Advances in Personality Science (II)

I like this book, it’s quite good. Some more quotes:

“Perhaps one of the most useful contributions of understanding the patterns of regional brain activity that characterize personality traits and clinical syndromes is the potential insight it provides into individual differences in cognitive capabilities and styles. Numerous studies have shown that activity in regions of the cortex specialized for particular modes of information processing predicts performance on tasks that benefit from that type of computation. In the vast majority of studies […] increased activity is associated with better performance, whereas deficient activity is associated with decrements in performance. […] Both anxious apprehension and anxious arousal types of anxiety, as well as depression, are characterized by specific cognitive biases and impairments […] Anxiety in general has been strongly associated with an attentional bias to threatening stimuli […] We have argued that these attentional biases toward threat-related stimuli dovetail with specializations of the right posterior region for visual and spatial attention, vigilance, and autonomic arousal, reflecting the activity of an emotional surveillance system (Nitschke et al., 2000). Our recent fMRI research suggests that this area may include temporal, parietal, and occipital regions of the right hemisphere (Compton et al., 2001; Miller, 2000). […] In depression, deficits have been described for explicit memory, executive functions, and visuospatial skills […] We have argued that decreased activity in prefrontal brain regions can account for many of the cognitive impairments in depression, including memory for material on tasks that require or benefit from information-organizing strategies, the ability to access errors accurately, problem solving, and cognitive flexibility. Depression has also been consistently associated with impairments on tasks associated with right posterior regions of the brain (e.g., Deldin, Keller, Gergen, & Miller, 2000; Keller et al., 2000; for review of earlier studies, see Heller & Nitschke, 1997). These findings are consistent with evidence that there is decreased activity in these brain regions (Banich et al., 1992; Liotti & Tucker, 1992; Otto, Yeo, & Dougher, 1987).” (from chapter 4)

“Schmidt (1999) reported that left and right anterior brain activity is differentially associated with sociability and shyness, respectively. From an incentive–threat perspective, sociability reflects an incentive-oriented view of other individuals (often major sources of reward), whereas shyness reflects a threat-oriented view of others (often, also, major sources of punishment). […] Henriques and Davidson (1990, 1991) have shown that currently or previously depressed individuals (i.e., those who present a significant lack of incentive motivation) exhibit relatively less resting left frontal activity. In summary, there is a substantial set of studies demonstrating links between left- and right-sided anterior cortical activity with incentive and threat motivation sensitivity, respectively. […] Given that one component of motivation is the detection, selection, and orientation toward incentives and threats, it appears likely that individual differences in the strength of these two systems would influence information processing in a way that is consistent with the stronger of the two systems under circumstances in which other factors are controlled for. [This hypothesis has been tested and it holds, at least to some extent. Such biological differences may be used to explain part of the inter-individual variation in e.g. risk preferences – US.]” (from chapter 5)

“In the models of development as they are related to personality, we use a combination of approaches. Here I consider three models of the development of personality: a trait or status model, a contextual or environmental model, and an interactional model. […] The trait or status model is characterized by its simplicity. It holds to the view that a trait, or the status of the child at one point in time, is likely to predict a trait or status at a later point in time. A trait model is not interactive and does not provide for the effects of the environment. In fact, in the most extreme form, the environment is thought to play no role either in effecting its display or in transforming its characteristics. A particular trait may interact with the environment, but the trait is not changed by that interaction. […] The prototypic environmental model holds that exogenous factors influence development. Two of the many problems in using this model are (1) our difficulty in defining what environments are and (2) the failure to consider the impact of environments throughout the lifespan. In fact, the strongest form of the developmental environmental or contextual model argues for the proposition that adaptation to current environment throughout the life course has a major influence on our behavior and on our personalities. Moreover, such a model is familiar to students of personality because it represents the idea that context, to a large degree, determines behavior. As environments change, so too does the individual (Lewis, 1997). This dynamic and changing view of environments and adaptation is in strong contrast to the earlier models of environments as forces that act on the individual and that act on the individual only in the early years of life. […] in the study of personality development, even though we recognize that environments can cause both normal and abnormal behavior, we prefer to treat the person—to increase coping skills or to alter specific behaviors—rather than to change the environment (Lewis, 1997). Yet we can imagine the difficulties that are raised when we attempt to alter specific maladaptive behaviors in environments in which such behaviors are adaptive […] The general environmental model that I have suggested (Lewis, 1997) holds that children’s behavior always is a function of the environment in which the behavior occurs, because the task of the individual is to adapt to its current environment.1 As long as the environment appears consistent, the child’s behavior will be consistent; if the environment changes, so, too, will the child’s behavior. It is the case that maladaptive environments produce both normal and abnormal behavior. From a developmental point of view, I would hold that maladaptive behavior is caused by maladaptive environments; if we change those environments, we may be able to alter the behavior. […]

Although the trait model is most often used in research, the interactional model is usually held to be the one which, from a theoretical point of view, is most likely to account for the development and change in personality. This mismatch between theory and research has serious implications for the growth of our knowledge about human development. Interactional models vary; some researchers prefer to call them “interactional” and others “transactional” (Lewis, 1972; Sameroff & Chandler, 1975). All these models have in common the role of both child and environment in determining the course of development. In these models, the nature of the environment and the characteristics or traits of the child are needed to explain concurrent, as well as subsequent, behavior and adjustment. Such models usually require an active child and an active environment; however, they need not do so. What they do require is the notion that behavior is shaped by its adaptive ability and that this ability is related to environments. Maladaptive behavior may be misnamed because the behavior may be adaptive to a maladaptive environment. […] Although there is some evidence in the developmental literature for an interactional approach, the data are not that strong (Lewis, 1999c). Moreover, without a consideration of the environment over time, it is still relatively unproven whether any interactional model accounts for more of the variance than does an environmental model alone. As is discussed subsequently, without the proper environmental measurement, any serious test of the various developmental models is not possible. […]

earlier traits or characteristics have little relation to later personality characteristics and […] the concurrent environment is most predictive of these characteristics. These results, in general, hold across most longitudinal studies. It has been labeled a simplex pattern, as prediction grows weak as the two age points increase in time. […] I have approached the topic of continuity and discontinuity of personality characteristics by looking at the data in the early period of the lifespan. How do the data for the earlier part of the lifespan, the first two dozen years, agree with the data obtained across the whole lifespan? There appears to be general agreement that the correlations (or stability) of personality characteristics are quite low for the first 30–40 years of life but become stronger at later ages (Caspi & Roberts, 2001). This is explained in such terms as crystallization (Caspi & Roberts, 2001) […] As a field, we have argued for a very powerful hypothesis. We have argued that personality characteristics of individuals are enduring across time and context. In this chapter, I have raised the question of whether or not the data from the past 75 years of development and study supports this powerful hypothesis. It is not supported in the first third of life, and the correlations are, overall, rather weak for the rest of the lifespan.” (from chapter 6)

“From biological perspectives, phenotypic (and thereby genotypic) variability is the raw material on which natural selection operates. Selection in general is seen as a homogenizing force that culls less optimal variants in favor of those that foster survival and reproduction (Willams, 1966). Members of any population differ from one another in what is seen as largely inconsequential ways; individual differences are noise in the evolutionary process that results from nonselective mechanisms such as mutation, recombination, and drift. Studies in evolutionary psychology accordingly focus on topics such as mate selection, with little consideration for individual-difference variables […] This species-general approach to evolutionary psychology confronts long-held beliefs in other fields of psychology that individual differences are anything but inconsequential. Personality theorists, for example, have long shown how individual differences are related to adaptation across the lifespan. Only more recently has it been suggested that these differences are themselves related to reproductive success […] Work in behavioral genetics has shown that a good portion of this variation in personal characteristics is heritable Heritability is often considered to support evolutionary arguments, as “adaptations” must have a genetic component. Paradoxically, however, the more the variability in a population on a certain trait is due to genetic differences (i.e., heritability), the less likely it is that the trait is an “adaptation.” Naturally selected adaptations tend to have by definition very low heritabilities because there is little variation across individuals (e.g., a four-chambered heart). In other words, “heritable diversity is inversely proportional to adaptive importance” (Tooby & Cosmides, 1990, p. 49). [This is not news to me, but this is an important point perhaps not all readers are familiar with – US] […]

Similar to several personality theories, theories of motivation […] and models of social competence […] resource control theory has the balancing of self and other goals at its core. This theoretical perspective is based on the assumption that humans, like other social species, should optimally behave in ways that facilitate personal resource acquisition while at the same time maintaining friendly bonds with other group members. The necessity of meeting one’s needs and simultaneously being a good group member underlies the evolution of much of human behavior and psychological organization: It implies that individuals must balance being egoistic and other-oriented […] the presence of others intensifies intragroup competition for the very resources that the group acquires. In other words, “cooperative” relationships are inevitably contaminated by competition. […]

McGuire and associates […] have demonstrated that hierarchy ascendance is associated with serum serotonin elevations (Brammer, Raleigh, & McGuire, 1994; McGuire, Raleigh, & Brammer, 1984). In the presence of others, top-ranked male vervets had higher than average serotonin levels. When removed from the group, they returned to normal levels (i.e., dominance requires the presence of others). In the absence of the reigning alpha, a new male rose in the hierarchy and, accordingly, enjoyed elevated serotonin until the reigning male returned. The authors concluded that elevated serotonin was both a cause and effect of successful ascendance. The effects of serotonin on mood and behavior are well known: Low levels of serotonin are associated with low self-esteem, anxiety, and depression. Pharmacologically enhanced serotonin (e.g., serotonin reuptake inhibition) decreases anxiety and increases sociability and assertiveness […] In a similar vein, social subordinance in nonhuman primates has been linked with hypercortisolism, an exaggerated stress response (Sapolsky, Alberts, & Altmann, 1997). […]

Shahar, Grob, and Little (2001) examined the relationship between depression and the reported attainment of the goal of achieving an intimate relationship. In young adulthood (ages 18–39), there were no differences on depression—males and females who either had or had not achieved intimate-relationship status were similar in their low levels of depressive symptomology. In mid-age, on the other hand, substantial gaps appeared to emerge; in fact, all four groups differed. Males who had not attained intimate-relationship status showed the highest levels of depression, followed by females who had not, then males who had, and then females who had. By old age, the gender differences disappeared, but the effect of either having attained or not having attained an intimate relationship was pronounced. Those persons who had not established an intimate relationship reported greater depressive symptoms than those who had achieved intimacy with another person.” (from chapter 7)

“Most studies assume that genetics and individual family environment represent the only two influences on personality traits. […] [Many] authors seem to assume that the environment stops at the door of the family home. As many theorists and researchers have argued, the larger sociocultural environment can have a substantial effect on personality and development […] Examining “nonshared” environment (Plomin & Daniels, 1987) does not solve this problem, because twins (identical or fraternal) are necessarily the same birth cohort; thus the larger sociocultural environment is still “shared” environment (but “shared” environment outside of the family). Thus birth cohort might be a nongenetic explanation for the similarity between identical twins raised apart. […] The fact that twins share a birth cohort also means that these studies have likely overestimated the heritability estimates for personality traits. Almost all of the studies examining genetic and environmental effects on personality have included samples of only one birth cohort (or samples very close in birth cohort). If more cohorts were included, then the variance in personality would likely increase. […]

Working with my colleague Keith Campbell, I performed a metaanalysis on college students’ scores on the Rosenberg Self-Esteem Scale (RSE) between 1968 and 1994. We found that college students’ self-esteem scores increased about two thirds of a standard deviation over this 26-year period (Twenge & Campbell, 2001). Thus 1990s college undergraduates scored considerably higher in self-esteem than had their late-1960s counterparts. It is possible that today’s undergraduates actually do feel better about themselves compared with the college students of the 1960s. It could also be that college students now speak the language of self-esteem and understand that one is supposed to possess copious amounts of this supposedly precious substance. […] In sum, the societal trend has been toward meeting new people more often and toward more fluid and changeable relationships. In this world, being extraverted is no longer a quirk of genetics; it is a virtual requirement (e.g., Whyte, 1956). When you are expected to leave your birth family at a young age and create an entirely new support system of your own, being outgoing becomes essential. Extraversion, in its classic form, is not simply about liking to be with people; it is about liking to be with many people (such as at a party) and being comfortable meeting new people. In modern society, both family and career depend, at least in part, on being extraverted. The available evidence suggests that extraversion began to increase in American college students beginning in the late 1960s. In a recent paper (Twenge, 2001a), I found that American undergraduates scored 0.79 to 0.97 standard deviations higher on extraversion scales in 1993 than in 1966 (the measures were the Extraversion scales of the Eysenck Personality Inventory and the Eysenck Personality Questionnaire). […] During the most recent time period included in [Twenge, 2001b], sex differences in assertiveness decreased from a male advantage of 0.40 standard deviations in 1968 to no difference (d = –.07) in 1993. Thus assertiveness, once a solid sex difference favoring men, is now a personality trait with no discernible differences between men and women.” (from chapter 8)

March 31, 2013 - Posted by | Books, Evolutionary biology, Genetics, Psychology

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