Even though you've probably experienced a wide range of emotions for as long as you can remember, it still may be tough to say what an emotionemotionA multi-component response involving physiological arousal, cognitive appraisalcognitive appraisalThe interpretation of a stimulus that determines which emotion is felt — emphasized by Lazarus., and behavioral expression. is. So while you probably know that an emotion is a feeling, if you're having a hard time defining it, that's ok, you're not alone. It turns out that psychologists also struggle with defining specific emotions. Instead of attempting to carefully define each emotion, psychologists find it easier to talk about emotions by making comparisons. We may struggle to say exactly what happiness is, but we can generally agree that it's better than sadness.

Using a technique called multidimensional scaling, we can compare emotions to one another and then map them out on two main dimensions. The first dimension is how strongly an emotion can be considered a positive or negative experience, referred to as valence. The second dimension is to consider how an emotion relates to our physiological arousal; some emotions like fear, excitement, or surprise have our hearts racing, while others, like boredom, calmness, or depression are characterized by low levels of arousal. While these aren't the only two dimensions we could use to think about emotions and we may not always agree on exactly where emotions fall on these dimensions, this approach gives us a way of organizing and comparing emotional experiences.

When we consider how emotions differ in terms of physiological arousal, we may begin to wonder how this process gets started. There are several approaches to thinking about the relationship between arousal and emotional experience. The first of these, suggested independently by William James in the United States and Carl Lange (pronounced lawn-guh) in Denmark, is referred to as the James-Lange TheoryJames-Lange TheoryThe theory that emotions follow from awareness of physiological arousal — we feel afraid because we tremble. of Emotion. This theory suggests that an emotional experience is the result of physiological arousal. In other words, we see a stimulus, this stimulus influences our level of arousal, and this physiological activity causes us to experience a particular emotion. A classic example is walking in the woods and suddenly seeing a large bear. This stimulus causes your heart to race, and your racing heart tells you that you are afraid.

This may seem fairly logical, but the problem we have is that this theory doesn't address how different emotions might arise from similar physiological states. Your heart may also race while you are exercising, but this doesn't cause you to experience fear.

Later theorists Walter Cannon and his student Philip Bard suggested that instead of a chain-reaction, a stimulus causes both the nervous system activation and the emotional experience at the same time, known as the Cannon-Bard TheoryCannon-Bard TheoryThe theory that the thalamus simultaneously sends signals to the cortex (emotion) and body (arousal) — they occur together. of Emotion. This would mean that the bear causes your heart to race and it causes you to feel afraid at the same time. This theory helps explain some scenarios that don't fit the James-Lange Theory, such as blushing. In the case of embarrassment, people often experience the emotion immediately though the tell-tale physiological sign of a flushed face is slightly delayed (taking 15-30 seconds to occur). So if you were to accidentally fart in class you probably wouldn't need to wait until your face was red to feel embarrassed.

Stanley Schachter and Jerome Singer proposed that the stimulus and our general level of physiological activity are combined and interpreted to give us our emotional experience, and this is known as the Two-Factor Theory of Emotion. In an experiment to demonstrate this, participants were given an injection of epinephrine, which increased their physiological arousal. Some of the participants were told the truth about what the drug would do (increase heart-rate, breathing, etc.) while others were misled (told it would cause numb hands, itchiness, and a headache). The participants then interacted with a confederate in a waiting room who acted either goofy (making paper airplanes, tossing balls of paper, and twirling hula hoops) or enraged (tearing up a survey form and storming out because of questions such as: With how many men (other than your father) has your mother had extramarital relationships?).

During and after this interaction, participant behaviors were observed and they completed a self-report of their emotional state. The ones who had been told the true effects of the drug reported feeling relatively normal but the participants who had been misled were more likely to report feeling giddy or angry depending on which confederate they had interacted with. It seems these participants were experiencing strong physiological arousal but since they didn't know where this arousal was coming from (the epinephrine), they incorrectly assumed it was part of their emotional state. By manipulating cognition, Schachter and Singer were able to influence emotional state.

This provides evidence that an emotional experience is not just a physiological response to a stimulus but an active cognitive appraisal, in which we assess and ascribe meaning to how our body is feeling. This interpretation isn't always correct and we can be fooled by our physiological arousal and misinterpret our emotional experiences, known as misattribution of arousal.

Our physiological reactions influence our emotional state when we believe they're relevant. Stuart Valins found that men's sense of attraction to women's images could be influenced by hearing a false-heart beat (which they believed was their own) that sped up when viewing the pictures. The effect of hearing heartbeats was also demonstrated at a live podcast recording by WNYC's Radiolab in 2015 when a loud heartbeat sound used in the show caused many listeners to feel dizzy, and even caused some listeners to faint.

Misattribution of arousal was perhaps most famously demonstrated by Donald Dutton and Arthur Aron in 1974 when they found that men were more likely to call the phone number left by a female interviewer if they met her while crossing the shaky Capilano suspension bridge in Vancouver than if they met her on solid ground elsewhere in Capilano park. Dutton and Aron suggested the bridge caused the pounding heart and sweaty palms men experienced but that these signals were misattributed as signs of attraction to the woman.

In 1936, Heinrich Klüver and Paul Bucy removed the temporal lobes of rhesus monkeys and discovered that the monkeys then tried to eat all sorts of inedible items and also became hypersexual, attempting to mate with just about anything. Another result of the surgery was that the monkeys remained incredibly calm when handled and no longer showed signs of fear, even when faced with snakes. These traits became known as Klüver-Bucy syndrome, or temporal lobe syndrome.

Despite this name, it turns out that it wasn't removal of the temporal lobe that was responsible for these changes but damage to subcortical structures in the limbic system. A few decades later, research by James Olds and Peter Milner revealed that an area of the hypothalamus known as the nucleus accumbens plays a key role in motivations for hunger and sex. Rats who could self-administer electrical stimulation to this area by pressing a lever would ignore food, sleep, and potential mates, pressing the lever continuously until they collapsed from exhaustion. At the time, Olds and Milner thought they had found the “pleasure area” of the brain, but later research revealed a more appropriate name would be the “reward area”. It wasn't just that the stimulation was pleasing the rats; it was motivating them to keep pressing the lever.

As for the lack of fear in Klüver and Bucy's monkeys, this was probably the result of damage to another structure of the limbic system: the amygdalaamygdalaA limbic system structure critical for processing fear, emotional memories, and threat detection.. The amygdala seems to be a key area for appraising a stimulus and determining an emotional response. Without properly functioning amygdalae, it seems that these monkeys could not correctly identify the threat posed by a snake, and therefore did not show fear. Their emotional appraisal was impaired, meaning that they weren't able to assess what was happening or why it mattered.

Joseph LeDoux has proposed that our emotional response to a stimulus occurs via two different pathways: a fast pathway which quickly jumps to the amygdalae, and a slow pathway involving the cortex. The fast pathway or “low road” quickly determines if something is good or bad and prepares us for immediate action. The slower pathway, or “high road”, involves the cortex of the frontal lobes and takes time to identify the stimulus and consider its importance, at which point we can modify our course of action. You've experienced the time delay between these two pathways if you've ever been startled by something unexpected (fast pathway) and a moment later identified it as harmless (slow pathway). Richard Lazarus has suggested that some of the process of appraisal is occurring unconsciously and Robert Zajonc has suggested that we have no conscious awareness of some of our emotional reactions. This can be seen in studies in which people have shown fear reactions to stimuli even when the stimuli were presented too quickly for conscious awareness (see Whalen et al, 1998).

Unfortunately, improved understanding of emotion in the brain also has a dark history. The prospect of blunting emotions led to attempts to sever connections in the brains of human patients who were prone to emotional outbursts. Egas Moniz, a Portuguese neurologist, developed the leucotomy in 1936, a procedure which involved drilling a hole in the skull and inserting an instrument to cut fibers between the frontal lobes and the thalamus. Moniz was later awarded the Nobel Prize in 1949 (though in recent years some have called, unsuccessfully, for the Nobel Committee to rescind this award). This procedure was renamed the lobotomy and popularized in the United States by neurologist Walter Freeman and neurosurgeon James Watts. In 1937, Freeman and Watts began performing the procedure and quickly found thousands of patients, the most famous of which was 23-year old Rosemary Kennedy (sister of John F. Kennedy), who spent the rest of her life institutionalized and incapable of speaking after an unsuccessful lobotomy.

Freeman later simplified Moniz's procedure to the transorbital lobotomy; chiseling an icepick-like-instrument through the eyesocket rather than drilling a hole in the skull. Watts took issue with Freeman's new procedure and severed ties, though this new technique meant that a surgeon was no longer necessary and Freeman began performing the procedure himself (rendering unconsciousness using electric shocks and shocking physicians by not wearing gloves or a mask while “operating”). Freeman traveled throughout the US, visiting psychiatric institutions and Veteran's Affairs centers in a camper he called the “lobotomobile”, promoting use of the procedure by psychiatrists. An estimated 40,000 lobotomies were performed in the United States (Freeman claiming at least 3,500 himself), most during the 1940s and 50s, though the practice continued into the 1970s in some states. As with forced sterilizations, this procedure has been alleged to have been used to silence some members of society, including prisoners and political dissidents.

Lobotomies fell out of favor or were banned in many places, partially due to the advent of new medications, but this wasn't the end of psychosurgery. Decades later some still advocated for procedures involving destruction or removal of parts of the limbic system in attempts to reduce violent behavior and aggression. Other psychosurgeries such as cingulotomies have been used in the treatment of Obsessive-Compulsive-Disorder (with mixed results) and similarly controversial procedures are still being carried out for drug addiction and mental illness in China, where a heated needle is sometimes used to destroy brain tissue in the nucleus accumbens.

The involvement of the frontal lobes in the slow pathway suggests their role in cognitive and behavioral strategies to control and regulate our emotional experiences. Understanding emotional regulationemotional regulationThe process of monitoring, evaluating, and modifying emotional reactions. can also help us to deal with negative emotions. Research by Richard Lazarus and Elizabeth Alfert found that emotional reactions to watching a video of a circumcision were reduced and rated less distressful when the event was described as a joyous religious ritual. In the chapter on Stress and Health, we'll also look at how we can change our emotional reactions to stressful stimuli by engaging in this type of reappraisal, in which we reconsider possible meanings for stimuli.

We know that regulating emotions is predominantly a job for the frontal lobes. We all adopt cognitive or behavioral strategies to try to influence our emotions, whether to help us feel better or prevent us from feeling worse. Based on our previous chapter, you may now be starting to see some connections between our ability to control and regulate our emotions and what might constitute part of our individual personality (particularly when it comes to traits like conscientiousness or neuroticism). When we start thinking about the ability to regulate emotions and control behavior as a function of particular brain regions, this can also raise some unsettling moral questions. What happens when cortical damage influences a person's ability to regulate and control their emotions?

Questions of accountability and culpability aren't just thought-experiments and represent real problems that the future of psychology may be forced to answer. This may make us wonder just how we assign blame; do we blame the person or blame a faulty brain? Given the accidental nature of his injuries, we might hesitate to place blame on Phineas Gage for any moments of rage. After all, what can we expect from a man missing a chunk of his brain? But what if Gage were to commit a crime? Or what if his accident wasn't quite so severe? What if it were only a concussion, but one which caused damage to the same brain regions? Or what if instead of injury, a genetic defect was impairing prefrontal cortex function? This is where things get murky.

We might consider the case of Charles Whitman, who perched himself in a clocktower and shot dozens of people in Austin, Texas in 1966. How much do we blame the man, and how much do we blame the pecan-sized brain tumor discovered in autopsy? Where do we draw the line when we discover that the prison population has about 7 times the average incidence of traumatic brain injury in the United States? How should we think about punishment for these “bad brains”?

Our emotions are more than just internal feelings and they have several ways of making themselves known to others. Our emotions find their way out through speech, tone of voice, eye gaze, posture, and perhaps most importantly, through facial expressions. More than forty different muscles in the face work together to reliably produce actions which are tied to particular emotional states. But how do we learn these movements and how do we know what they mean?

In line with his ideas on natural selection, Charles Darwin proposed that the expression and recognition of emotions had evolutionary significance. Immediate knowledge of someone's anger or fear could aid your survival, so it would follow that this ability might be inherited. Darwin's universality hypothesis suggested that humans around the globe expressed certain emotions in the same way, regardless of their culture or upbringing. After weathering the storms of strict behaviorism and cultural relativism in the early-to-mid twentieth century, it appears Darwin's theory was right. The evidence supporting universality comes from a number of sources, from infants who smile just days after birth, to members of isolated tribes and congenitally-blind individuals whose facial expressions all match the emotions we would expect.

Paul Ekman, who conducted early research examining the facial expressions of the Fore tribe in Papua New Guinea, proposed that there are 6 emotions with universally recognized expression: joy, sadness, anger, fear, surprise, and disgust. Chances are that you could easily recognize these expressions on someone's face, regardless of the person's language, culture, or region.

Another point of support for universality is the widespread adoption of emoticons in communication around the world, suggesting that people easily understand the emotions behind these simple images of faces. Emojis (from the Japanese 絵文字 “picture character”) on the other hand, can be confusing because they may include culturally-specific references which are not universal (such as hand gestures, foods, sports, or celebrations).

Our facial expressions aren't just the consequence of emotions, they are also part of the cause. This idea that how we move our face tells us how we are feeling and influences our mood is known as the facial-feedback hypothesis. This hypothesis suggests that emotions are self-reinforcing, meaning that expressing emotions increases their strength. In one study students who held pencils in their teeth (to simulate smiling without asking them to smile) reported higher moods than those in the control group. It seems that smiling doesn't just show that you're happy, it can make you feel happier too.

Of course, you can't walk around grinning like an idiot all the time, even if it does make you feel good. Expressing and recognizing emotions is fundamental for smooth social interaction, but there are times when we don't want our face giving away our mood. This isn't just for the poker table, but for a wide variety of social interactions, and different cultures have different display rulesdisplay rulesCulturally specific norms governing how and when emotions should be expressed. for when certain expressions are acceptable. No matter what's going on in your mind, you probably don't want to be beaming at a funeral or grimacing at a party. At times we may want to intensify (smile big as if that gift is really great), de-intensify (don't look quite so happy to see your friend's girlfriend), mask (force a smile to hide your contempt), or neutralize emotional expressions (stay stone-faced despite those pocket aces). But despite our best efforts, our bodies and faces often betray us, sending out signals of how we truly feel which trained observers can learn to detect.

Here's a few tips for spotting whether an emotional expression is likely to be genuine, though remember that these are guidelines, not hard-and-fast rules. Sometimes the form or morphology of an expression can reveal the truth, such as a genuine smile, which involves crinkling around the eyes that is tough to fake. Other clues include symmetry (genuine expressions tend to be somewhat asymmetrical), duration (genuine expressions usually last about 0.5 to 5 seconds, but of course, you already knew that never-ending beauty pageant smile didn't seem right) and temporal patterning, which refers to how smoothly an expression appears and fades on someone's face; not surprising if you consider the all-too-sudden and not-too-sincere smile that jerks itself on to some jerk's face.

Deception isn't just in our faces, and other clues can be used to help identify when someone is lying. Despite generally high levels of confidence, it turns out that most people aren't particularly good at detecting liars and don't do much better than chance when put to the test. There are things to look for, however, and trained observers are able to detect liars with about 80% accuracy. What are they noticing? It might not be the things you think.

Many people incorrectly assume that liars can be spotted because they talk too quickly and avert their gaze, but neither of these is strongly associated with lying. In fact, liars tend to talk more slowly, take longer to answer, and include less detail in their responses. Truth-tellers tend to be more engaging, more fluent, and they tend to include imperfections, superfluous details, expressions of self-doubt (I think he was wearing a blue shirt but I'm not really sure) and spontaneous corrections (it was about 5pm, no, 4pm). It's a bit ironic that these types of “errors” are avoided by liars, who seem to think that self-correction or doubt will give them away, when in fact it's a lack of correction and doubt that can indicate lying.

Now you may be wondering about the accuracy of lie-detectors. A polygraphpolygraphA 'lie detector' machine measuring physiological arousal (heart rate, breathing, skin conductance) — not a reliable indicator of deception. (Greek for “many writings”) tracks a number of physiological changes in the body, including heart-rate, blood pressure, and galvanic skin-response, which indicates sweating. We should remember that despite their popular name, these machines aren't actually detecting lies but simply measuring physiological changes in the body during questioning. While the assumption is that lying will be revealed through patterns of physiological activity, this will not always be the case. People can be trained to fool a polygraph, and people who aren't lying can give false positives. While polygraphs are a bit better than chance, they aren't good enough to establish certainty as to whether or not someone is lying.

While you probably aren't running from bears on a daily basis, emotions play a major role in everyday life. When we think about anything that feels good or bad, we're relying on an emotional assessment. The hedonic principle is the idea that we want to experience pleasure and avoid pain. From this view, we can see how emotional experiences help us to know what is good (it's good because it feels good).

Antonio Damasio studied a patient named Elliot, whose brain damage from an accident reduced his emotional responses. With reduced emotions, we might expect a person like Elliot would be completely rational in his decision-making. Instead, patients like Elliot struggle to make even the most mundane of daily decisions. Choosing an appointment time became an endless consideration of pros and cons because Elliot never found a time that felt right. Without any emotional cues for what was good, he could flounder endlessly between equally dull options. He didn't vacillate because he cared about the outcome, his indecision was the result of what we might consider severe apathy. Decision-making relies on emotional responses to help guide behavior.

Other patients with brain damage to their limbic system have suffered from a bizarre condition known as Capgras Syndrome in which they believe that a loved one has been replaced by an imposter. William Hirstein and Vilayanur Ramachandran have proposed that this preposterous belief in imposters results from a lack of emotional response when the patient sees the person. Without the emotional response that used to accompany the sight of Mom, the patient infers that this must not be Mom. Once again we see just how much it matters that things feel right.

When we ask why we have emotions, our main answer is likely to be that emotions motivate us. Positive emotions motivate us to seek out pleasurable experiences, while negative emotions signal which situations we should avoid.

One early way of thinking about motivationmotivationA need or desire that energizes and directs behavior toward a goal. was based on instincts, which didn't require any previous experience in order to motivate behavior. Instincts were considered to be inherited tendencies activated by features of the environment which made us seek out certain goals. For example, we would have an inherited tendency to seek out food, not because of anything we learned, but simply because this instinct would help us to survive.

The concept of instincts seemed to be a good way of thinking about motivation, but the problem was that it was hard to tell which behaviors were the result of inherited instincts and which were learned. Early psychologists, including William James, quickly piled up a list of thousands of instincts, which meant that many of these supposed instincts were merely new names for behaviors rather than explanations of behaviors. This unwieldy number of instincts, combined with the rise of behaviorism and its emphasis on learning meant that the study of instincts was soon on the decline.

But despite a heavy emphasis on environment, even behaviorists had to admit that other factors influenced behavior. After all, a well-fed rat in a cage with food may just sit there but wait a few hours and without any change in the environment eventually you'll see a change in behavior and the rat will begin eating. How could this fit into the stimulus-response explanation for behavior if there doesn't appear to be any new stimulus? Rather than falling back to the idea of instincts, behaviorists used a new term which referred to much the same thing: a drive. A drive was considered to be a change from an optimal physiological state which motivated certain behavior in order to return the organism to that optimal state. In the example above, the hunger drive was what was now compelling the rat to eat.

This idea of drives is closely linked to the concept of homeostasishomeostasisThe body's tendency to maintain a stable internal environment — regulating temperature, blood sugar, etc., which is that the body wants to maintain a particular state and any departures from that state create drives to modify behavior. Drive reduction theoryDrive reduction theoryThe theory that biological needs create unpleasant states (drives) that motivate behavior to restore homeostasis., developed by Clark Hull, stated that a behavior was rewarding because it reduced a drive, so in our previous example, the reward would not be the food itself, but the reduction of the hunger drive.

Drive theory also distinguishes between primary and secondary drives. A primary drive would be for something that aids our survival, like food, water, or warmth, while a secondary drive doesn't aid survival directly but is associated with a primary drive. The drive to earn money, which can then be used to buy food, would be a secondary drive, though the theory doesn't adequately explain how a money-earning behavior would actually reduce a drive and thus be rewarding.

The opponent process theory of motivation, described by Richard Solomon, suggests that emotions are paired, with each emotional experience having a primary process and an opponent process. With each successive exposure, the strength of the primary process is reduced, while the opponent process is strengthened. Solomon and J.D. Corbit considered emotional responses in skydivers, finding that first-timers mostly experienced fear, while experienced skydivers showed little fear and higher joy. Similarly, dogs which were given electric shocks initially showed anxiety after the shocks, but with repeated exposure, the end of a shock period seemed to bring relief and contentment.

Another way of thinking about what motivates our behavior is Arousal Theory. This is similar to some of the ideas of stimulation we discussed in the previous chapter on personality. In the context of introverts and extraverts, we considered how differing levels of cortical arousal may influence their preferences. Arousal theory considers this as a more general explanation of behavior and proposes that we each have an optimal level of arousal that we want to reach, and so we are motivated to seek out behaviors which will increase or decrease our level of arousal. When arousal is below the optimal level we are motivated to do things to increase it and when arousal is above the optimal level we are motivated to decrease it.

The Yerkes-Dodson law, proposed by Robert Yerkes (yes, the same Yerkes from the intelligence chapter, pronounced yer-keys) and John Dodson, suggests that peak performance on a task is associated with a particular level of arousal and departures in either direction (arousal too low or too high) will decrease performance, creating a curve similar to an inverted U. Yerkes and Dodson formulated this theory by observing how quickly mice learned a task in the presence of weak, moderate, or strong electric shocks, finding that both low and high shocks reduced performance compared to moderate shocks. You might imagine yourself taking an exam; if you don't care at all about the results you might not do well (not bothering to check answers, etc.) or if you're extremely anxious your performance would also suffer (unable to focus, second-guessing every answer, etc.) while some middle level of arousal would allow you to do your best. A mnemonic you might use is thinking “Your key (Yerkes) is to find the optimal level of arousal.”

A related notion is the concept of flow, proposed by Hungarian psychologist Mihaly Csikszentmihalyi (pronounced me-high cheek-sent-me-high). When an activity doesn't challenge us we become bored, and when a task is too demanding for our skills we experience anxiety but when we find an ideal balance of challenge and skill, we experience flow and become deeply absorbed in the task.

We all eat, and we've all probably experienced hunger, though hopefully not in the extreme. We've already considered hunger as an example of drive theory, but how exactly does this hunger signal work?

There are two parts to the hunger signal: the orexigenic signal is the “on” signal that motivates us to eat (you can remember Orexigenic and On), while the anorexigenic signal is the “off” signal when we feel full and stop eating. Both of these signals rely on biological cues controlled by hormones, as well as psychological cues like our memory of when we last ate, visual stimuli like an appetizing dessert tray, and cultural preferences for particular tastes.

Hormones involved in the orexigenic signal include orexin, which is released by the lateral hypothalamus in the brain, and ghrelin, which is released by the stomach when it is empty (you can think of your stomach growling to remember ghrelin). Rats with damage to the lateral hypothalamus never seem to get hungry and will starve to death if they aren't force-fed. Several other hormones are also involved in hunger, including insulin, which is released by the pancreas and helps to regulate blood glucose levels.

The satiety signal indicating that we are full involves another area of the hypothalamus called the ventromedial hypothalamus, in addition to involving the hormone leptin, which is released by fat cells. Destruction of the ventromedial hypothalamus in rats seems to disrupt their satiety signaling, and they eat significantly larger amounts of food, eventually tipping scales at 2 to 3 times their normal weight. This weight gain may also be related to a faster gastric emptying rate, with food moving out of the stomach so quickly that the “full” signal is impaired.

Bulimia NervosaBulimia NervosaAn eating disorder characterized by cycles of binge eating followed by compensatory purging. is an eating disorder in which patients binge eat large quantities of food, then purge by vomiting, using laxatives, or exercising excessively. Bulimia nervosa is associated with negative emotions like sadness, anxiety, and shame, and sufferers can feel trapped in a destructive cycle: bingeing to cope with negative emotions, purging to reduce regret, then experiencing guilt and shame from purging. Binge-Eating DisorderBinge-Eating DisorderAn eating disorder characterized by recurrent binge eating without compensatory purging. was recently added to the official diagnostic list of disorders (the Diagnostic & Statistical Manual of Mental Disorders - Fifth Edition, or DSM-5) and refers to episodes of binge-eating and feelings of guilt and shame, without any compensatory purging behaviors.

Anorexia NervosaAnorexia NervosaAn eating disorder characterized by severe food restriction, intense fear of weight gain, and distorted body image. is an eating disorder characterized by severe food restriction and fear of weight gain, usually accompanied by a distorted sense of one's own body shape and size. Unfortunately it's not the case that patients just need to eat something to solve their problems and popular misconceptions of the disorder can increase the stress that sufferers face.

Eating disorders have high rates of mortality, but they can be successfully overcome with treatment and therapy. There's still a strong social stigma attached to eating disorders and resulting shame or embarrassment can prevent sufferers from seeking the help they need before it is too late. Like most disorders, eating disorders seem to involve complex interactions of genes, family environment, stress, hormones, and cultural pressures.

The widespread struggle with obesity demonstrates the evolutionary origins of hunger signaling. The genes our ancestors passed along have given us a preference for calorie-dense foods as uncertain food supplies and lengthy famines were common in our evolutionary past. As a result, our genes have predisposed us to crave calorie-rich foods that would better prepare us to survive lean times. For most people today, however, lean times are few and far between and our evolutionary habit to gorge ourselves in times of plenty means that we are gorging ourselves all the time. We also have a predisposition to gain weight because it is easier for our bodies to store calories than burn them. As we all know, it's easier to finish off those fries in just minutes, while burning those calories off at the gym takes significantly longer.

Obesity is often defined in adults based on their Body Mass Index (BMI). BMI is calculated by dividing one's weight in kilograms by one's squared height in meters. BMI scores from 18.5 to 24.9 are considered normal, while those below 18.5 are considered underweight, 25-29.9 overweight, over 30 obese and over 40 morbidly obese. This calculation isn't ideal, however, because it doesn't consider where the weight comes from, so individuals with large amounts of muscle mass may have BMI scores in the overweight or even obese range despite low levels of bodyfat. In addition, since BMI scores are not differentiated by gender, differences in body composition mean males are more likely to have high BMI scores than females.

Set Point TheorySet Point TheoryThe theory that the body has a genetically influenced weight it tends to maintain. suggests that people have different body weight set points which influence how many calories they are compelled to consume and their metabolism or how their bodies then burn or store those calories. Set point theory is still an oversimplification, however, because individuals who have had drastic changes to their body weights don't necessarily show corresponding changes to their metabolisms. A person's set point seems to be influenced by genes but early environment may also play a role, as illustrated by the “Dutch Hunger Winter”, or Hongerwinter, which occurred during the winter of 1944-1945 in Holland.

During this time Nazis successfully blockaded trade routes and millions of Dutch people starved for several months. The Dutch Famine Birth Cohort Study found that the children of women who were pregnant during the famine were more likely to suffer from type-II diabetes, cardiovascular disease, and obesity later in life. This suggests that this traumatic prenatal experience had lasting repercussions on their metabolisms, making their bodies less responsive to insulin and more likely to store fat. It seems that children of these children have been affected as well, which would be an example of an epigenetic change, or an environmental influence that causes changes which are then passed on to future generations.

Just as hunger signals provide important motivations to keep individuals alive, sexual motivations help to ensure the survival of the species via reproduction. In humans, sexual motivation is influenced by hormones including testosterone, estrogen, progesterone, oxytocin, and vasopressin. While hormone levels can influence sexual motivation, they don't directly regulate sexual behavior.

In many other species (but not humans), females undergo a period of estrus, or heat, during which they become fertile and are receptive to sexual advances from males. This window of sexual availability and fertility varies widely for different species, and may occur as often as once every few days (rats) or perhaps only once per year (pandas). Human females ovulate on a monthly cycle but this is not the sole precursor for sexual activity and women can engage in sexual behavior at any time during their cycle. In addition, human females “hide” their fertility, meaning that males cannot tell if a woman is ovulating by looking at her. Unlike the swollen bottoms of baboons or red chests of gelada monkeys which advertise estrus, human females don't have any obvious displays of when they are most fertile.

One proposed evolutionary explanation for this unpredictable timing of sexual desire combined with hidden fertility is that it encourages males to stick around. If a male can't be sure when a female is capable of becoming pregnant, he has an incentive to be around often to ensure paternity when the opportunity arises. If a male were certain that a female could not become pregnant for long periods of time, then he could leave during that time without the possibility of returning to raise offspring that are not his own. In evolutionary terms, this provides an advantage to the female because it helps to ensure that the male will be around to help provide resources for potential offspring, rather than being able to stray for months at a time.

Of course, if I were to ask people why they have sex, reproduction would not be the only answer. In fact, many people who have sex are hoping not to reproduce. So why are they doing it? One reason is that it feels good. Just as our genes encourage us to eat calorie-rich foods by making them taste great, we're driven to sexual behaviors not strictly for the noble cause of continuing the species but because sex just feels good. People also engage in sex for other reasons, including emotional intimacy, satisfying their partner, relieving stress, impressing friends, coping with negative emotions, or feeling more attractive.

In the 1960s, William Johnson and Virginia Masters set out to better understand sex, and recruited willing (and rather uninhibited) couples and individuals to come to the lab and have orgasms. Based on observation of over 10,000 orgasms, Masters and Johnson identified the stages of the human sexual response cyclesexual response cycleMasters and Johnson's description of sexual arousal in four phases: excitement, plateau, orgasm, and resolution., which were the same for males and females.

Masters and Johnson identified four physiologically distinct phases of the human sexual response cycle: excitement, plateau, orgasm, and resolution.

The cycle begins with the excitement phase, during which sexual arousal occurs. While the increased breathing and heart rate during the excitement stage suggests activation of the sympathetic nervous system, sexual arousal actually involves activation of the parasympathetic nervous system. Excessive stress and anxiety can cause problems with sexual arousal and may be responsible for erectile dysfunction in males or insufficient vaginal lubrication in females.

Arousal doesn't continue to rise indefinitely, and eventually reaches the plateau stage, where it remains high but relatively stable. As sexual activity continues, it reaches the orgasm stage, characterized by increased heart rate, involuntary muscle contractions and spasms, and feelings of euphoria.

The orgasm stage is followed by resolution, when heart rate and breathing return to a resting state. This stage is also characterized by a refractory period in males, during which further stimulation does not result in arousal.

While some may disagree, there's more to life than just food and sex; people are motivated to perform a wide variety of other behaviors. Abraham Maslow suggested that our motivations could be organized into a “hierarchy of needshierarchy of needsMaslow's pyramid of needs from physiological needs at the base to self-actualization at the top.”, meaning that some needs must be met before others, and we gradually move up the hierarchy. The most basic are physiological needs, for food, water, warmth, and sex. These exert powerful influence on an individual and need to be met before other needs can be considered. Once these are met, needs for safety and security follow, then needs for love and belonging, which include friendships, family, and intimacy. These are followed by needs for esteem, including self-esteem, freedom, independence, and a sense of self-respect. Finally, at the top of the pyramid, is the need for self-actualization. Self-actualization refers to a need to realize one's full potential as a person.

While Maslow's hierarchy does have an intuitive logic to it, the progression of needs may not be so clear-cut. We may consider hunger strikes and vows of abstinence as defiance of physiological needs in order to satisfy higher needs. Or we might consider altruistic acts where individuals risk their own safety in order to help others, or famines, where individuals who are starving share their food with friends and family, placing the need for community and social bonds before their own physiological needs. Maslow later suggested the possibility of a level higher than self-actualization: transcendence, where an individual is no longer concerned with personal needs, which could be used to explain such acts of altruism and self-sacrifice.

Motivations can be broadly categorized as intrinsic or extrinsic. Intrinsic motivationIntrinsic motivationMotivation driven by internal interest or enjoyment of the activity itself. refers to an internal sense of satisfaction and enjoyment from performing a task while extrinsic motivationextrinsic motivationMotivation driven by external rewards or to avoid punishment. refers to motivation driven by external rewards and punishments. In the chapter on learning theory we saw the behaviorist approach to understanding how rewards and punishments can encourage and discourage behavior, but we didn't see some of the ironic effects of rewards and punishments on motivation.

One such ironic effect was demonstrated in a study conducted by Mark Lepper, David Greene, and Richard Nisbett in 1973. Lepper, Greene, and Nisbett initially observed the amount of drawing behavior children engaged in during their free time at several nursery schools. Then children at some schools were told they would receive “Good Player” awards for drawing. Not surprisingly, this expected reward caused an increase in drawing behavior. What was surprising, however, was that when this reward was no longer offered, the increased interest in drawing didn't maintain itself, or even return to its previous baseline. Instead, drawing behavior decreased compared to the period before the reward was ever offered.

This is known as the overjustification effectoverjustification effectThe reduction in intrinsic motivation when external rewards are introduced for an already-enjoyable activity., in which extrinsic rewards come to replace intrinsic motivation. Essentially the children learned that one draws in order to get rewards, and so when those rewards are no longer available it seems there's no longer any reason to draw. Lepper, Greene, and Nisbett also had judges who were blind to the conditions of the experiment evaluate the quality of the artwork produced by children, and work produced during the “expected reward” period received the lowest ratings. This indicates that children weren't motivated by creativity and a sense of accomplishment, but instead were dashing off their “art” in order to get the reward.

An intuitive understanding of this overjustification effect may explain why many artists, musicians, or writers prefer to view their efforts as passions rather than as jobs for the sole purpose of earning money. A meta-analysis of 128 experiments by Edward Deci, Richard Koestner, and Richard Ryan in 1999 found that external rewards which are tangible (rather than verbal rewards or praise) could reduce intrinsic motivation. We should question rewards-for-grades programs that have been put into place in some school districts, which may cause students to see their learning as work, rather than a process of discovery which is rewarding for its own sake.

We can't rely on intrinsic motivation all the time of course, because sometimes we have to do things that we'd rather not do in order to get rewards later. In these cases, we must learn how to delay gratification, putting in effort now for benefits in the future. One measure of this ability is often referred to as the Marshmallow Test: children wait alone in a room with a marshmallow after being told they can eat it whenever they want but will get two marshmallows if they can wait until the researcher returns. This ability for self-imposed delay of gratification in 4 year-olds has been associated with higher ratings of social competence, better ability to cope with frustration, and even higher SAT scores (Mischel, Shoda, & Rodriguez, 1989).

Another ironic effect on motivation comes from punishment, in what we might call the “forbidden fruit” effect. In a study by Elliot Aronson and J. Merrill Carlsmith in 1963, children ranked several toys and then were threatened with either a mild punishment or a severe punishment for playing with a particular toy while the researcher left the room. When the researcher returned, the children ranked the toys again. It turns out that a mild threat of punishment reduced the desirability of that toy, but ironically, a severe threat increased its desirability. Aronson and Carlsmith suggested that the mild threat leads to insufficient justification for not playing with the toy. In other words, the children avoid the toy, but since the mild threat doesn't fully justify this avoidance, they also decide that the toy wasn't worth playing with in the first place and desirability is reduced. In the severe threat condition, however, the threat alone is enough to justify avoiding the toy but also serves to increase interest in the toy, making it more desirable. We may wonder how the threat of strict punishments for drug use, infidelity, or other transgressions may actually make these behaviors appear more desirable, perhaps revealing some truth to the expression “you always want what you can't have”.

It's not just threats of punishment that can ironically encourage behavior, it seems that actual punishments can also have this effect. Uri Gneezy and Aldo Rustichini (2000) found that day-care centers which began punishing parents with a fee for late pickups actually saw an increase in tardiness. This would likely leave B.F. Skinner scratching his head as to how a punishment could increase a behavior, but thinking in terms of motivation can help us understand what happened. Previously parents were intrinsically motivated to arrive on time in order to avoid feelings of guilt. Arriving late meant taking advantage of the teachers' time and violating a social norm. With the late fee in place, however, this intrinsic punishment was replaced by an extrinsic one, allowing parents to pay the fee rather than feel the guilt. Parents now knew the exact cost of arriving late, leading Gneezy and Rustichini to title their paper “A Fine is a Price”.

Given these ironic interactions, we might wonder which is better for managing behavior, intrinsic or extrinsic motivation? If you were managing a group of employees, for instance, would you focus on providing rewards and punishments for their efforts, or would you focus on their sense of satisfaction with the work they do? This relates to management theory, and managers can be broadly categorized based on which approach they prefer. Type X leaders focus on extrinsic motivators like benefits and punishments, while Type Y leaders focus on developing the intrinsic motivation of their workers. Similarly, we can divide leadership into task-oriented leadership, which focuses on actual tasks which need to be completed and relationship-oriented leadership, which focuses on the social goals of trust or cooperation within a group.

When we think about intrinsic and extrinsic motivations for behavior, we must also recognize that we may not always be conscious of motivations. If I asked you why you performed a particular behavior, you might be able to describe your motivation, but perhaps there are things going on under the surface that you aren't aware of. Since Freud's initial ideas about the psychodynamic unconscious, psychologists have considered the possibility of unconscious drives and motivations influencing behavior.

One such unconscious motivation proposed by Henry Murray and further researched by David McClelland was a need for achievement. This is a motivation to accomplish tasks, gain mastery, and win. Individuals with a high need for achievement may be motivated to seek out challenges of intermediate difficulty as tasks which are too difficult may lead to failure, while tasks which are too easy won't feel worthwhile or bring a sense of accomplishment.

You may recall Murray's name for his development of the Thematic Apperception Test, described in the previous chapter, in which participants provided storylines and character descriptions based on ambiguous situations. Murray believed that unconscious motivations could be revealed by an individual's responses to the TAT and that repeated themes of success, failure, and competition related to an individual's need for achievement.

David McClelland also suggested other unconscious needs and motivations, including a need for power and a need for affiliation. He suggested that motives were clusters of cognitions with emotional overtones that organize our behavior and our preferred experiences and goals. We can also see how our present environment influences our motivation for particular behaviors. McClelland referred to an external condition which creates desire for a particular behavior as a press, such as how seeing others receive honors can cause people to feel a greater need for recognition. You've probably also experienced a press if you are completely satisfied with a meal and don't feel any hunger, but then you see a dessert tray and are suddenly motivated to keep eating.

This brings us back to food, where the role of unconscious motivations can be seen in research by Brian Wansink which addresses environmental influences on eating behavior. We aren't simply relying on biological hunger signals or conscious decisions about how much to eat, and subtle cues like labels or plate size can have significant effects on how much food people eat. When people are asked why they ate a certain amount of food, they might be able to come up with a plausible explanation, but chances are there were also unconscious processes motivating some of their eating behavior. These cues can also be used to change eating habits for the better, so as Wansink notes in his book Mindless Eating, “The best diet is the one you don't know you're on”.

Another way of categorizing motivations is to consider them as either approach motivations or avoidance motivations. An approach motivationapproach motivationMotivation directed toward achieving positive outcomes. is a drive to experience a positive outcome, while an avoidance motivationavoidance motivationMotivation directed toward avoiding negative outcomes. is a drive to not experience a negative outcome. The relative strength of these motivations may not be equal and some research has suggested that motivations to avoid loss can overpower motivations for gains. In one study, Daniel Kahneman and Amos Tversky (1979) found that participants weren't willing to risk losing $8 on a coin flip, even if a win would pay $10. While rationally these odds favor playing, this demonstrates how we can be more strongly motivated to avoid a loss than gain a win.

These two types of motivation can work together or be in conflict. When we make decisions, we often have multiple options and we must do a sort of mental accounting of approach and avoidance motivations in order to choose. For instance, when making your weekend plans there might be two movies that you'd like to see. In this case, you have approach-approach conflict, because you want the positive experiences of both, but you can only choose one.

You might also experience avoidance-avoidance conflict when you are faced with choosing between outcomes which are all negative, such as deciding whether to wash the dishes or vacuum the floor.

Finally, you can have approach-avoidance conflict when a single choice contains both positive and negative motivations. For instance, imagine you've been invited to a party. You want to go because some of your friends are going (approach). At the same time, a few people you dislike will also be at the party, and you don't really want to interact with them (avoidance). Going to the party has positives you don't want to miss, but negatives that can't be avoided, so it's a situation where you're “damned if you do, damned if you don't”.

What's the relationship between goals and motivation? One area of goal setting relates to intrinsic and extrinsic motivation mentioned above. Is a goal driven by internal self-satisfaction, or an external reward? When goals are intrinsically motivated (known as self-concordant goals), individuals are more likely to persevere and they experience greater well-being when the goals are accomplished.

Even when goals are intrinsically motivated, however, we may still have trouble achieving them. One technique to help goal achievement is creation of implementation intentions. Rather than setting a goal and not knowing what to do next, you use if-then rules to create situations in which you will perform specific goal-directed behaviors.

For example, creating a rule that you will always review the previous week's psychology notes on Monday afternoons at 4pm creates a specific situation in which you will work on your goal (the goal of learning psychology well). This may help to maintain goal-pursuit even when motivation is lagging (if it's 4pm Monday then I review, even though I don't feel like it). Now on Monday afternoon you don't need to waste mental effort deciding which subject you should review or what time you should start.

Implementation intentions can also be used to ensure that you don't miss opportunities to make progress toward a goal. For example, creating the rule “If I'm waiting in line then I will use my flashcard app to review Spanish vocabulary” will help you take advantage of an opportunity to work on a goal that you might otherwise fail to notice. This doesn't mean you need to fill your day with rules for every situation, but I do recommend creating a few implementation intentions to help structure your time and ensure progress on your most important goals.