Brain Electrical Activity and Cerebral Asymmetry PDF

Assessment: Brain Electrical Activity and Cerebral Asymmetry 221 Ekman, Saron, Senulis, & Friesen, 1990). When participants experienced happiness, as determined by their facial expressions, the activity in their left cerebral hemisphere increased. When participants experienced disgust, there was m...

Assessment: Brain Electrical Activity and Cerebral Asymmetry 221 Ekman, Saron, Senulis, & Friesen, 1990). When participants experienced happiness, as determined by their facial expressions, the activity in their left cerebral hemisphere increased. When participants experienced disgust, there was more activity in the right hemisphere. Similar patterns were found in children less than a year old. In one study with 10-month-old infants, smiling was associated with higher left hemisphere activity, whereas crying was associated with higher right hemisphere activity (Fox & Davidson, 1988). In other experiments, infants showed increases in left hemisphere activity when their mothers reached down to pick them up (Fox & Davidson, 1987), when they heard laughter (Davidson & Fox, 1982), and when they tasted something sweet (Fox & Davidson, 1986). In all cases, the children experiencing positive emotions had more activity in their left hemisphere than in the right. Because the infants had not yet reached their first birthday, researchers argued that the association between cerebral asymmetry and emotion is something we are born with rather than the result of learning. Individual Differences in Cerebral Asymmetry Additional research has taken the association between cerebral asymmetry and emotion one step further. Most people typically have higher activation in one hemisphere than in the other, even when in a relatively nonemotional resting state. However, which hemisphere displays the higher activity level is not the same for everyone. Some people tend to have higher activity in the left hemisphere when resting, whereas others tend to have more right hemisphere activity. Like other individual differences, differences in cerebral asymmetry tend to be fairly stable over time. If you show a higher level of activity in one hemisphere over the other today, you will very likely show the same pattern when taking an EEG test next week or even next year. Moreover, these differences in cerebral asymmetry show up early in life. They are found in infants less than a year old and remain consistent throughout childhood (Howarth, Fettig, Curby, & Bell, 2016; Muller, Kuhn-Popp, Meinhardt, Sodian, & Paulus, 2015). These findings suggest that children are born with these proclivities, although it is also possible that experiences like stress and maltreatment could have an effect in some cases (Peltola et al., 2014). These findings have led to another intriguing question. Because left and right hemispheric activity is associated with positive and negative moods, can we use differences in cerebral asymmetry to predict differences in emotion? The answer appears to be “Yes.” Participants in one study were identified as having either higher left hemisphere or higher right hemisphere activity when resting (Davidson & Tomarken, 1989). These individuals then watched films designed to elicit certain emotions, such as happiness or fear. As predicted, people with a higher level of left hemisphere activity were more responsive to the positive mood films whereas participants with higher right hemisphere activity levels reacted more to the films that produced negative moods. Again, similar patterns can be found in infants (Gartstein, Bell, & Calkins, 2014; Smith, Diaz, Day, & Bell, 2016). Ten-month-old babies in one study were identified as having either higher left hemisphere or higher right hemisphere activity when resting Copyright 2019 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 222 Chapter 9 / The Biological Approach (Davidson & Fox, 1989). The babies were then divided into those who cried and those who did not cry when separated from their mothers. As expected, the criers tended to have higher right hemisphere activity, whereas the noncriers had higher left hemisphere activity. Another study found that infants with higher left hemisphere activity were more likely than children with higher right hemisphere activity to interact with their mothers in a playful and relaxed way (Licata, Paulus, Kuhn-Popp, Meinhardt, & Sodian, 2015). How can we account for these findings? Initially researchers explained the results in terms of thresholds for positive and negative mood (Davidson & Tomarken, 1989). They speculated that people with higher right hemisphere activity require a less intense negative event to experience fear or sadness. A minor disappointment or a rude remark might be enough to push them over the threshold into a negative emotional state. On the other hand, people who generally have a higher level of left hemisphere activity may require a less intense positive event before they experience happiness. An enjoyable conversation or a favorite song on the radio might be enough to trigger pleasant emotions. However, subsequent research findings have caused psychologists to recast the relationship between cerebral asymmetry and emotions. Instead of looking at positive and negative emotions, psychologists now describe the differences in terms of approach and withdrawal tendencies (Pizzagalli, Sherwood, Henriques, & Davidson, 2005; ­Rutherford & Lindell, 2011). Studies find that left hemisphere activity is related to movement toward the source of the emotion whereas right hemisphere activity is related to movement away. Thus, higher right hemisphere activity is associated with sadness because depression is essentially an effort to withdraw from whatever is causing the emotion. Higher left hemisphere activity is associated with joy because happiness draws us toward the source of the emotion. Consistent with this analysis, researchers find that anger is related to higher left hemisphere activity (­Chavanon, Leue, & Stemmler, 2008; Harmon-Jones, Lueck, Fearn, & Harmon-Jones, 2006; ­Kelley, Hortensius, & Harmon-Jones, 2013). Although anger is a negative emotion like depression, angry people tend to approach or even attack the source of their distress. The demonstrated association between cerebral asymmetry and emotion has led researchers to yet another question: Do differences in hemispheric activity level play a role in the development of emotional disorders? Some research findings suggest that they may. Depressed participants in these studies show more right-side activation than nondepressed participants (Jesulola, Sharpley, Bitsika, Agnew, & Wilson, 2015; Nelson et al., 2012; Stewart, Bismark, Towers, Coan, & Allen, 2010; Thibodeau, Jorgensen, & Kim, 2006). Other investigations find anxiety sufferers also have higher right-side activation than nonanxious individuals (Crost, Pauls, & Wacker, 2008; Mathersul, Williams, Hopkinson, & Kemp, 2008; Thibodeau et al., 2006). In one investigation, researchers examined EEG patterns in people who were currently not depressed but who had suffered from previous bouts of depression (Henriques & Davidson, 1990). These individuals tended to have less left hemisphere activity than a group of participants who had never suffered from depression. In other words, these previously depressed individuals may have a physiologically based vulnerability to bouts of depression. Finally, if cerebral asymmetry is a marker for vulnerability to emotional disorders, can we use EEG patterns to predict who is likely to suffer from these disorders in the future? Once again, the answer appears to be “Yes.” One team of researchers Copyright 2019 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Strengths and Criticisms of the Biological Approach 223 measured cerebral asymmetry in a group of college students who had no history of emotional problems (Nusslock et al., 2011). The students were then interviewed every 4 months for the next 3 years to determine whether the student had experienced a significant episode of depression. As expected, students with higher right-side activation were more likely to experience their first depressive episode during this time than those with higher left-side activation. Measures of cerebral asymmetry have also been used to predict whether people who suffer from mood swings will develop bipolar disorder (Nusslock, et al., 2012). Clearly, whether we experience any emotional disorder depends on many factors, including the kinds of situations we encounter. But it may be that some people are biologically wired to require fewer or less intense negative experiences than others before succumbing to feelings of depression or anxiety. Strengths and Criticisms of the Biological Approach Strengths One of the strengths of the biological approach is that it provides a bridge between the study of personality and the discipline of biology. For too many years, personality psychologists often ignored the biological roots of human behavior. But it has become increasingly difficult to disregard the fact that we are the product of an evolutionary history and our individual genetic makeup. Human behavior is influenced by many factors, one of which is biology. By incorporating what biologists know about evolution and genetics, personality psychologists come closer to understanding what makes each of us the kind of person we are. The biological approach also has succeeded in identifying some realistic parameters for psychologists interested in behavior change. The “blank slate” image of humankind can be very appealing. If the newborn personality is like clay, then with enough knowledge, resources, and effort we should be able to mold that personality any way we want. If all babies are essentially alike, then with enough research psychologists could advise parents and teachers on the “correct” way to raise all children and teach all students. Unfortunately, past acceptance of the blank slate notion created many problems. Parents with difficult-to-control babies were blamed for not knowing how to raise their children. Highly active children were punished for not sitting still. Advocates of the biological approach argue that our inherited biological differences probably place limits on the kind of children and adults we can become. Another strength of the biological approach is that most of its advocates are academic psychologists with a strong interest in testing their ideas through research. Consequently, investigators have generated empirical support for many of the hypotheses advanced from this perspective. In addition, psychologists from the biological approach have often modified their theories as a result of research findings. For example, after Eysenck outlined a comprehensive model of personality several decades ago, he and others conducted research on many of the predictions generated from the model. Much of this work supported Eysenck’s ideas, but investigators altered other ideas to better reflect the research findings. Copyright 2019 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 224 Chapter 9 / The Biological Approach Criticisms Despite their focus on research, advocates of the biological approach sometimes face limits on their ability to test their ideas. In particular, evolutionary personality psychologists often are left to argue from the relatively weak position of analogy and deduction (Eagly, 1997). A reasonable case can be made that anxiety helps the species survive because it prevents social isolation. But how can we test this hypothesis? Direct manipulation is often out of the question, making demonstrations of cause-and-effect relationships difficult, if not impossible. One problem with this limitation is that we can think of a potentially adaptive function for nearly every human attribute. For example, some psychologists have argued that depression is adaptive because it leads us to give up on unattainable goals and thereby save resources (Wrosch & Miller, 2009). There is some logic to this analysis, but it is quite a leap to say that we were better able to survive as a species because we have the capacity to become depressed. To fully appreciate why this ability to explain everything is a problem, consider the example offered by one psychologist (Cornell, 1997). As discussed in Chapter 10, some researchers use evolutionary theory to explain gender differences, such as why men are more dominant, stronger, and more sexually promiscuous than women (Archer, 1996; Gangestad & Thornhill, 1997). But imagine if just the opposite were the case—that men were more timid and physically weaker than women and less likely to seek out multiple sex partners. One could use evolutionary theory to explain these results as well. We could speculate that because men were free to roam and did not have to protect offspring, the tendency for them to timidly run away from potential fights evolved. Women evolved to be stronger because childcare responsibilities required them to carry children, lift them into trees for safety, and fight off predators. And sexual promiscuity allowed a woman to avoid the risk of pairing up with a man who might be unable to make her pregnant and thus not allow her to pass along her genes. As this example illustrates, if a theory can explain all possible outcomes, it cannot be tested. Other critics of evolutionary personality theory challenge the assumption that every human characteristic must serve a survival function. It is entirely possible that a characteristic evolved that had no impact on survival or that even hurt our species’ likelihood of survival. For example, a critic might ask what the survival value could possibly be for the tendency for men to grow hair in their ears as they age or for urine to smell funny after eating asparagus. Of course, with a little creativity, we can probably come up with an answer. But that exercise would only reinforce the problem of being able to explain everything. Another criticism of the biological approach is directed at theory and research on temperament. Students and researchers may be bewildered by the lack of an agreedupon model. One prominent model identifies three basic temperaments. Yet other models describe five, seven, and nine temperament dimensions (Bates, Wachs, & Emde, 1994). Students have the right to ask which of these models is correct. More important, it is difficult to make comparisons across investigations when researchers rely on different names and descriptions for these temperaments. Is the “inhibited” child the same as the “slow-to-warm-up” child? We can hope that clearer answers about the number and description of basic temperaments will be forthcoming as researchers continue to work in this area. Copyright 2019 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Summary 225 Finally, like the trait approach, the biological approach offers few suggestions for personality change. Although many ideas from this approach are probably useful for psychotherapists, there are no schools of psychotherapy based on this perspective. On the contrary, the message from the biological approach is that we need to be more aware of some of the limitations on how much we can change people. On the other hand, therapists might do well to recognize that, because of biological differences, not all clients respond the same to their treatments. Summary 1. Hans Eysenck was an early proponent of the biological approach to personality. He argued that personality can be divided along three primary dimensions. He called these extraversion–introversion, neuroticism, and psychoticism. Eysenck argued that differences in personality are largely based in inherited biological differences. Research suggests that introverts are more sensitive to stimulation than extraverts and that extraverts may be more attracted to rewards. 2. Personality researchers have identified general inherited dispositions called temperaments. Psychologists argue that temperaments are largely inherited and that these inherited dispositions interact with experiences to form adult personality traits. Children identified as inhibited show a fear of unfamiliar situations that other children do not. There is evidence that this tendency remains fairly stable throughout childhood and may contribute to problems like social anxiety. 3. Evolutionary personality psychology uses the concept of natural selection to explain the development and survival function of human personality characteristics. Theorists point out that anxiety often results from events related to social rejection. They argue that because social isolation decreases the chances of survival and reproducing, the evolution of anxiety has helped the species survive. 4. Research on temperament has important implications for education. Studies find that children identified with a difficult temperament pattern and those identified with a slow-to-warm-up pattern perform more poorly in school than children identified with an easy temperament pattern. Research suggests that children learn best when the demands of the learning environment match the child’s temperament. 5. Personality researchers often use physiological measures in their research. Some researchers use EEG data to look at individual differences in emotions. They find that differences in the activity levels of the right and left halves of the cerebral hemispheres are associated with differences in mood. Some research indicates that people inherit different base-rate levels of brain activity in the two hemispheres and that this difference may make them more likely to experience certain emotional experiences. Copyright 2019 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 226 Chapter 9 / The Biological Approach 6. One strength of the biological approach is that it ties personality psychology to the discipline of biology. In addition, research in this area has identified realistic limitations for the blank slate model of personality development. Another strength of the biological approach is its strong emphasis on research. Criticisms of the approach include the difficulty researchers have when testing some of their ideas. Other criticisms are that researchers have not agreed upon a single model for temperament and that the biological approach provides little information about behavior change. Key Terms behavioral approach system (BAS) (p. 205) cerebral asymmetry (p. 220) uninhibited children (p. 211) inhibited children (p. 210) temperaments (p. 208) behavioral inhibition system (BIS) (p. 205) Copyright 2019 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.