorberg et al., 2011) found that quality of adult attachment accounted for 25% of the variance in alexithymia.
Social skills can be a problem for those with alexithymia. People with alexithymia can have difficulty in recognizing emotions in others. They are less likely to be sociable and are more likely to have social problems (Nicolò et al., 2011). They tend to be cold: lacking social intimacy and lacking empathy. They tend to be insensitive to their sexual partners and because of this often have multiple sexual partners.
Individuals with high levels of alexithymia are much more likely than others to develop anxiety disorders and depression (Wingbermühle et al., 2012). Perhaps because their emotional responses are less likely to be modified by thought processes, alexithymia is also correlated with eating disorders, drug and alcohol abuse.
Alexithymia has been linked to narcissism and to psychopathy. However, according to Louth, Hare, and Linden (1998) alexithymia is not the same thing as psychopathy. They suggest that while psychopaths may charm others, individuals high in alexithymia tend to bore others. Psychopaths may fake emotions they do not experience, whereas people high on alexithymia cannot fake their emotional responses because they do not understand their emotions well enough to do so. Incarcerated female prisoners who are high in alexithymia are more likely to engage in violent crimes, perhaps because they cannot imagine or sense the feelings of victims (Louth et al., 1998).
Summary of the Biological Foundations of Emotions
So, this section on the biological foundations of emotions, hopefully, demonstrated that emotions evolved because of our evolutionary history. As a result, humans share a small number of basic emotions. These basic emotions are associated with distinct brain processes and hormonal reactions. Some of this physiological processing of emotions occurs at an automatic (unconscious) level. Genetic differences also give rise to personality differences, which have a significant impact on emotional experience. However, these personality differences and their associated styles of emotional responding are not necessarily fixed, but may sometimes be altered by environmental events and by changes in an individual’s thought processes.