Chapter 10: The Biological Approach PDF
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Santa Clara University
Jerry Burger
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This chapter examines the biological approach to understanding extraversion and introversion, exploring how individual preferences for stimulation levels might be rooted in genetic predispositions. It also explores how extraverts and introverts might respond differently to various levels of stimulation, both in social and solitary contexts.
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Chapter 10 / The Biological Approach Jerry Burger/Santa Clara University 238 Is this student an introvert or an extravert? According to research, his choice of study area provides a clue. Extraverts prefer this type of open study area where opportunities for interruptions and occasional social st...
Chapter 10 / The Biological Approach Jerry Burger/Santa Clara University 238 Is this student an introvert or an extravert? According to research, his choice of study area provides a clue. Extraverts prefer this type of open study area where opportunities for interruptions and occasional social stimulation are possible. None of this means that you can’t be more outgoing at times if you are highly introverted or learn to stop and introspect for a few minutes if you’re an extravert. It also does not mean that environmental influences aren’t a factor. But we can say that most likely where you fall on the extraversion–introversion continuum was largely determined by the genetic hand you were dealt many years ago. Extraversion and Preferred Arousal Level Imagine it’s a few days before a big test in one of your classes. You’ve put off preparing for the exam long enough, so tonight you’ll go to the library and spend a few hours behind the books. Imagine also that there are two study areas in this library. One contains a series of one-person desks where you can isolate yourself behind stacks of books. Few people walk by these desks, and the room is relatively free of whispers, photocopy machines, and other sources of noise. The other study area consists of long tables, sofas, and easy chairs. You can easily scan the room to see who else is there. Many people walk by on their way to other parts of the library, and short conversations with those passing through are common. Which of these study areas will you choose? Your choice in this situation depends in part on whether you are an extravert or an introvert. One team of researchers demonstrated this phenomenon when they asked students studying in the two kinds of library sections just described to complete an 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. Extraversion – Introversion 239 extraversion inventory (Campbell, 1983; Campbell & Hawley, 1982). Students in the noisy, open area were more likely to be extraverts, whereas the ones in the isolated, quiet places were more likely to be introverts. Those in the noisy section said they preferred the amount of noise and the opportunities for socializing. The others said they chose the quiet area to get away from these distractions. These findings are entirely consistent with the descriptions of extraversion– introversion presented in the previous chapter. Introverted students are more sensitive to stimulation. Thus an introvert in a noisy room is probably so disturbed by all the activity that he or she will have a difficult time studying. On the other hand, the understimulated extravert probably finds the quiet room boring. Unless the study material is particularly exciting, the extravert will probably take a number of breaks, look around for distractors, and generally have a difficult time keeping his or her mind on the task. This difference in preferred stimulation level also is found in more controlled laboratory experiments (Geen, 1983). For example, extraverts more quickly press a button to change slides on a visual learning task, presumably because they become bored more quickly with the pictures and designs (Brebner & Cooper, 1978). One team of researchers found that extraverts, but not introverts, showed a sudden drop in their ability to perform a listening exercise when the task was made less challenging by slowing down the pace (Cox-Fuenzalida, Angie, Holloway, & Sohl, 2006). In another study, extraverts and introverts worked on a word-memory task while listening to noise through earphones (Geen, 1984). When given the opportunity, introverted participants set their earphones at considerably lower levels than did extraverts. However, some introverts in this study were forced to listen to loud noise and some extraverts were restricted to soft noise. As expected, the introverts did worse when exposed to higher levels of stimulation, whereas the extraverts performed worse when listening to the softer noise. Even a pleasant distractor like music can soon become too much for introverts trying to concentrate on a difficult task (Dobbs, Furnham, & McClelland, 2011). These findings help to explain why some students can study only with music playing in their ears or a nearby TV blaring, whereas other students have to find a quiet room and then stuff pieces of foam into their ears to block out any remaining noise. Too much stimulation makes it difficult to concentrate, and even extraverts can reach a point when they have to turn their music down. But for introverts this point comes much earlier. Of course, the other side of the coin is that too little stimulation also interferes with performance. Whereas it may take hours of solitude to bring an introvert to this point, a few minutes in quiet isolation might be tough on a high extravert. Extraversion and Happiness Clearly, extraverts and introverts lead different lives. We are more apt to find extraverts at parties, visiting friends, going places, and generally being active. Introverts are more likely to spend time alone, engaging in quiet, low-stimulation tasks. Who do you suppose is happier? Not surprisingly, I usually find introverts guess introverts are happier people, whereas extraverts can’t imagine how anyone could lead a life as boring as the introverted style. 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. 240 Chapter 10 / The Biological Approach Although introverts may have difficulty understanding this at first, researchers find that on average extraverts report higher levels of happiness than introverts (DeNeve, 1999; DeNeve & Cooper, 1998; Lucas & Baird, 2004; Lucas, Le, & Dyrenforth, 2008; Smillie, DeYoung, & Hall, 2015). Extraverts and introverts in one investigation were asked to provide a daily mood report for 84 consecutive days (Larsen & Kasimatis, 1990). As shown in Figure 10.2, the researchers found an interesting pattern when they compared moods on days of the week. Predictably, Monday was the students’ least favorite day, with the week becoming progressively better as Saturday approached. But the figure also illustrates that no matter what the day of the week, extraverts reported higher levels of positive mood than introverts. One investigation found extraversion scores could predict the number of pleasant experiences people would have over the next four years (Magnus, Diener, Fujita, & Pavot, 1993). However, as is often the case, the relationship between extraversion and happiness also varies from culture to culture. Although extraversion always predicts happiness, the correlation is slightly higher for cultures in which acting extraverted is consistent with the cultural norm (Fulmer et al., 2010). High levels of extraversion also are related to high levels of overall psychological well-being (Kokko, Tolvanen, & Pulkkinen, 2013). One team of researchers measured participants’ extraversion at age 16 and again at age 26 (Gale, Booth, Mottus, Kuh, & Deary, 2013). Higher extraversion scores on these measures predicted higher levels of well-being and life satisfaction when these same participants were contacted decades later when they were in their early 60s. Finally, one investigation found that the higher the average extraversion score in a country, the higher the average citizens’ sense of well-being (Steel & Ones, 2002). 3.0 Positive Mood Scores 2.5 2.0 1.5 1.0 0.5 Mon. Tues. Wed. Thurs. Fri. Sat. Extraverts Introverts Figure 10.2 Sun. Happiness Ratings of Extraverts and Introverts Source: Adapted from Larsen and Kasimatis (1990). 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. Extraversion – Introversion 241 Clearly, extraverts generally experience more happiness than introverts. But why might this be the case? Researchers have uncovered at least two reasons. First, extraverts tend to socialize more than introverts (Srivastava, Angelo, & Vallereux, 2008). Extraverts have more friends, and they interact with those friends more often. Researchers have repeatedly found that social contact is closely tied to feelings of well-being (Diener, 1984). Interacting with friends is usually pleasant, as are other extraverted behaviors, such as going to dances, parties, and football games. Many basic needs, such as feeling socially competent and worthwhile, are also satisfied in these settings (Smillie, Wilt, Kabbani, Garratt, & Revelle, 2015). Introverts as well as extraverts find social contact pleasant. Introverts in one study found themselves in a better mood when instructed by the experimenter to act more extraverted in a group setting (Zelenski, Santoro, & Whelan, 2012). In addition, friends often serve as a buffer against stress. That is, people usually cope with their problems better with their friends’ help than when they try to handle the situation alone. Consistent with this observation, one study found that extraverts were more likely than introverts to seek out friends when they had a problem (Amirkhan, Risinger, & Swickert, 1995). The second explanation for extraverts’ happiness is that, as explained in the previous chapter, they may be more sensitive to rewards or may simply enjoy the pursuit of rewards more than introverts do (Oerlemans & Bakker, 2014; Rusting & Larsen, 1998; Smillie, Cooper, Wilt, & Revelle, 2012). An extravert who receives a good grade on an exam may be more pleased than an introvert receiving the same news. In a laboratory test of this hypothesis, extraverts and introverts were given a test of “Syncretic Skill,” supposedly a new type of intelligence (Larsen & Ketelaar, 1989). Although the test was bogus, participants received information indicating either that they had done well on the test or that they had done poorly. Mood measures indicated that extraverts were much happier than introverts after receiving the positive feedback. Interestingly, extraverts were no more disappointed than introverts when told they had done poorly. Other studies find extraverts are more likely than introverts to seek out tasks they think will make them happy (Tamir, 2009) and that extraverts find rewards in situations that introverts don’t see (Noguchi, Gohm, & Dalsky, 2006). Participants in one investigation simply wrote down words as if taking a spelling test (Rusting, 1999). However, many of the words were homophones (words that sound like other words). Thus in some cases, it was possible to hear a happy word (peace instead of piece) and in other cases to hear a sad word (mourning instead of morning). Although either answer was correct, extraverted participants were more likely than introverts to hear the happy words. Does this mean extraverts are always happier than introverts? Not necessarily. Higher sensitivity to rewards can sometimes lead to problem behaviors. For example, extraversion has been linked to problems with alcohol (Fairbairn et al., 2015; Grekin, Sher, & Wood, 2006; Hill, Shen, Lowers, & Locke, 2000). Extraverts also are more impulsive than introverts. Extraverts are more likely to act on the spur of the moment, and this impulsivity can create problems (Emmons & Diener, 1986). Saying the first thing that comes to mind often is not a good idea. Doing what feels good at the moment without considering the eventual consequences is also fraught with danger. Anyone who has enjoyed a trip to the beach or an evening with friends instead of writing a term paper can appreciate the problem of acting impulsively. Thus extraversion 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. 242 Chapter 10 / The Biological Approach appears to be a two-edged sword. Extraverts are more likely than introverts to have friends and have fun, but they also are more likely to act before thinking and get themselves into trouble. Introverts may not always reap the benefits of social interactions, but they avoid the price of lapses in judgment. Evolutionary Personality Theory and Mate Selection I magine that, like many people these days, you decide to look for a romantic partner through an online dating service. As you move through the process of entering information about yourself, you find that you are faced with two challenging tasks. First, you must describe yourself in a way that will make you attractive to others. Second, you must identify the kind of person you are looking for. What do you say? Once they get past favorite songs, dream evenings, and references to piña coladas, researchers find that how people describe themselves and the kind of person they are looking for in these situations depends largely on whether they are male or female (Harrison & Saeed, 1977; Kelley & Malouf, 2013). Women tend to identify themselves as physically attractive and say they are looking for someone who is older and can provide financial security. Fortunately, these requests fit rather well with what the men say. Men typically are looking for someone who is younger and physically attractive. They also are likely to describe themselves as someone who can provide financial security. In addition to their practical uses for someone seeking romance, do these results tell us something about the nature of personality? According to advocates of evolutionary personality theory, the answer is “Yes.” These psychologists think of romantic relationships in terms of male and female members of a species getting together to (eventually) reproduce. Consequently, choosing a partner is based in part on concerns for parental investment (Geary, 2000; Trivers, 1972). That is, as members of a species, we are concerned about reproducing and passing our genes along to the next generation. Because of this concern, we select mates who are likely to be part of successful reproduction and effective child rearing. This analysis does not suppose that we actively consider reproduction success when we select among potential dating partners but that certain mate-selection preferences have been passed down to us through the evolutionary process. According to this view, men and women have different ideas about parental investment. Because they bear and in most cases raise the offspring, females are more selective about whom they choose to mate and reproduce with. In contrast, in many species, males are free to attempt to reproduce with as many females as they can. Frequent mating with many different females increases the probability that the male will pass his genes to the next generation. In evolutionary terms, the investment in selecting a mate is larger for women than for men. She has more to lose by making a poor choice than he does. Because they have different ideas about parental investment, evolutionary personality theory predicts that men and women look for very different characteristics in their partners. What do men look for in a woman? What do women want in a man? Complete answers to these commonly asked questions have eluded the most insightful of us. 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. Evolutionary Personality Theory and Mate Selection 243 Although they cannot explain everything, evolutionary personality psychologists argue that men and women select their mates based in part on what serves the needs of the species. As described in the next section, research supports many of these speculations. What Men Look for in Women From an evolutionary perspective, men can best serve the needs of the species by reproducing as frequently as possible (Buss, 1991). Consequently, men should be attracted to women with “high reproductive value.” In other words, a man should select a woman who is likely to give him many children. But what outward signs do we have of a woman’s likely fertility? One indicator is the woman’s age. A young wife has the potential to produce more offspring than an older wife. Thus, some evolutionary personality psychologists predict that men prefer younger women to older women. Moreover, physical features associated with young adult women, such as “smooth skin, good muscle tone, lustrous hair, and full lips,” provide “cues to female reproductive capacity” (Buss, 1991, p. 2). Not coincidentally, these physical attributes are the ones our society typically associates with beauty. Evolutionary personality psychologists thus predict that men prefer partners who are physically attractive and probably younger than they are. But can the same reasoning be applied to women? Probably not. If anything, a young man is probably less likely than an older man to provide a woman and her offspring with the kinds of material resources she seeks from a partner. As a result of these different preferences for men and women, we would expect most couples to consist of an older husband and a younger wife. Research tends to support this speculation. A national survey of unmarried American adults found that men preferred younger women as potential marriage partners, whereas women expressed a preference for older men (Sprecher, Sullivan, & Hatfield, 1994). Married couples in one study were asked about the importance they placed on various characteristics when choosing their spouse (Buss & Barnes, 1986). As expected, husbands were more likely than their wives to rate physically attractive and good looking as features they sought in a marriage partner. Another study found the more attractive their partner, the more efforts men make to maintain their relationship (Buss & Shackelford, 1997). Men are more likely than women to be satisfied with their marriages when their partner is physically attractive (Meltzer, McNulty, Jackson, & Karney, 2014) and are more upset if their partner becomes less attractive (Cramer, Manning-Ryan, Johnson, & Barbo, 2000). The importance of a woman’s physical attractiveness can also be seen in the tactics women use to gain a man’s attention (Buss, 1988). Evolutionary personality theorist refer to this process as intrasexual selection—the competition among members of one gender for mating access to the best members of the other gender. If men select partners who are youthful and beautiful, a woman can improve her chances of pairing up with the most desirable partner by emphasizing these attributes. To test this possibility, newlyweds in one study were asked to describe what they did to attract their spouse when they first began dating (Buss, 1988). As predicted, the women tended to report that they altered their appearance with makeup and jewelry, wore stylish clothes, wore sexy clothes, and kept themselves clean and groomed. In 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. 244 Chapter 10 / The Biological Approach another study, investigators scheduled undergraduate women to attend experimental sessions on two separate occasions (Durante, Li, & Haselton, 2008). Although the women did not know it, the sessions were scheduled for different times in their ovulatory cycle. Hormone tests verified that one of the visits was on a high-fertility day and the other on a low-fertility day. The women also did not know that the researchers were primarily interested in what they would wear to the session. Consistent with the intrasexual selection notion, the women wore clothes judges rated as more revealing and sexier on high-fertility days. These were the days in which the women were said to be more interested in capturing the attention of a potential partner. Other studies find that women are more likely to wear red or pink on high-fertility days, presumably to appear more sexually appealing (Beall & Tracy, 2013), and are more likely to flirt with attractive men (Cantu et al., 2014). Finally, some evolutionary personality theorists point to the so-called lipstick effect, that is, the tendency for women to spend more money on cosmetics during economic downturns (Hill, Rodeheffer, Griskevicius, Durante, & White, 2012). These researchers argue that economic insecurity heightens the need to find a mate with resources, which drives the women to try to make themselves more attractive. In sum, there is abundant evidence that men are more likely than women to look at physical attractiveness when selecting a dating or marriage partner (Feingold, 1990). However, it is important to keep in mind that it is fertility men are said to be seeking in younger women, not necessarily youthfulness. When one team of investigators interviewed teenage boys, they found a preference for slightly older women (Kenrick, Keefe, Gabrielidis, & Cornelius, 1996). In other words, the boys were attracted to the females most likely to reproduce regardless of their age. Although the findings are consistent, there is one important limitation in the studies reviewed so far. That is, they tell us a lot about the preferences of American men and women, but little about romantic choices in other cultures. To make a strong case for the evolutionary interpretation, we need to demonstrate that this effect is not limited to certain social or cultural groups. For example, if men were found to rely on physical attractiveness only in Western cultures, a strong argument could be made that this behavior reflects social learning patterns rather than an inherited human characteristic. To address this problem, one team of researchers conducted an elaborate crosscultural investigation (Buss, 1989). The researchers looked at gender differences in partner preferences in 37 cultural groups. These groups were located in 33 different countries, on six continents and five islands, and included people from cultural backgrounds very different from Americans, such as South African Zulus, Gujarati Indians, and Santa Catarina Brazilians. Participants in each of these samples were asked what they considered the ideal age for themselves and their partner when marrying. Participants were also asked how important each of 18 personality traits were for choosing a potential mate (e.g., intelligence, good financial prospect, and good looks). The findings support the evolutionary position. As shown in Table 10.5, in each of the 37 samples, men preferred partners who were younger than they were. Additional evidence was found when researchers looked at the actual age at which people first married. This information was available in 27 of the countries studied. Men in each of these cultures not only said they preferred younger partners but also tended to 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. Evolutionary Personality Theory and Mate Selection 245 Table 10.5 Mean Age Difference in Years Between Preferred Age of First Marriage for Spouse and for Self in 37 Cultures Sample Males Females Nigeria −6.45 4.90 South Africa (Whites) −2.30 3.50 South Africa (Zulus) −3.33 3.76 Zambia −7.38 4.14 China −2.05 3.45 India −3.06 3.29 Indonesia −2.72 4.69 Iran −4.02 5.10 Israel (Jewish) −2.88 3.95 Israel (Palestinian) −3.75 3.71 Japan −2.37 3.05 Taiwan −3.13 3.78 Bulgaria −3.13 4.18 Estonia −2.19 2.85 Poland −2.85 3.38 Yugoslavia −2.47 3.61 Belgium −2.53 2.46 Finland −0.38 2.83 France −1.94 4.00 Germany −2.52 3.70 Great Britain −1.92 2.26 Greece −3.36 4.54 Ireland −2.07 2.78 Italy −2.76 3.24 Africa Asia Eastern Europe Western Europe (Continued) 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. 246 Chapter 10 / The Biological Approach Table 10.5 Mean Age Difference in Years between Preferred Age of First Marriage for Spouse and for Self in 37 Cultures (Continued) Sample Males Females Netherlands −1.01 2.72 Norway −1.91 3.12 Spain −1.46 2.60 Sweden −2.34 2.91 Canada (English) −1.53 2.72 Canada (French) −1.22 1.82 United States (Mainland) −1.65 2.54 United States (Hawaiian) −1.92 3.30 Australia −1.77 2.86 New Zealand −1.59 2.91 Brazil −2.94 3.94 Colombia −4.45 4.51 Venezuela −2.99 3.62 Mean −2.66 3.42 North America Oceania South America Note: Negative values indicate a preference for a younger mate; positive values indicate a preference for an older mate. Source: Buss, D. M. (1989). Sex differences in human mate preferences: Evolutionary hypotheses tested in 37 cultures. Behavioral and Brain Sciences, 12, 1–49. Reprinted by permission of the author and Cambridge University Press. marry women younger than themselves. Although the investigators made no predictions about the women’s preferences, the women in all 37 cultures said they preferred an older partner. More evidence for the evolutionary personality position was found when the researchers looked at the importance men and women placed on physical attractiveness when selecting a mate. In each of the cultures, men were more likely than women to say that good looks are important. This difference was statistically significant in all but three of the samples. Thus the tendency for men to prefer youthful and physically attractive women appears to be fairly universal despite differences in cultures and social norms. Evolutionary personality psychologists interpret these findings as evidence for universal characteristics handed down from our ancestors. 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.