Biological Processes and Personality Chapter 7 PDF

Chapter 7 Biological Processes and Personality Learning Objectives 7.1 Examine Eysenck's theory that proposes that the brain processes underlie extraversion and neuroticism 7.2 Examine how the existence of a basic approach system would affect personality 7.3 Analyze how the existence of a basic...

Chapter 7 Biological Processes and Personality Learning Objectives 7.1 Examine Eysenck's theory that proposes that the brain processes underlie extraversion and neuroticism 7.2 Examine how the existence of a basic approach system would affect personality 7.3 Analyze how the existence of a basic avoidance system would affect personality 7.4 Examine how approach and avoidance systems are related to traits and temperaments 7.5 Explain how the assumption of a third basic system in personality can result in variation in restraint versus impulsiveness 7.6 Identify the influences of testosterone and oxytocin on personality 7.7 Describe the processes of electroencephalograms and neuroimaging as biological methods of assessing personality 7.8 Analyze how anxiety problems and antisocial behavior may be based in biology 7.9 Identify how progress in the biological process approach to personality depends on advances in other fields Lisa craves adventure. She always seems to be widening her circle of friends and activities. It's as though she needs the stimulation to keep her alive and happy. Her boyfriend shies away from it. All the noise and action are too much for him. He's more comfortable when things are less intense and he can plan his activities. Oddly enough, both feel their bodies are telling them what's best for them, even though "what's best" is quite different for one compared to the other. Humans are card-carrying members of the animal kingdom. We have all the characteristics implied by membership in that kingdom. We eat, drink, breathe, void wastes, and engage in the sexual activities that ensure the continuation of our species. How deeply rooted are these animal pressures? How pervasive is their influence on our day-to-day experiences? The biological process approach to personality assumes that human behavior reflects the operation of a complex biological system. The processes of this system reflect the way we're organized as living creatures. To understand how biological processes affect us, we have to start with the biological systems. What are they about, and how do they work? Then we can consider what those answers tell us about the kinds of phenomena identified with personality. This chapter takes the same starting point as did Chapter 6: the idea that personality is embedded in our bodies. Now, though, the focus is on the idea that personality is influenced by the workings of the body. Here, we consider some ideas about what the body is organized to do and think about how personality reflects these body processes. As in Chapter 6, there's room for people to be both similar and different. The similarities reflect the fact that everyone has a nervous system and an endocrine system. Those body parts have the same basic structure and functions from one person to another. The differences reflect (at least in part) the fact that parts of the nervous system and endocrine system are more active or more responsive in some people than in others. 7.1: Eysenck's Early Views on Brain Functions 7.1 Examine Eysenck's theory that proposes that the brain processes underlie extraversion and neuroticism One of the first modern attempts to link personality to biological functions was made by Hans Eysenck. Recall from Chapter 4 that Eysenck saw personality largely in terms of two supertraits: neuroticism and extraversion. He saw both of these as rooted in the body. Introverts are quiet and retiring; extraverts are outgoing, uninhibited, and immersed in social activity. Eysenck (1967, 1981) argued that this difference derives from differences in activation of the cerebral cortex. When the cortex is activated, the person is alert. When it's not, the person is drowsy. Eysenck proposed that introverts normally have higher cortical arousal than extraverts. This leads them to avoid social interaction, because it gets them overstimulated. Extraverts, with lower baseline levels, seek stimulation to bring their arousal up. Laboratory studies suggest that introverts may do better than extraverts at tasks that require the monitoring of slowly changing visual displays, as is required in the work of air traffic controllers. Some evidence fits the idea that introverts and extraverts differ in alertness. Consider vigilance tasks. They require you to be alert for specific stimuli. For example, you might have to listen to a long series of numbers and press a button whenever you hear three odd ones in a row. If your mind wanders, you miss some of what you're listening for. Introverts miss less than extraverts (Claridge, 1967). Another source of evidence is drug effects. If introverts are already alert, they shouldn't need as much of a stimulant to reach a given level of arousal. On the other side, introverts should need more of a depressant drug to reach a given level of unalertness. Both of these seem true (Claridge, 1967; Eysenck, 1983). Eysenck also proposed a neural basis for neuroticism. People who are high on this trait have easily aroused emotion centers. He thought this emotional arousal intensifies the manifestations of both extraversion and introversion---that is, it causes both to emerge more fully in behavior. This arousal causes both extraverts and introverts to become "more of what they are." Eysenck's effort to link personality to brain function was path-breaking. However, brain functioning is understood far better now than it was then. Changes in knowledge have elaborated and changed people's views of how brain functions and personality are interwoven. 7.2: Incentive Approach System 7.2 Examine how the existence of a basic approach system would affect personality Within the past 30 years or so, a number of theorists have proposed ideas about how the nervous system relates to personality. The ideas vary in focus. Some concern what parts of the brain are involved in certain kinds of actions. Some concern what brain chemicals are involved in certain kinds of actions. All take what might be called a functional approach. That is, they ask what functions particular kinds of behavior serve. The various types of behavior are then linked to ideas about brain processes, and both are linked to personality. We aren't going to give you a lesson in neuroscience here, but rather will focus on some of the functions that are proposed and how they're reflected in behavior and experience. Many people are working hard on this topic, and the literature is growing explosively. There are broad areas of agreement, but there are also disagreements. There's a lot of consensus about major themes, but there are also lots of ways to slice the pie. 7.2.1: Behavioral Approach Most theorists of this group believe that there's a set of brain structures involved when animals approach incentives: things they want. The structures involved in approach have been given several names: activation system (Cloninger, 1987; Fowles, 1980), behavioral engagement system (Depue, Krauss, & Spoont, 1987), behavioral facilitation system (Depue & Iacono, 1989), and behavioral approach system (BAS) (Gray, 1987, 1990, 1994a, 1994b). You might think of this system as regulating the psychological gas pedal, moving you toward what you want. It's a "go" system---a reward-seeking system (Fowles, 1980). This set of brain structures is presumed to be involved whenever a person is pursuing an incentive. It's likely that some more-specific parts of the brain are involved in the pursuit of food, others in the pursuit of sex, and others in the pursuit of shade on a hot summer day. But it's thought that those separate bits also link up to an overall BAS. Thus, the BAS is seen as a general mechanism to go after things you want. The BAS doesn't rev you up "in neutral," though, with no incentive in mind (Depue & Collins, 1999). It's engaged only in the active pursuit of things. The BAS is also held to be responsible for many kinds of positive emotions, such as hope, eagerness, and excitement, which can be seen as reflecting the anticipation of a reward. Evidence of this comes partly from studies of brain activity. One older way to study brain activity is to record electrical activity on the scalp (Davidson, 1988, 1992, 1995; Davidson & Sutton, 1995). Newer imaging techniques capture activity in other ways. While brain activity is being monitored, the people either are resting quietly or are exposed to stimuli. Examples are video clips or photos chosen to create specific kinds of emotional reactions. The question is which parts of the brain are more active in various situations. A variety of evidence suggests that incentives (and positive feelings) activate areas in the left prefrontal cortex. More left-prefrontal activity has been found in adults presented with incentives (Sobotka, Davidson, & Senulis, 1992), or positive emotional adjectives (Cacioppo & Petty, 1980), and in 10-month-olds viewing their mothers approaching (Fox & Davidson, 1988). Higher resting levels in this area predict positive responses to happy films (Wheeler, Davidson, & Tomarken, 1993). Higher resting levels in this area also relate to self-reported BAS sensitivity (Harmon-Jones & Allen, 1997; Sutton & Davidson, 1997) and to greater effort in pursuit of rewards (Hughes, Yates, Morton, & Smillie, 2014). Such findings led to the conclusion that a system based partly in the left prefrontal cortex is associated with tendencies to experience positive emotions and to pursue rewards. More recent techniques allow determination of individual differences in the sizes of brain regions. Those techniques have yielded evidence that extraverts have larger volumes of brain areas associated with approach, such as the medial orbitofrontal cortex (DeYoung et al., 2010). Since extraversion is often taken as a trait related to approach (McCabe & Fleeson, 2012), this fits a picture in which extraversion and approach may both reflect activity in those areas. 7.2.2: More Issues in Approach Recent evidence suggests that what underlies left-prefrontal activation is the approach process itself, rather than the positive feelings (Carver & Harmon-Jones, 2009; Harmon-Jones, Lueck, Fearn, & Harmon-Jones, 2006). Sometimes a desire to approach is thwarted. In this case, the approach system is engaged, but the emotions are frustration and anger. They feel negative, rather than positive. Several studies have linked such emotions to left-prefrontal activation and BAS sensitivity (for review, see Carver & Harmon-Jones, 2009). This evidence suggests that the core of left-frontal activation is the desire for reward, whether you're just about to get it (and you're happy) or whether someone has taken it away from you (and you're angry). Another project has linked BAS sensitivity to learning. Because the BAS responds selectively to incentives, BAS sensitivity should relate to learning involving positive outcomes but not to learning involving negative outcomes. In a study supporting this idea, a self-report measure of BAS sensitivity predicted speed at learning cues of reward in a conditioning task (Zinbarg & Mohlman, 1998). This scale did not relate to speed at learning cues of punishment. As noted earlier, there may also be specialized subsystems bearing on approach. Some evidence suggests that there may be social incentive systems, which overlap partially but not entirely with the more general approach system (Depue & Morrone-Strupinksy, 2005; Panksepp, 1998). Put differently, there may be specialized sensitivities to incentives within relationships. This idea has been supported in research on couples (Laurenceau, Kleinman, Kaczynski, & Carver, 2010). To sum up, people with reactive approach systems are highly sensitive to incentives, or to cues of good things about to happen. Those whose approach systems are less reactive don't respond as much (either behaviorally or emotionally) to such cues. For example, suppose two people have tickets to an upcoming concert by a band they like. Melanie gets excited just thinking about the concert (although it isn't until next week). Every time she does, she's ready to jump in the car. Melanie is very high in incentive reactivity, BAS sensitivity. Barbara, on the other hand, is more calm. She knows she'll enjoy the concert, but she's not so responsive to thoughts of potential reward. Barbara has less incentive reactivity. 7.2.3: Neurotransmitters and the Approach System Besides brain regions, the approach system has been tentatively linked to a specific neurotransmitter in the brain. A neurotransmitter is a chemical involved in sending messages along nerve pathways. There are many neurotransmitters, and they seem to have somewhat different roles. Several theorists have argued that a neurotransmitter called dopamine is involved in the approach system (Cloninger, 1988; Depue & Collins, 1999; Zuckerman, 1994). There are several ways to study dopamine function. One is to assess individual differences in dopamine reactivity using biomedical indicators of response to certain drugs. Another is to look at genes relating to dopamine function (see Chapter 6). In several studies, higher dopamine reactivity has been related to higher positive emotionality (Depue, 1995; Depue, Luciana, Arbisi, Collins, & Leon, 1994). Others have related dopamine to novelty seeking (Hansenne et al., 2002) and to several aspects of extraversion, including social dominance, enthusiasm, energy, and assertiveness (Depue & Collins, 1999). Research has also linked dopamine function to greater social dominance among monkeys (Kaplan, Manuck, Fontenot, & Mann, 2002). Others have suggested that high dopamine levels produce a flexible shifting among goals (Dreisbach & Goschke, 2004). Of course, what seems like flexible shifting of goals can also be seen as distractibility. Consistent with this, yet other evidence links high levels of dopamine to distractibility (Frank & O'Reilly, 2006). It's long been believed that dopamine is involved in reward-based learning (Frank & Claus, 2006; Holroyd & Coles, 2002). One current view is that bursts of dopamine in response to reward increase the learning (and the execution) of approach responses, and that dips in dopamine after nonreward increase the learning (and the execution) of avoidance responses (Frank, Seeberger, & O'Reilly, 2004). It may be, however, that the effect of dopamine is more on the performance than on actual learning. Studies of mice seem to show that they don't need dopamine to learn from reward. However, dopamine is necessary for the mice to want the reward and to seek it behaviorally (Berridge, 2007; Robinson, Sandstrom, Denenberg, & Palmiter, 2005; Wise, 2004). Some have concluded that dopamine is mainly about motivation, rather than learning---that is, that dopamine is involved in approach-related effort (Farrar et al., 2007; Salamone, Correa, Farrar, & Mingote, 2007). Others have looked at these effects from a different angle. Dopaminergic neurons respond intensely to unexpected rewards but less so to rewards that are expected. When a reward is expected but fails to occur, these neurons decrease responding (Schultz, 2000, 2006). This pattern seems to indicate that these neurons are involved in unexpected events of two kinds: better and worse than expected. That is, there's an increase in activity when an event is better than expected, no change when an event occurs as expected, and a decrease in activity when an event is worse than expected (Schultz, 2006). Some believe that that's how learning takes place: through detection of unexpected events. 7.3: Behavioral Avoidance, or Withdrawal, System 7.3 Analyze how the existence of a basic avoidance system would affect personality The previous section described an approach system. Most theorists also assume a somewhat distinct system in the brain that reacts to punishments and threats, rather than incentives. Some have labeled such a threat-based system an avoidance or withdrawal system (Cloninger, 1987; Davidson, 1988, 1992, 1995). Activity in this system may cause people to inhibit movement (especially if they're currently approaching an incentive) or to pull back from what they just encountered. You might think of this system as a psychological brake pedal---a "stop" system or a "throw-it-into-reverse" system. The avoidance system is responsive to cues of punishment and danger. When this system is engaged, the person may stop and scan for further cues about the threat, or the person may pull back. Since this is the system that responds to threats, dangers, and other to-be-avoided stimuli, it's also thought to be responsible for feelings, such as anxiety, fear, guilt, and revulsion. Once again, research on cortical activity is consistent with this general view. We said earlier that left-prefrontal areas are more active when people are happy. Right-prefrontal areas are more active when people are feeling anxiety or aversion---for example, when viewing film clips that induce fear and disgust (Davidson, Ekman, Saron, Senulis, & Friesen, 1990). Higher resting levels in that area predict more negative feelings when seeing such films, and they also relate to self-reports of threat sensitivity (Harmon-Jones & Allen, 1997; Sutton & Davidson, 1997). Findings such as these led Davidson and his colleagues to argue that anxiety relates to a behavioral withdrawal system, which involves the right prefrontal cortex. Research on learning has also examined the sensitivity of this system. Since this one is supposed to be reactive to punishments, not incentives, its sensitivity should relate to learning for negative outcomes, not positive ones. This prediction was confirmed by Zinbarg and Mohlman (1998), who found that threat sensitivity predicted speed at learning cues of punishment (but not cues of reward). Similar results were reported by Corr, Pickering, and Gray (1997). To sum up this section, people with reactive avoidance systems are sensitive to threat. This dimension reflects a trait of anxiety proneness. As an example of how it influences experiences, think of two people who just took a psychology test and suspect they did badly. Anxiety-prone Randy is almost in a panic about it, but Jessica, who is less anxiety prone, is bothered hardly at all. One of them is reacting emotionally to the sense of threat; the other isn't. Threat sensitivity and incentive sensitivity are thought to be relatively separate. People presumably differ from each other on both. As a result, all combinations of high and low approach and avoidance sensitivity probably exist. As an example, you might initially think of sociability as the opposite of shyness, but it's not (Schmidt, 1999). It's possible to be both drawn to social incentives (be very sociable) and also fearful of social interactions (be very shy). 7.3.1: Neurotransmitters and the Avoidance System As with reward sensitivity, people have tried to link threat sensitivity to a neurotransmitter. Here, there's less consensus. Serotonin has long been believed by some to be involved in anxiety or threat sensitivity (Cloninger, 1987; Handley, 1995; Lesch & Mössner, 1998). However, this view has been strongly challenged (Depue, 1995; Depue & Spoont, 1986; Panksepp & Cox, 1986; Soubrié, 1986; Zuckerman, 2005). The dispute isn't over, and the evidence is complex. Our own interpretation of it, however, suggests that serotonin's main influence lies elsewhere (Carver & Miller, 2006; Carver, Johnson, & Joormann, 2008). We return to this issue later on. Another candidate for involvement in anxiety is gamma-aminobutyric acid, more commonly known as GABA (Roy-Byrne, 2005). There's some research linking sensitivity of GABA receptors to neuroticism (Glue, Wilson, Coupland, Ball, & Nutt, 1995). However, most of what is known on this topic comes from studies of anxiety disorders. In fact, most of the studies focus specifically on panic disorder (Zwanzger & Rupprecht, 2005). People with panic disorder have relatively low levels of GABA (Goddard et al., 2001). Treatments that increase GABA reduce the symptoms of panic patients (Zwanzger & Rupprecht, 2005). Yet another likely contributor to the biology of threat is norepinephrine. Norepinephrine is produced in response to stress (Morilak et al., 2005), and it has been linked to panic reactions (Bailey, Argyropoulis, Lightman, & Nutt, 2003). Research has also shown that problems in regulating norepinephrine relate selectively to anxiety disorders (Cameron, Abelson, & Young, 2004). This finding seems to link this chemical specifically to threat sensitivity. 7.4: Relating Approach and Avoidance Systems to Traits and Temperaments 7.4 Examine how approach and avoidance systems are related to traits and temperaments Let's stop and look at what we've said thus far in the chapter. Many theorists converge on the idea that one brain system manages approach of incentives and another manages withdrawal from threats. The one that manages approach also creates excitement and enthusiasm. The one that manages withdrawal creates fear or anxiety. How do these ideas fit with ideas from previous chapters? Quite well, in fact. The avoidance system links easily to the trait of neuroticism. As noted earlier, anxiety is at its core. Larsen and Ketelaar (1991) found that neuroticism predicts susceptibility to a manipulation of anxiety; Carver and White (1994) found the same effect for a measure of threat sensitivity. In sum, neuroticism and threat sensitivity have a great deal in common (see also Elliot & Thrash, 2002). In fact, there's little doubt that the brain system we've been describing regarding avoidance is critical to neuroticism. Indeed, there is evidence that the brain areas believed to be important in threat responses covary in volume with neuroticism (DeYoung et al., 2010). As noted in Chapter 6, developmental theorists have also posited an avoidance temperament (e.g., Derryberry & Rothbart, 1997; Eisenberg, 2002; Eisenberg et al., 2004; Kochanska & Knaack, 2003; Rothbart, Ahadi, & Evans, 2000; Rothbart, Ahadi, Hershey, & Fisher, 2001; Rothbart & Bates, 1998; Rothbart & Posner, 1985). Again, there is a good fit. With respect to approach, there appears to be a link between the approach system and extraversion. Fitting these two together is a bit trickier than matching neuroticism to avoidance, partly because theorists differ about what defines extraversion. Definitions usually include a sense of activity and agency (Morrone, Depue, Scherer, & White, 2000). Extraversion also suggests a preference for being with others, or sociability (Depue & Morrone-Strupinsky, 2005). Sometimes, there's a quality of social dominance or potency (Depue & Collins, 1999). All definitions seem to include a tendency to experience positive emotions. These various extraversion packages resemble BAS function fairly well. There is also evidence that extraversion relates to the volume of brain areas associated with approach, such as the medial orbitofrontal cortex (DeYoung et al., 2010). As noted in Chapter 6, contemporary developmental theorists also assume an approach temperament. Measures of extraversion correlate with measures of approach sensitivity (Carver & White, 1994). Zelenski and Larsen (1999) found that measures of extraversion and BAS constructs were all interrelated, and as a set, they predicted positive feelings. Extraverts are responsive to positive mood manipulations (Larsen & Ketelaar, 1991); those high in BAS sensitivity also have positive feelings to impending reward (Carver & White, 1994). Thus, there's a good deal of consistency. 7.4.1: The Role of Sociability Still, when fitting extraversion to approach sensitivity, there are a couple of areas of uncertainty. Table 7.1 lists several theorists who have written about extraversion. The table also lists some qualities the theorists see as belonging to these traits. As you can see, there are two qualities for which differences of opinion arise. Table 7.1 Several theorists and qualities they believe belong to extraversion (and alternative traits closely related to extraversion). All incorporate pursuit of incentives and a tendency to experience positive emotions. Many, though not all, include a quality of sociability. A couple have also included impulsiveness.  One of them is the social quality that's usually considered part of extraversion. That quality is missing from Gray's view of the BAS. In fact, Gray ignored sociability altogether. One way to resolve things would be to view BAS sensitivity as sensitivity to social incentives. Given that humans are a very social species, it might make sense to think of human approach primarily in terms of approaching social interaction. As noted earlier in the chapter, however, some theorists think there's a separate approach subsystem that's specialized to regulate social approach. Perhaps extraversion actually is a blend of overall BAS sensitivity and social-specific BAS sensitivity. On the other hand, several projects seem to suggest that sociality per se is not the core of extraversion. One of these projects, mentioned in Chapter 4 (Lucas, Diener, Grob, Suh, & Shao, 2000) concluded that the core of extraversion is reward sensitivity and the tendency to experience positive affect. Lucas and Diener (2001) found extraverts were drawn to situations that offered opportunities for rewarding experiences, whether social or nonsocial. Other research has shown that extraverts are not more responsive to pleasant stimuli in general, but only to appetitive stimuli---those associated with approach motivation and reward (Smillie, Cooper, Wilt, & Revelle, 2012). Recent brain research also seems to suggest a larger role for approach than sociality (Grodin & White, 2015). 7.4.2: The Role of Impulsivity The second issue on which conceptualizations of extraversion have differed concerns impulsivity. In this case, however, the argument may be dying down. Gray used the word impulsivity to mean approach sensitivity, but it was an unfortunate choice, as he didn't seem to have issues of impulse control in mind. Eysenck included impulsiveness in extraversion for years, but then he moved it, because it consistently related better to psychoticism. Depue and Collins (1999) said that impulsivity with positive affect (the key to extraversion) belongs in extraversion but that impulsivity without positive affect doesn't. Relevant to this issue is the study by Zelenski and Larsen (1999) mentioned earlier. They factor analyzed several personality measures, including measures of impulsivity, threat sensitivity, and incentive sensitivity. They found that measures of impulsivity loaded on a different factor than did extraversion (which loaded on the BAS factor). Also relevant to this issue is evidence from research with monkeys. One study (Fairbanks, 2001) found that social dominance, which many see as part of extraversion, relates to moderate impulsivity---not high or low. On the whole, evidence suggests that impulsivity does not belong in extraversion. Where, then, does it belong? 7.5: Sensation Seeking, Constraint, and Effortful Control 7.5 Explain how the assumption of a third basic system in personality can result in variation in restraint versus impulsiveness Many people believe that there's at least one more broad biologically based dimension of personality. It has had several labels, but in each case, it has incorporated a quality of planfulness versus impulsivity. One label for this dimension is sensation seeking. Marvin Zuckerman (e.g., 1985, 1991, 1992, 1993, 1994, 2005) and his colleagues have studied this quality extensively. 7.5.1: Sensation Seeking People high in sensation seeking want new, varied, and exciting experiences. Compared to other people, they are faster drivers (Zuckerman & Neeb, 1980), more likely to use drugs (Zuckerman, 1979), to increase alcohol use over time (Newcomb & McGee, 1991), to do high-risk sports such as skydiving (Hymbaugh & Garrett, 1974), and to engage in risky antisocial behaviors (Horvath & Zuckerman, 1993). They are more sexually experienced and sexually responsive (Fisher, 1973), and when in relationships, they are more dissatisfied (Thronquist, Zuckerman, & Exline, 1991). When serving in the army, they are more likely to volunteer for a combat unit (Hobfoll, Rom, & Segal, 1989). Sensation seekers like to pursue new, varied, and exciting experiences. We said earlier that theorists of this group tend to use a functional approach---that is, they look for the purpose a given system might serve. What might be the function of sensation seeking? An early view was that this dimension regulates exposure to stimulus intensity (Zuckerman, 1979, 1991, 1994). High sensation seekers open themselves to stimulation; low sensation seekers protect themselves from it. Both tendencies have advantages and disadvantages. People high in sensation seeking should function well in overstimulating conditions, such as combat, but they may display antisocial qualities in situations that are less demanding. People lower in sensation seeking are better adapted to most circumstances of life, but they may "shut down" psychologically when things get too intense. A broader view of this trait's function relates it to the demands of social living. Zuckerman (1991, 1993) calls impulsive unsocialized sensation seeking (IUSS) a deficit in the capacity to inhibit behavior in service of social adaptation. IUSS relates inversely to sociability and positively to aggressiveness (Zuckerman, 1996; Zuckerman, Kuhlman, Joireman, Tetar, & Kraft, 1993). It's been implicated in antisocial personality disorder (Krueger et al., 1994; Rowe, 2001; Zuckerman, 1994). It seems to involve a focus on the immediate consequences of behavior, rather than longer-term consequences (Joireman, Anderson, & Strathman, 2003). All of these qualities seem to reflect, in part, qualities of impulse versus restraint. 7.5.2: Relating Sensation Seeking to Traits and Temperaments How do these ideas fit with ideas from previous chapters? There are strong links to several trait models, discussed in Chapter 4. IUSS relates inversely to both agreeableness and conscientiousness of the five-factor model (Zuckerman, 1996) and to constraint from Tellegen's (1985) model (constraint is virtually the opposite of IUSS). Recall that low levels of these traits relate to problems in getting along in life. IUSS also relates to psychoticism in Eysenck's model, which concerns disregard of social restraint in pursuit of intense sensations. In Chapter 6, we noted that properties related to impulsivity have also been discussed as a temperament (e.g., Rothbart et al., 2000; Rothbart et al., 2001; Rothbart, Ellis, Rueda, & Posner, 2003; see also Eisenberg, 2002; Eisenberg et al., 2004; Kochanska & Knaack, 2003). The temperament called effortful control bears a good deal of resemblance to IUSS. It's about being focused and restrained, and it implies planfulness and awareness of others' needs. High levels of this temperament early in life predict fewer problems with antisocial behavior later on (Kochanska & Knaack, 2003). This temperament is slower to emerge than the approach and avoidance temperaments and may not be fully operative until adulthood (Casey, Giedd, & Thomas, 2000). It's believed to relate to the part of the brain that manages executive functions: the prefrontal cortex. In making comparisons to these trait and temperament models, one more thing is worth noting. In each case, the trait under discussion is distinct and separate from the traits relating to extraversion and neuroticism (or approach and avoidance sensitivities). Depue and Collins (1999) reviewed 11 studies in which two or more personality inventories were jointly factor analyzed. All identified a distinct higher-order trait reflecting impulse versus constraint. 7.5.3: Another Determinant of Impulse and Restraint If there were only an approach and an avoidance system, the balance between them would determine what one does (Figure 7.1, A). A person with strong appetites and little fear will approach impulsively (Arnett, Smith, & Newman, 1997; Avila, 2001); a person with weak appetites and strong fear won't. Figure 7.1 Another determinant of action and restraint. (A) Approach and avoidance temperaments compete for influence over behavior; impulsive approach occurs if the approach process outweighs the avoidance process. (B) Effortful control can countermand whichever of those temperaments is presently dominating and exert its own effect on the direction of behavior.  Figure 7.1 Full Alternative Text The addition of a third system for effortful control (Figure 7.1, B) creates greater complexity. Now it's not entirely a matter of the balance between approach and avoidance. Effortful control has an influence over both of these. It can help people hold back from doing something they want to do, like taking that third piece of cake. It can help people pass over a short-term benefit to get larger benefit later on. Effortful control also helps people do things they don't want to do, such as look happy when they get a gift they don't really like (Kieras, Tobin, Graziano, & Rothbart, 2005). These influences on behavior need not involve fear at all. Interestingly, a study of brain responses among persons high and low in sensation seeking found support for the view that highs have both especially strong approach reactions and relatively weak self-control over such responses (Joseph, Liu, Jiang, Lynam, & Kelly, 2009). 7.5.4: Neurotransmitters and Impulse versus Constraint Is a particular brain chemical tied to impulse versus constraint? Zuckerman (1994, 1995) suggested a role for monoamine oxidase (MAO), which helps regulate several neurotransmitters. MAO levels relate to personality traits such as sensation seeking and novelty seeking (Ruchkin, Koposov, af Klinteberg, Oreland, & Grigorenko, 2005; Zuckerman, 1994). MAO also relates to dominance, aggression (Rowe, 2001; Zuckerman, 1995), and drunk driving (Paaver, Eensoo, Pulver, & Harro, 2006). Genes related to MAO levels have been linked to aggression and impulsivity (Manuck, Flory, Ferrell, Mann, & Muldoon, 2000; Raine, 2008). Maybe MAO is one key to this system. On the other hand, some researchers consider MAO level to be mostly an indicator of the activity of neurons of the serotonin system (Oreland, 2004). Perhaps the key actually lies in serotonin function. There is, in fact, a good deal of evidence linking low serotonergic function to impulsivity (reviewed by Carver et al., 2008; see also Carver, Johnson, Joormann, Kim, & Nam, 2011). Much of the research assesses serotonergic function by responses to certain drugs (see Box 7.1). Sometimes, serotonin function is even manipulated. Box 7.1 Research Question: How Do You Measure Neurotransmitter Function? Researchers are now studying the role of neurotransmitters in a wide range of behavior. This requires a way to measure neurotransmitter functions in research participants. How is this done? It's more complicated than testing for how much of that neurotransmitter is lying around in the person's brain. What's actually at issue is how the neurotransmitter is being used. Consider serotonin as an example. Serotonin receptors vary in sensitivity (as do all receptors for neurotransmitters). If someone has a chronically low serotonin level (call him Eddie), the receptors will adjust to become more sensitive. If someone has a chronically high serotonin level (call him Phil), the receptors will adjust to become less sensitive. Because Eddie's receptors are now very sensitive, they can do their work with relatively little serotonin. Because Phil's receptors are now relatively insensitive, they will respond less to the same amount of serotonin. Phil needs more serotonin to have the same processing effect. Eddie has very responsive serotonin functioning, whereas Phil's functioning is less responsive. The responsiveness of a neurotransmitter system in humans is sometimes assessed by testing the system's ability to regulate itself. This is done by giving a drug that disrupts the system's stable state. The question then is how big a response occurs. For example, a drug called fenfluramine causes serotonin to be released from storage areas and also inhibits its reuptake. Thus, it causes an increase (lasting several hours) in the level of serotonin available for use. Receptors elsewhere in the brain sense this increase in serotonin and cause the pituitary gland to release prolactin. This eventually helps bring the serotonin level back down, but it takes a while. Prolactin concentrations are easy to measure. Researchers track the prolactin level and determine its peak increase over a period of three to five hours after the fenfluramine is taken. That peak prolactin response (the increase over baseline) is an index of how responsive the serotonin system is (Manuck, Flory, Ferrell, Mann, & Muldoon, 2000). A large rise in prolactin means a sensitive or responsive serotonin system. In one such study, experimentally lowering serotonin led to greater hostility and aggressiveness among persons who were already high in aggressive tendencies, but it didn't do anything among persons lower in aggressiveness (Cleare & Bond, 1995). In a later study, lowering serotonin created higher aggressiveness among highly aggressive men but had the opposite effect among those low in aggressiveness (Bjork, Dougherty, Moeller, & Swann, 2000). These findings suggest that low serotonin function made people act more the way they tend to be anyway. That would fit with the idea that low serotonin means loosening restraint of one's basic tendencies. Another source of information is cross-sectional studies linking qualities of personality to serotonergic function. Many of these studies focus on patient samples, typically comparing patients to controls. A popular group for this kind of study is people who display impulsive aggression. A good number of studies have related lower serotonergic function to a history of fighting and assault (Coccaro, Kavoussi, Cooper, & Hauger, 1997), domestic violence (George et al., 2001), and impulsive aggression more generally (Cleare & Bond, 1997). Although there's a lot of evidence linking low serotonergic function to aggressiveness, most researchers seem to believe that the link is more directly to impulsiveness in reacting to emotion than to hostility per se. Studies have also examined personality and serotonergic function among nonclinical samples. Several early studies (Cleare & Bond, 1997; Depue, 1995; Netter, Hennig, & Rohrmann, 1999) found relations between low serotonergic function and elevated aggression-hostility traits, similar to the findings just described. Depue (1995) also found links from low serotonergic function to the impulsivity facet of Tellegen's constraint scale, the aggression facet of Tellegen's negative emotionality scale, to two sensation-seeking subscales, and to several indices of impulsiveness. Depue also looked more closely at hostility and found the strongest relations of low serotonergic function to subscales reflecting impulsive, action-oriented aggression. A more recent study produced similar results (Hennig, Reuter, Netter, Burk, & Landt, 2005). Other research has had a broader focus. Several studies have been done using personality inventories, sometimes along with other measures. One of them (Manuck et al., 1998) used the NEO-PI-R plus additional measures in a community sample. All effects that emerged did so only among men. Low serotonergic function related to greater life history of aggression and impulsiveness, consistent with previous results. Low serotonergic function also related to higher neuroticism (from the NEO-PI-R) and the neuroticism facet angry hostility. High serotonergic function related to higher conscientiousness (from the NEO-PI-R). There's also one more interesting twist to the evidence. Zald and Depue (2001) argued that serotonin should inhibit positive reactions as well as negative. To test this, they had men track their emotions for two weeks. Then they computed averages separately for positive and negative feelings and related them to the men's levels of serotonergic function. Higher serotonergic function related to less negative affect, consistent with the findings just reviewed. However, higher serotonergic function also related to lower levels of positive feelings (interested, active, attentive, and enthusiastic). Thus, serotonin may provide a constraining influence over the biological systems that manage affects of both sorts. The pattern from this research as a whole seems consistent with the view that serotonergic pathways are involved in impulse control (Depue, 1995; Depue & Collins, 1999; Depue & Spoont, 1986; Manuck, Flory, Muldoon, & Ferrell, 2003; Soubrié, 1986; Zuckerman, 2005). Furthermore, it appears to be consistent with a view in which the resulting restraint (when it does occur) is effortful, rather than an involuntary reaction. 7.6: Hormones and Personality 7.6 Identify the influences of testosterone and oxytocin on personality We turn now to a different part of the biological process view on personality: the relationship between hormones and personality. An important group of hormones is sex hormones. We won't explore all the ways sex hormones influence behavior, but we'll examine a few of them, focusing primarily on testosterone. 7.6.1: Hormones, the Body, and the Brain From very early in life, sex hormones are important in several ways. Normal males have higher testosterone than normal females from week 8 to week 24 of gestation, from about the first through the fifth month after birth, and again after puberty (Le Vay, 1993). Testosterone differences in gestation are essential to changes in the nervous system that create normal male and female physical development. Many researchers believe that the hormones also change the brain in ways that result in behavioral differences (Breedlove, 1994; Le Vay, 1993). The basic template for a human body is female. Only if hormones cause specific changes to occur does a body emerge that looks male. If a genetic male isn't exposed to androgen ("male-making") hormones at critical points in development, the result will be an exterior that looks female. If a genetic female is exposed to testosterone at the same points, the result will be an exterior that looks male (Breedlove, 1994). During normal fetal development, only males are exposed to enough androgen to be masculinized. The hormones that guide the body in its sexual development also affect nerve cells (Breedlove, 1992; Le Vay, 1993). They organize the developing brains of males and females differently, in subtle ways (Cohen-Bendahan, van de Beek, & Berenbaum, 2005). Animal research suggests there aren't just two patterns but a broad range of variation, with male and female patterns as the extremes (Panksepp, 1998). The genders tend to differ in linkages among synapses and in the size of some brain structures. For example, the two sides of the cortex are more fully interconnected in women than men (Le Vay, 1993). Interestingly, there's evidence that the brains of gay men structurally resemble those of women more than those of heterosexual men (Allen & Gorski, 1992; Le Vay, 1991). How might these differences in the nervous system relate to personality? We said earlier that exposure to androgens masculinizes the nervous system. Several things may follow from this. 7.6.2: Early Hormonal Exposure and Behavior Early exposure to hormones, even prenatal exposure, can influence later behavior. One early study (Reinisch, 1981) looked at children whose mothers had received synthetic hormones while being treated for complications in their pregnancies. Those hormones act somewhat like testosterone. Each child thus was exposed to the hormones prenatally during a critical phase of development. The other group was the children's same-sex siblings (to match as closely as possible on genetic and environmental variables). An average of 11 years after exposure, each child completed a self-report measure in which six situations were described, each involving interpersonal conflict. The children made decisions about what they would do in each situation. Of interest was the likelihood of responding with physical aggression. The study yielded two separate effects, both bearing on the choice of physical aggression as a response to conflict (see Figure 7.2). The first was a sex difference: Boys chose this response more than girls did. There was also an effect of prenatal exposure to the hormone. Children who had been exposed chose physical aggression more than children who hadn't been exposed. This was true both for boys and for girls. Figure 7.2 Average (self-report) physical aggression scores during childhood for boys and girls who had been exposed to synthetic hormones before birth and for their sex-matched siblings who had not been exposed. Exposure to the hormone produced elevated aggression scores for both boys and girls. Figure 7.2 Full Alternative Text This study is intriguing for a couple of reasons. It's clear that a biological variable---the hormone---influenced the behavior. It's less clear how it did so. Animal research indicates that exposure to male hormones during early development increases aggressive displays (Reinisch, 1981). But this study didn't measure aggressive action, just self-reports indicating the choice of aggression. Thus, any masculinizing influence on the nervous system had to filter through a lot of cognition to be displayed. In another project, Berenbaum and Hines (1992) studied children with a genetic disorder that causes high levels of masculinizing hormones prenatally and soon after birth. Years later (ages 3 to 8), these children (and unaffected same-sex relatives) were observed as they played individually. Available to them were toys that had been determined to be generally preferred by boys and by girls. The question was who would play with which toys. The androgen-exposed girls spent more time with the boys' toys and less time with the girls' toys than did unexposed girls (see Figure 7.3). In fact, they displayed a preference pattern like that of boys. Figure 7.3 Amount of time two groups of girls played in a free-play setting with toys generally preferred by boys and toys generally preferred by girls. Some of the girls had been exposed to masculinizing hormones before birth and shortly afterward; the others had not been exposed.  Figure 7.3 Full Alternative Text Androgens come from several sources. Exposure through a mother's medical treatment during pregnancy is one. Another is the adrenal glands, which secrete androgen. High levels of natural androgen in girls have been related to greater involvement in sports that involve rough body contact (Kimura, 1999), activities that are more typical of boys. Another study found that higher levels of naturally occurring fetal testosterone predicted lower levels of empathy at age 4 (Knickmeyer, Baron-Cohen, Raggatt, Taylor, & Hackett, 2006). The findings are somewhat mixed, but they appear generally consistent with the idea that early exposure to masculinizing hormones can influence behavior. It can increase the potential for aggression, lead to preference for masculine toys, and enhance boldness. 7.6.3: Testosterone and Adult Personality A good deal more research on sex hormones and personality examines how current levels of testosterone relate to behavior. It also implicates testosterone in regulating important qualities of behavior. James Dabbs and his colleagues conducted much of the pioneering research on this topic (see Dabbs & Dabbs, 2000). Testosterone is a sex hormone, but research on its behavioral effects has focused more on dominance and antisocial behavior than sexual behavior. One study of men in prison (Dabbs, Frady, Carr, & Besch, 1987) found that inmates high in testosterone had violated prison rules more often and were more dominant than those lower in testosterone. They were also more likely to have committed violent crimes. Similar results have come from female inmates (Dabbs, Ruback, Frady, Hopper, & Sgoutas, 1988). In a sample of men who had committed murder, those high in testosterone were more likely to have planned the act ahead of time and to have killed people they knew (Dabbs, Riad, & Chance, 2001). Recent research suggests a link between testosterone level and aggression. Another study examined testosterone and antisocial behaviors in military veterans (Dabbs & Morris, 1990). Men higher in testosterone had larger numbers of sex partners and were more likely to abuse alcohol and other drugs. They were more likely to have gone absent without leave in the military and to have assaulted others. They were also more likely to have had trouble with parents, teachers, and classmates while growing up (see also Box 7.2). These effects were strongest, by far, among men of low socioeconomic status (SES). Box 7.2 Steroids: An Unintended Path to Aggression Discussing the effects of testosterone on behavior brings up a related topic: bodybuilding. Guys are drawn to bodybuilding partly because of its result: a body that looks chiseled from rock. Cultural expectations of men's bodies (as reflected in Playgirl photos) have shifted over decades, becoming increasingly dense and muscular (Leit, Pope, & Gray, 2001). These expectations create pressure on men to look that way. The desire for a well-formed body leads many people to use anabolic steroids. The word anabolic means "building up." Anabolic steroids are chemicals that prompt the body to rebuild muscle tissue that has been stressed or exercised. Your body naturally gives you small doses of such chemicals, producing growth in muscle size. Using steroids gives you a much bigger dose. Steroids thus let you speed up and exaggerate the building of muscles to a degree that exercise alone cannot do. That's why people use steroids. In a survey of male gym users, 18% said they used adrenal hormones, 25% used ephedrine, and 5% used anabolic steroids (Kanayama, Gruber, Pope, Borowiecki, & Hudson, 2001). Indeed, some people use steroids and steroidlike substances without fully realizing it. So-called dietary supplements, which many people use, often are potent drugs. Many users don't realize that steroids are synthetic hormones. Steroids are related to testosterone (that's why men's muscles tend to be larger than women's). Testosterone is involved in many things, not just building muscles. Consequently, people who use steroids to produce larger muscles are in for a surprise: There can be unintended and unpleasant side effects. Some of these effects are physical. If you're a man, part of your body sees the steroids as testosterone. It reacts to what looks like too much testosterone by shutting down the production of more. The results are a lowered sperm count and a decreased sex drive. (The steroids don't act like testosterone in these respects.) If you're a woman, taking steroids causes masculinizing effects: shrinking breasts, a deepening voice, and an increase in facial and body hair (Gruber & Pope, 2000). Steroids also have behavioral effects, which are of particular interest here. As noted in the main text, testosterone is linked to dominance and aggressiveness. Steroids do much the same (even among hamsters!; Grimes, Ricci, & Melloni, 2006). Because the doses tend to be large, so are the effects. Heavy steroid use can yield irrational bursts of anger, popularly referred to as "roid rages." Adverse responses aren't limited to men, either. Among women users, 56% reported manic symptoms during steroid use, and 40% reported depressive symptoms during steroid withdrawal (Gruber & Pope, 2000). Evidence from animal research suggests that steroid use during adolescence can create aggressive tendencies that remain long after the steroid has been withdrawn (Harrison, Connor, Nowak, Nash, & Melloni, 2000). These effects are bad enough in the average person. But it's not only the average person who does bodybuilding and uses steroids. Bodybuilding has considerable appeal to people who already have a strong streak of dominance and aggressiveness. Add steroids to an already aggressive personality, and the result is a potential for serious violence. Not only can having low SES increase the ill effects of high testosterone, but high testosterone tends to lead men into lower-SES lives (Dabbs, 1992a). This seems to occur because high testosterone promotes antisocial behavior and disruption of education. Both factors then lead people away from white-collar occupations. Differences in testosterone relate to occupations in other ways, as well, fitting a link between testosterone and social dominance (Mazur & Booth, 1998). For example, trial lawyers (of both genders) are higher in testosterone than nontrial lawyers (Dabbs, Alford, & Fielden, 1998). Actors and professional football players have high levels of testosterone (Dabbs, de La Rue, & Williams, 1990), and ministers have low levels. (College professors, if you must know, are in the middle.) Why are actors so different from ministers? After all, they're both on stage. Dabbs et al. (1990) suggested that actors must be dominant constantly, because their reputation is only as good as their last show. Ministers are in a framework that tolerates more variability. Furthermore, the actor's role is to seek and hold onto glory, whereas the minister's role is to be self-effacing. Effects of testosterone occur in many small ways that are related to social potency and dominance. In one study, testosterone related to deeper voices among men (Dabbs & Mallinger, 1999). In studies of brief interactions with strangers, participants higher in testosterone entered more quickly, focused more directly on the other person, and displayed more independence and confidence than those with less testosterone (Dabbs, Bernieri, Strong, Campo, & Milun, 2001). Men who think of themselves as dominant and emit more dominance displays are also high in testosterone (Slatcher, Mehta, & Josephs, 2011), but testosterone increases dominance displays even when the challenge occurs outside awareness (Terburg, Aarts, & van Honk, 2012). Even young children are influenced by testosterone. Those high in testosterone are more independent on the playground than those with lower testosterone (Strong & Dabbs, 2000). The role of testosterone in dominance is displayed in other ways, as well. What happens if people low in testosterone are put into positions of high status? What happens if people high in testosterone are put into positions of low status? In both cases, they become upset and perform poorly (Josephs, Sellers, Newman, & Mehta, 2006). When the situations are reversed, however, everyone feels better and performs better. The dominance that's linked to high testosterone is useful in many contexts, but it can interfere with relationships. Booth and Dabbs (1993) found that men with higher testosterone were less likely to have married. If they did marry, they were more likely to divorce. They were also more likely to have had extramarital sex and to commit domestic abuse. Men high in testosterone have smiles that are less friendly than those of men lower in testosterone, and they express more dominance in their gaze when in conversation (Dabbs, 1992b, 1997). Members of low-testosterone fraternities are friendly and smile a lot, whereas members of high-testosterone fraternities are more wild and unruly (Dabbs, Hargrove, & Heusel, 1996). Several studies have related testosterone to personality. In two studies, personality data and testosterone data were factor analyzed (Daitzman & Zuckerman, 1980; Udry & Talbert, 1988). In both cases, a factor formed around testosterone, with overtones of impulsiveness, sensation seeking, and dominance. The factor included these self-ratings: cynical, dominant, sarcastic, spontaneous, persistent, and uninhibited. This pattern of characteristics also appears to relate back to work on brain functions and impulsivity, discussed earlier in the chapter. 7.6.4: Cycle of Testosterone and Action It may be most obvious to think about testosterone in terms of stable individual differences. However, testosterone is also part of a dynamic system that changes over time and events (Dabbs, 1992b). Levels of testosterone shift in response to social situations of several types. These shifts may, in turn, influence the person's later behavior. Testosterone rises after positive experiences. As shown in Figure 7.4, it rises after success at a competitive event (Mazur, Booth, & Dabbs, 1992) and falls after a failure or humiliation. It rises when your team wins and falls when your team loses (Bernhardt, Dabbs, Fielden, & Lutter, 1998). It also rises, though, when you are confronted with an insult (Nisbett & Cohen, 1996). It rises (for both men and women) after sexual intercourse (Dabbs & Mohammed, 1992). It goes up among men skateboarding in front of an attractive woman (Ronay & von Hippel, 2010). Even fooling around with a gun for a few minutes can make testosterone increase (Klinesmith, Kasser, & McAndrew, 2006).  Figure 7.4 Full Alternative Text Such changes in testosterone also have implications for subsequent behavior. Increases in testosterone make people more sexually active (Dabbs, 1992b). An increase in testosterone can also make a person seek out new competition and chances to be dominant (Mazur, 1985; Mazur et al., 1992). It makes people more responsive to possible rewards and less responsive to possible losses (van Honk et al., 2004). It makes them less empathic (Hermans, Putman, & van Honk, 2006) and less able to detect anger on another person's face (van Honk & Schutter, 2007). A decrease in testosterone after a failure may cause a person to be less assertive and avoid new competition. Thus, in either case (success or failure), there's a tendency toward a spiraling effect: A given outcome tends to promote more of the same outcome. 7.6.5: Testosterone, Dominance, and Evolutionary Psychology Let's step back from these studies to consider a broader implication. The findings, as a group, seem to fit with one of the themes of evolutionary psychology, discussed in Chapter 6. Recall that evolutionary psychology includes the idea that selection pressures lead to certain gender differences. These differences stem from the fact that human females have greater investment than males in offspring (through the long period of pregnancy and mothering). For this reason, females are believed to be choosy about mates---trying to find one who will provide resources for her children. A gender difference in dominance and aggression is also believed to follow from the differing selection pressures. In that view, aggression can increase males' opportunities to mate. Aggressiveness helps males establish dominance and status. One study found that when male monkeys in a troupe were threatened by an outside rival, their testosterone went up, facilitating displays of aggression and dominance (Cristóbal-Azkarate, Chavira, Boeck, Rodríguez-Luna, & Veàl, 2006). An extensive review of literature in humans supports that conclusion and others, as well (Archer, 2006). For example, when men are required to care for offspring, testosterone decreases. There are also interesting individual differences in testosterone effects. For example, after being insulted, men from the American South have a greater increase in testosterone than men from the North (Cohen, Nisbett, Bowdle, & Schwarz, 1996). This has been interpreted as indicating a stronger culture of honor in the South, which increases the impact of an insult. Overt aggressiveness in females doesn't confer the same advantage as it does to men and may even be a disadvantage. It can create the potential for damage to an unborn or young child. It also interferes with women's more important activities (bearing and raising children). Nonetheless, testosterone does relate to aggression among women as well as men (Archer, 2006). That this can be a problem for women is suggested by findings that this assertive style interferes with forming alliances in female groups (Archer & Coyne, 2005). Dabbs (1992b, 1998) noted an interesting irony about testosterone effects. In the evolutionary view, males are high in testosterone and dominance because physical domination over other males brought access to mates. In recent millenia, however, the rules have changed, at least a little. Success is now defined partly by socioeconomic status, rather than physical dominance. A man who's too preoccupied with displays and posturing may have trouble gaining the skills needed for economic and social power. Thus, a quality that was important in prehistory may actually interfere with success in today's world. 7.6.6: Responding to Stress Another hormonal influence has drawn considerable attention in recent years. It concerns responses to stress, but goes far beyond. A phrase that's well known in psychology, coined long ago by Cannon (1932), is the fight-or-flight response. It refers to the fact that when an animal confronts a predator or competitor, it has two adaptive choices: to attack (hoping to overcome the other) or to flee (hoping to escape). It's often been assumed that these are the only important responses to threat. Shelley Taylor (2002, 2006) and her colleagues (Taylor et al., 2000) argue that this assumption is wrong. As they point out, most of the evidence for that view comes from studies of males (and mostly male rats, at that). Females were studied in a few stressful contexts, but the behavior examined in those studies wasn't about fight or flight. Rather, the behavior has concerned affiliation---particularly, affiliation with other women. Taylor et al. (2000) argued that focusing on male behavior caused an important set of responses to be widely ignored. They refer to these responses, which are stronger in females than in males, with the phrase tend and befriend. Taylor et al. think the existence of these responses reflects a difference in evolutionary pressures on males and females, due to differing investment in offspring. That is, as just noted, fighting and fleeing may make good sense for males, who aren't carrying offspring (or pregnant), but it makes less sense for females. Females thus may have evolved strategies that benefit both themselves and their offspring. Tending refers to calming offspring. This protects them from harm. That is, if they don't cry, they (and you) fade into the background, where the threat is less. By extension, you do the same for close adults who are stressed. By soothing them, you put them into a situation of less threat. Befriending means affiliating and bonding with others. This reduces certain kinds of risk (because there's greater safety in numbers) and increases the chances of receiving tending from each other when needed (Taylor, 2002). This pattern of response is believed to derive from the system that produces attachment between infant and caregiver. Attachment is often discussed from the perspective of the infant's bond to a caregiver (see Chapter 9). It's less often discussed the other way around. Yet there's a good deal of research on this topic, and aspects of the biological mechanism that creates it have been identified (Panksepp, 1998). This system involves a hormone called oxytocin. It acts to relax and sedate (e.g., Light et al., 2000), to reduce fear, and enhance mother--infant bonding (Feldman, Weller, Zagoory-Sharon, & Levine, 2007). Both males and females have this hormone, but females have more of it. Furthermore, androgens inhibit its release under stress, and estrogen increases its effects (see Taylor et al., 2000). Thus, men and women react somewhat differently to stress. Men tend to remove themselves from social interaction; women immerse themselves in nurturing those around them (Repetti, 1989). The idea that oxytocin is involved in mother--infant bonding is a starting point. But it also seems to be involved in social bonding more generally (Carter, 1998; Panksepp, 1998; Taylor et al., 2000; Turner, Altemus, Enos, Cooper, & McGuinness, 1999). Animal research shows that oxytocin plays a key role in adult pair bonding in some species. It's released during orgasm, childbirth, massage, and breastfeeding (Matthiesen, Ransjö-Arvidson, Nissen, & Uvnäs-Moberg, 2001; Turner et al., 1999). Greater partner support relates to higher levels of oxytocin (Grewen, Girdler, Amico, & Light, 2005). There's also evidence that receiving a jolt of oxytocin causes people to experience an increase in trust, a willingness to take on risks in the context of a social bond with a stranger (Kosfeld, Heinrichs, Zak, Fischbacher, & Fehr, 2005). It improves the ability to empathically infer other people's mental states (Domes, Heinrichs, Michel, Berger, & Herpertz, 2007). But it also increases the tendency to conform to one's in-group rather than an out-group (Stallen, De Dreu, Shalvi, Smidts, & Sanfey, 2012). Interestingly, because some of its effects reflect conformity to cultural norms, it can cause seeking of support in response to stress or emotional suppression of distress, depending on what one's culture considers appropriate (Kim et al., 2010; Kim et al., 2011). And what about personality? One recent study found oxytocin related to lower lifetime aggression (Lee, Ferris, Van de Kar, & Coccaro, 2009). Another study (Creswell et al., in press) found oxytocin genes are related to negative affectivity and social inhibition. With a few exceptions, however, there's not much evidence linking oxytocin to personality traits. Human research on oxytocin is just gaining momentum, partly because it's harder to study than some other hormones. If oxytocin is important in the formation of social bonds, though, it's a key biological influence on human experience. Undoubtedly, its influence on personality will be the subject of work in the years to come. 7.7: Assessment from the Biological Process Perspective 7.7 Describe the processes of electroencephalograms and neuroimaging as biological methods of assessing personality The biological view on personality discussed in this chapter assumes that personality derives from events in the nervous system and hormonal system. If personality is biological, then why not just assess the biological characteristics? There are a couple of problems with this. In many cases, no one's quite sure yet what the biological mechanism is, so it's hard to know what to measure. It's also hard to assess biological functions in a way that doesn't require a sensor in the body or the drawing of blood. Nonetheless, some biological methods of assessment are now in use. 7.7.1: Electroencephalograms An indirect indication of brain activity can be obtained by recording electrical activity from the scalp. The record is called an electroencephalogram (EEG). The reasoning behind the EEG is that neurons in the brain fire at various intervals, creating fluctuations in voltage. Electrodes on the scalp sense these changes, giving a view of aspects of the activity in the cerebral cortex. Cortical activity is very complex, but it forms patterns that relate to different subjective states. EEGs have been used for some time as a way of investigating normal personality. In fact, some of the work discussed earlier in the chapter used EEGs. Various regions of the cortex are active to different degrees when people are in different psychological states. Mapping EEG activities in different locations shows what areas of the brain are involved in what kinds of mental activity. For example, it's possible to identify a person who's dominated by incentive motivation or by avoidance motivation by looking at left- versus right-prefrontal activation levels at rest (Harmon-Jones & Allen, 1997; Sutton & Davidson, 1997). 7.7.2: Neuroimaging Mapping of brain activities has also moved inside the brain. One technique, called positron emission tomography (PET), derives a picture of brain functioning from metabolic activity. The person receives a radioactive form of glucose (the brain's energy source). Then later, radioactivity is recorded in different brain areas. Presumably, more active areas use more glucose, resulting in higher radioactivity there. A computer color-codes the intensities, producing a brain map in which colors represent levels of brain activity. Another technique, called magnetic resonance imaging (MRI), relies on a very subtle property of nerve activity. Nerve cells create magnetic fields. With a good deal of computer assistance, the magnetic resonances of a person's brain can be translated into a visual image. Typically, the image is of slices across the brain, as seen from above. Different slices give different information, because they show different parts of the brain. At first, MRI images were used primarily to look for structural problems in the brain. For example, if you were having blackouts after an auto accident, you might be asked to undergo an MRI to look for possible damage. MRIs are also now being used in a different way. People are being studied to assess levels of activation in various brain regions, both at rest and when engaged in tasks. The picture from this sort of study, called functional MRI (fMRI), is much more detailed than what comes from EEG recordings. Of particular importance is that it lets the brain be viewed in slices at different levels. The result is a very detailed three-dimensional picture about what brain centers are active during the scan. As with PET scans, the images are usually created in multiple colors, with each color representing a different level of activity. Use of fMRI has increased at an incredible rate over the past two decades. It's very expensive (because it requires a giant, powerful magnet, plus a lot of skilled technical support). But the fact that it can provide a three-dimensional picture means it can show precise locations of increases and decreases in neural activity as a function of what the person is doing. People can be placed in different motivational and emotional states while in the device and can engage in diverse tasks. This lets researchers determine which parts of the brain are involved in those various experiences. This kind of work is greatly expanding knowledge of how the brain is organized and what functions it is serving. More and more researchers are thinking of possible uses for neuroimaging tools. This is a research area that unquestionably will continue to grow enormously in the years to come. 7.8: Problems in Behavior, and Behavior Change, from the Biological Process Perspective 7.8 Analyze how anxiety problems and antisocial behavior may be based in biology Let's now turn to problems in behavior. The biological process approach has made large contributions to the understanding of disorders. We focus here on contributions that relate to the ideas discussed earlier in the chapter. 7.8.1: Biological Bases of Anxiety and Depression Recall that a basic assumption of these models is that separate motivational systems in the brain manage the approach of incentives and avoidance of threats, respectively. People presumably vary in the strength or sensitivity of these systems. Being too extreme on one or the other system may set a person up for problems. Perhaps the easiest problem to link to this view is anxiety disorders. The avoidance system creates fear or anxiety in the presence of cues of impending punishment. A person with a very sensitive threat system will experience these emotions easily and frequently (Blackford, Avery, Cowan, Shelton, & Zald, 2010; Haas, Omura, Constable, & Canli, 2007). This creates fertile ground for an anxiety disorder to develop. If these people are exposed to frequent punishment during childhood, they learn anxiety responses to many stimuli. The result may be the development of such clinical symptoms as phobias, panic attacks, and obsessive--compulsive disorders. A related problem is depression. There's less consensus on the biological roots of depression than on those of anxiety (Davidson, Pizzagalli, Nitschke, & Putnam, 2002). Some researchers see depression as a variant of anxiety, reflecting an oversensitive avoidance system. Others tie depression to a weak BAS (e.g., Allen, Iacono, Depue, & Arbisi, 1993; Henriques & Davidson, 1990, 1991). In this view, a person with weak BAS activation has little motivation to approach incentives. The result is the lifeless, weary behavioral qualities that typify depression. Both problems---anxiety and depression---are likely to be worse if the person also has deficits in the third system: the one that corresponds to constraint or effortful control (Carver et al., 2008). When that system isn't operating effectively, emotions feel more intense and demanding, and it's harder for the person to escape from them (Spoont, 1992). Indeed, the argument is now being made by some that hyper-responsiveness to emotions characterizes a wide variety of disorders (Johnson, Carver, & Joormann, 2013; Johnson-Laird, Mancini, & Gangemi, 2006). 7.8.2: Biological Bases of Antisocial Personality Another problem that's often discussed in terms of biological systems is antisocial personality. As noted earlier, this problem involves impulsivity and an inability to restrain antisocial urges. It's often argued that people with this personality have an overactive BAS (Arnett et al., 1997; Joseph et al., 2009). Thus, they pursue whatever incentive comes to mind. It's also sometimes argued that they have deficits in the threat system (Fowles, 1980). Thus, they fail to learn from punishment or aren't motivated to avoid it. Some think the failure to learn from punishment stems not from a deficient avoidance system but from a failure to stop and think before plowing ahead in pursuit of an incentive (Bernstein, Newman, Wallace, & Luh, 2000; Patterson & Newman, 1993; Schmitt, Brinkley, & Newman, 1999). This would tend to link antisocial personality to the system that underlies impulsiveness and sensation seeking (Krueger et al., 1994; Rowe, 2001; Zuckerman, 1994). This would also represent yet another case in which the problem appears to reflect an over-responsiveness to emotions (Johnson et al., 2013; Johnson-Laird et al., 2006) but a different set of emotions. Insufficient MAO (associated with this system) may also be a vulnerability, interacting with an adverse environment (Raine, 2008). In one study (Caspi et al., 2002), boys with alleles causing low MAO engaged in more antisocial behavior---but only if they also were maltreated while growing up (see Figure 7.5). Although men with the combination of low MAO allele and severe maltreatment were only 12% of the male birth cohort, they accounted for 44% of the cohort's violent convictions. Indeed, a full 85% of this group developed some sort of antisocial behavior. Figure 7.5 Scores on an index of antisocial behavior among men with a gene causing low MAO and men with a gene for normal MAO who had experienced either no maltreatment (abuse) during childhood, probably some maltreatment, or severe maltreatment.  Figure 7.5 Full Alternative Text Some discussions of antisocial behavior involve other biological systems, as well. Recall that high levels of testosterone relate to various kinds of violent and antisocial behavior (Dabbs & Dabbs, 2000; Dabbs et al., 2001). There's even evidence that high testosterone relates to disruptive behavior in boys as young as 5 to 11 years of age (Chance, Brown, Dabbs, & Casey, 2000). Thus, this set of problems seems to relate to both hormonal and neural processes. 7.8.3: Biological Therapies The biological process approach to personality also has relatively straightforward implications regarding therapy. Many manifestations of problems reflect biological functions. It follows that changing the action of these biological functions should change the manifestation of the disorder. There are several disorders for which this approach seems effective. The treatments typically involve administering drugs. Those treatments are often called pharmacotherapy. It has long been known that bipolar, or manic--depressive, disorder can be relieved by taking lithium. About 80% of people with bipolar disorder respond to lithium (Depue, 1979). Besides treating existing symptoms, repeated doses can ward off new symptoms. Unfortunately, lithium has serious unpleasant side effects. Nevertheless, its effectiveness supports two ideas: that the disorder is biological and that its treatment should be (at least in part) biologically based. A similar case can also be made for the treatment of schizophrenia. One long-standing hypothesis is that the symptoms of schizophrenia reflect too much dopamine (Grace, 2010; Walker & Diforio, 1997). With too much dopamine, transmission in certain parts of the nervous system is too easy. When too many messages are being sent at once, communication is disrupted. This hypothesis is supported by some studies of biochemical treatments for schizophrenic symptoms. As it turns out, drugs that remove the symptoms of schizophrenia also lower the levels of usable dopamine in the brain. Apparently, the effectiveness of these drugs is related to their ability to block dopamine use. Once again, this finding suggests that the disorder is biological and that the treatment should also be biologically based (at least in part). Drug treatments are also used for disorders that are far less extreme than the two just discussed. Antianxiety drugs are among the most often prescribed of all medications. Many people with moderate to mild depression take antidepressants, one group of which is called selective serotonin reuptake inhibitors (SSRIs). Indeed, development of this set of antidepressants has led to a far wider use of mood-altering medication than ever before. The widespread use of these drugs raises a number of questions and issues (Kramer, 1993). One issue concerns the fact that responses to the medications often are much broader than the mere lifting of a depressed mood. People's personalities undergo changes that are subtle but profound and pervasive. People become more confident, more resilient, more decisive---almost more dominant---than they were before. In a sense, they aren't quite the same people as they were before taking the medication. Their very personalities have changed. Seeing these changes in personality as a function of a slight alteration in brain chemistry raises questions about where personality resides. Personality may consist of the person's biological functioning and the experiences to which it gives rise. Personality may not be a stable entity that stands apart from the symptoms that bring people for therapy. Personality, in the form of the person's biological systems, may be the source of the symptoms. Researchers have gone on to ask whether SSRIs affect people who don't have a disorder. One study (Knutson et al., 1998) gave people either an SSRI or a placebo for four weeks and assessed them before and afterward. Those given the medication reported less hostility and negativity afterward (but not greater positive feelings). They also displayed more positive social behavior while working on a cooperative task. Another study (Tse & Bond, 2001) found an increase on a measure of self-direction, which assesses such qualities as purposefulness and resourcefulness. The availability of drugs with these broad effects on personality raises more questions: How widely should they be prescribed? Should people whose problems aren't severe be given medication if it will make their lives more enjoyable? Should all people have the option of changing their personalities by taking pills? Researchers are a long way from answering these questions. Another biologically based treatment possibility has begun to emerge in recent years, called transcranial magnetic stimulation, or TMS (Holtzheimer & McDonald, 2014). TMS involves focusing a magnetic field on a specific location in the brain. Because of the magnetic properties of active neurons (discussed earlier), applying this stimulation has the effect of either reducing activity in the area it's aimed at (if the pulses are low frequency) or increasing it (if the pulses are high frequency (Sauvé & Crowther, 2014). In its early use, TMS was applied mostly to cases of depression that had not responded to other treatments, even biologically based treatments such as electroconvulsive therapy (ECT). Evidence has steadily accumulated that it can be effective for such cases (Janicak & Carpenter, 2014). TMS treatment has been used to increase activity in left frontal brain areas, identified in research described earlier in the chapter as being involved in approach behavior. Treatment to reduce activity has been used in right frontal areas, identified as involved with avoidance behavior. If the treatments fostered greater and lesser activity, respectively, in those areas, the result would be improvements in pursuit of rewarding activities and reductions in anxiety. These would be the perfect changes for a person who is depressed. Clinical problems such as depression are not the only things that might benefit from TMS. Research has also begun to find that TMS can be used to enhance mental processes in people who don't have problems (Luber & Lisanby, 2014). TMS is a very young technology, but interest in it and enthusiasm for it have increased over the past few years. People are working hard to improve the devices that deliver the magnetic pulses, so that they can be better controlled and more narrowly aimed. Many believe that TMS will eventually be a key tool in the treatment of a wide range of problems. 7.9: Problems and Prospects for the Biological Process Perspective 7.9 Identify how progress in the biological process approach to personality depends on advances in other fields This chapter has discussed the idea that patterns of biological processes have important things to tell us about personality. We wouldn't blame you if you came away feeling that the presentation was a little fragmented. In truth, the ideas themselves are somewhat fragmented. The pieces are coming together, but they're not there yet. As a result, this way of thinking about personality has something of a disjointed feel. One reason for this is that theories about how the nervous system and hormones influence behavior rely, in part, on knowledge from other sciences. Ideas in those sciences are continually evolving, causing changes in the ideas about personality. Furthermore, work on these topics is as new as the methodological advances that permit a closer look at how the biological systems function. These methodological advances continue to march forward (Davidson et al., 2000; Lane & Nadel, 2000; Posner & DiGirolamo, 2000). The result is a kaleidoscope of new looks at biological functioning that sometimes have unexpected implications for personality. For example, many psychologists now have access to PET scans and fMRIs, which illuminate brain functioning in ways only dreamed of a few years ago. However, the findings generated from these techniques have raised as many new questions as they have answered. Sorting out the picture that such methods reveal will likely be a complex process. It's clear that there's been progress in these areas of research and thought. To a large extent, theorists agree about what they're trying to account for. There's a general consensus that approach and avoidance (and positive and negative feelings) are important focal points for biological theory building, along with the fact that we seem to have some basis for sorting out what to focus on and what to set aside. Almost everyone seems to feel the need to include something more than that, but there's been less of a consensus about what else to include. Partly for this reason, this way of thinking doesn't yet stand as a fully developed personality theory. It's more of a vantage point---a place from which to look at and consider the nature of personality. Lest you be tempted to conclude from the disagreements that these theorists aren't doing their homework carefully enough, let us point out that it's hard to tell what's going on in the nervous system. To really know what connects to what in the brain means tracing neural pathways, which can't be done in human subjects. When animal research is done, the animals can't report directly on the psychological effects of what the researcher is doing. Thus, information often is indirect, and progress can be slow. The functions of the nervous system are being sorted out by research of several types, but there's a long way to go. Until the nature of the organization of the nervous system becomes clearer, personality psychologists of this orientation are unlikely to have definitive models. Although criticisms can be made of various aspects of this way of thinking about personality, this line of work is one of the most active areas of personality psychology today. Many people believe that the mysteries of the mind will be revealed by a better understanding of the brain. They are committed to unraveling those mysteries and their implications for personality. The prospects of this viewpoint seem quite bright indeed. Summary: Biological Processes and Personality The idea that personality is tied to the biological functions of the body leads to a variety of possibilities involving the nervous system and the hormone system. An initial approach of this sort was Eysenck's theory that brain processes underlie extraversion and neuroticism. He argued that introverts are more aroused cortically than extraverts and that people high in neuroticism are more aroused emotionally than those low in neuroticism. Others have taken a different path, relying on newer knowledge. It's now often argued that personality rests on an approach system (BAS) that responds to incentives and an avoidance system that responds to threats. Work on emotions suggests that the approach system involves (in part) the left prefrontal cortex and that the withdrawal system involves (in part) the right prefrontal cortex. The threat system seems to -represent the biological basis for the trait of neuroticism. Some researchers suggest that the BAS represents the biological basis for extraversion. Many people now believe it's useful to assume that another biological system is responsible for variations in impulsiveness and sensation seeking (the tendency to seek out novel, complex, and exciting stimuli). Sensation seeking relates to Eysenck's psychoticism dimension and Tellegen's constraint dimension, and both relate to the temperament of effortful control. Variation in these qualities may be grounded in differences in the functions that cause people to take into account other people and long-term goals. Another aspect of the biological view on personality focuses on the influences of hormones on behavior. Exposure to male hormones before birth can cause people years later to choose more aggressive responses to conflict and can increase girls' preference for boys' toys. Testosterone in adults relates to dominance behavior, sometimes expressed in antisocial ways. Testosterone also fluctuates with the context, increasing with challenges and victories and decreasing with failures. An emerging area of work examines the possibility that another hormone, called oxytocin, is important in human social behavior. Oxytocin appears to relate to female responses to stress, termed a tend-and-befriend response. The roots of this response may be in the attachment system, and it may relate to social bonding more generally. The biological process approach to personality suggests that it may be possible to assess personality through biological functions. Although the attempt to do this is in its infancy, some researchers believe recordings of brain activity---particularly fMRIs---hold great promise for the future. With regard to problems in behavior, high levels of threat sensitivity promote disorders involving anxiety. Either a high threat response or a low approach response may contribute to depression. High approach--low avoidance can yield symptoms of antisocial personality, which also relates to impulsive sensation seeking and testosterone. This orientation to personality suggests that therapy based, in part, on medication is a means to bring about behavioral change. The idea is that medication can influence the underlying biological system, thereby altering the person's behavior and subjective experience.