CH-4-6 Theoretical and Measurement Issues in Trait Psychology – Personality Psychology: Domains of Knowledge About Human Nature : Chapter Notes

This Document Contains Chapters 4 to 6 Chapter 4 Theoretical and Measurement Issues in Trait Psychology Chapter Outline Theoretical Issues Meaningful Differences Between Individuals There are meaningful differences between individuals (trait psychology is also called differential psychology) People differ in amounts of traits, and differences can be accurately measured According to trait psychologists, every personality is the product of a combination of a few basic, primary traits Consistency Over Time Research indicates consistency over time for broad traits Although consistent over time, how a trait is manifested in behavior might change over time How can there be consistency in a trait if it is known to change with age (e.g., impulsivity)? Focus on the rank order differences between people
Consistency Across Situations Trait psychologists traditionally assumed cross-situation consistency If situations mainly control how people behave, then the existence or relevance of traits is questionable Hartshorne and May (1928): Low cross-situation consistency is in honesty, helpfulness, self-control Mischel (1968): Personality psychologists should abandon their efforts to explain behavior with traits, focusing instead on situations Situationism: If behavior varies across situations, then situational differences and not personality traits determine behavior Mischel’s (1968) critique encouraged debate in personality psychology about the importance of traits compared to situations in causing behavior Both sides tempered views: Trait psychologists acknowledged the importance of situations, and situationists acknowledged the importance of traits Debate led to two lasting changes: Focus on person-situation interaction and practice of aggregation Person-Situation Interaction Two possible explanations for behavior: Behavior is a function of personality traits Behavior is a function of situation Integration: Personality and situation interact to produce behavior Differences between people make a difference only under certain circumstances Situational specificity: Certain situations can provoke behavior that is out of character for an individual Strong situation: Situations in which most people react in a similar way (e.g., grief following loss of loved one) When situations are weak or ambiguous, personality has its strongest influence Three additional ways in which personality and situation interact to produce behavior Selection: Tendency to choose or select situations in which one finds oneself, as a function of personality Evocation: Certain personality traits may evoke specific responses from others Manipulation: Various means by which people influence the behavior of others; tactics of manipulation vary with personality Aggregation Longer tests are more reliable than shorter ones and are better measures of traits Single behavior or occasion may be influenced by extenuating circumstances unrelated to personality Aggregation implies that traits are only one influence on behavior Aggregation also implies that traits refer to the person’s average level Thus, personality psychologists will never be good at predicting single acts or single occasions Measurement Issues Trait approach relies on self-report surveys to measure personality Personality psychologists assume that people differ in the amounts of various traits, so a key measurement issue is determining how much of trait person has Traits are often represented as dimensions along which people differ Trait psychologists are aware of and address circumstances that affect accuracy, reliability, validity, and utility of self-report trait measures Carelessness Method for detecting such problems is an infrequency scale embedded in test Infrequency scale contains items that most people answer in a particular way If a participant answers differently than most, this suggests carelessness Another method for detecting carelessness is to include duplicate items spaced far apart in the survey—if the person answers the same item differently, this suggests carelessness Faking on Questionnaires “Fake good”: Attempt to appear better off or better adjusted than one is “Fake bad”: Attempt to appear worse off or less adjusted than one is Method to detect is to a devise scale that, if answered in particular way, suggests faking Beware of Barnum Statements in Personality Test Interpretations Barnum statement: generality that could apply to anyone Personality and Prediction Applications of Personality Testing in the Workplace Whether someone does well in an employment setting may be determined, in part, by whether a person’s personality traits mesh with job requirements Personality traits may predict who is likely to do well in particular a job, so it makes sense to select people for employment based on measures of traits Legal Issued in Personality Testing in Employment Settings But using tests to select employees has limitations and potential liabilities Lawsuits have challenged the use of tests on the grounds ranging from discrimination, to invasion of privacy, to freedom of religion Most employers receive overall test scores; however, not the applicant’s answers to specific questions In 1978, the EEOC standardized federal guidelines for the use of tests in employment selection Two main concerns that the employer must satisfy to use for employment selection Test must predict performance on a specific job or jobs like the ones people are being selected for Test must not be biased or have “undue impact” on persons from protected groups, such as women and minorities Personnel Selection—Choosing the Right Person for the Job Personality tests frequently used to screen out “wrong” individuals from a pool of applicants for police officers Minnesota Multiphasic Personality Inventory (MMPI) California Personality Inventory (CPI) 16 Personality Factor (16PF) Questionnaire Selection in Business Settings—The Myers-Briggs Type Indicator (MBTI) MBTI is most widely used personality assessment device in business settings Assesses eight fundamental preferences, which reduce to four scores: Extraverted versus introverted Sensing or intuitive Thinking or feelings Judging or perceiving Four scores combined to yield 16 types MBTI used widely to select applicants for leadership positions But criticism, especially regarding reliability and predictive validity Selection in Business Settings—The Hogan Personality Inventory (HPI) Hogan conducted research to identify aspects of personality important in business settings Developed theory about social aspects of personality important in business, concluding that dominant themes are motive to get along with others and motive to get ahead In business settings, people work in groups, and people in groups have three key wants: acceptance, status and control of resources, and predictability. Developed HPI to assess traits of Big Five relevant to three key wants SUMMARY AND EVALUATION Hallmark of trait perspective is the emphasis on the differences between people Trait psychologists assume that people will be relatively constant over time and across situations in behaviors, because of their differences in various traits Traits are more likely to influence a person’s behavior when the situation is weak and ambiguous and doesn’t push for conformity from all people Personality traits refer to the average tendencies in behavior Trait psychologists are interested in the accuracy of measurement Interest in measurement and prediction has led trait psychologists to apply these skills to the selection or screening of job applicants and other situations where personality might make a difference KEY TERMS Differential Psychology Social Desirability Consistency Integrity Tests Rank Order Personnel Selection Situationism Negligent Hiring Person-Situation Interaction Female Underprediction Effect Aggregation Title VII of the Civil Rights Act of 1964 Situational Specificity Griggs v. Duke Power Strong Situation Uniform Guidelines on Employee Selection Situational Selection Procedures Evocation Ward’s Cove Packing Co. v. Atonio Price Waterhouse v. Hopkins Disparate Impact Infrequency Scale Race or Gender Norming Faking Americans with Disabilities Act (ADA) False Negative Right to Privacy False Positive Job Analysis Barnum Statements Myers-Briggs Type Indicator (MBTI) Psychological Types Hogan Personality Inventory (HPI) Chapter Overview This chapter introduces students to key theoretical and measurement issues in trait psychology. The authors begin with a review of several important theoretical issues, including a review of the key assumptions that most trait psychologists share. These include that there exist meaningful differences between individuals, and that these differences are stable across time and across some situations. The authors review the history of trait psychology, noting that a heavy emphasis on the primacy of traits in explaining behavior has now been tempered with the recognition that situations and traits interact to produce behavior. The authors review three key ways in which traits and situations interact to produce behavior, including situation selection, evocation of responses from others, and manipulation of others. Another lasting change in trait psychology caused by the challenges of situationists is the reliance on aggregation to measure the average tendencies of individuals. Aggregation refers to averaging several single observations and produces a more reliable measure of a personality trait than a single observation. Next, the authors review several key measurement issues in trait psychology, including carelessness, faking, and response sets. One such response set that has received a great deal of theoretical and empirical attention is socially desirable responding. The authors next review the use of trait measures to predict performance, including the use of trait measures in employment selection and educational selection. A key problem reviewed by the authors in using trait measures to predict performance is the restriction of range. This occurs when the range of one or both variables being correlated is restricted, producing a smaller correlation than would be the case if no range restriction occurred. Learning Objectives Identify and discuss three assumptions about personality traits that most trait psychologists share. Define and discuss situationism. Provide an example of a situationist interpretation of individual behavioral differences. Discuss the idea of person-situation interaction. Provide an example of an interactionist interpretation of individual behavioral differences. Define and give an example of situational specificity. Define and give an example of a strong situation. Discuss and give examples of selection, evocation, and manipulation as ways in which traits and situations can interact to produce behavior. Discuss aggregation and why it is now a standard practice among trait psychologists. Discuss the measurement issue of careless responding and how trait psychologists might address this problem. Discuss the measurement issue of faking and how trait psychologists might address this problem. Discuss the measurement issue of response sets and how trait psychologists might address this problem. Discuss the two major views of socially desirable responding among trait psychologists. Discuss the application of trait measures to employment selection. What are some of the benefits and liabilities of using traits measures for employment selection? Define and discuss the “criterion problem” that one faces when attempting to use trait measures to predict real-world behavior. Define and discuss “restriction of range” as a problem one can face when attempting to use trait measures to predict real-world behavior. Discuss integrity testing as a means of employment selection. Lecture Topics and Lecture Suggestions Training the Scientists and Engineers of Tomorrow: A Person-Situation Approach (Cross, 2001). This lecture is designed to provide students with an example of how one might conduct research informed by the perspective that behavior is the product of the interaction between personality and situations. This is an interesting study that includes an assessment of sex differences. The topic of sex differences is a reliable attention-grabber for students and is a good way to maintain student interest and appreciation for the importance of the interactions between personality and situations in explaining behavior. Use this lecture as a springboard for discussing the interaction between personality traits and situations in generating behavior. For instructors interested in generating controversial discussion, encourage students to discuss the possibility that sex (male, female) might be appropriately considered a personality variable, or at least an important individual difference. For particularly sharp controversy, encourage students to consider whether sex should be used as a means of selecting applicants for particular jobs—why or why not? Do students agree that employment selection on the basis of sex should be illegal? According to Cross (2001), the United States may face a shortage of well-trained scientists and engineers in the near future. This prospective study examined the issue of women’s low rates of participation in these fields from a person-situation perspective, focusing on the early years of graduate school. 63 graduate students completed questionnaires their first year of graduate school, and at follow-up a year later. Results Although men and women were similar in many respects (e.g., in Graduate Record Exam scores and grades), women evaluated their abilities related to intelligence lower than did men. There were no gender differences in students’ perceptions of the academic climate. Longitudinal analyses revealed that students’ self-evaluations and gender moderated the effects of perceived supportiveness of their academic departments on changes in well-being from the end of their first year to the end of their second year. Reference: Cross, S. E. (2001). Training the scientists and engineers of tomorrow: A person-situation approach. Journal of Applied Social Psychology, 31, 296–323. Managerial Personality and Performance: A Semi-Idiographic Approach (Chatman, Caldwell, & O’Reilly, 1999). This lecture is designed to provide students with an example of how personality can be used to predict performance in a real-world setting. This study investigated whether personality traits can predict managerial performance. Students will find this study interesting, as it speaks to the likelihood that they will find and maintain employment on the basis of personality traits. Use this lecture as a springboard for discussing the relationships between personality traits and job performance, and for discussing the error in predicting job performance on the basis of personality traits. According to Chatman et al. (1999), understanding the relationship between personality and behavior requires accounting for a broad set of traits within each person and the demands of a specific role or situation. To address these requirements, the authors assessed the relevance or ordering of traits within an individual (an idiographic approach) and compared these orderings across individuals occupying similar organizational situations (a nomothetic approach). The utility of this semi-idiographic approach is illustrated with a longitudinal study of 83 MBA students. The MBA students whose personalities were more similar to a template of the successful young manager: Received more job offers upon graduating and, subsequently: Earned higher salaries Were more likely to be working full-time Had changed jobs less often than did those who fit the managerial template less well Reference: Chatman, J. A., Caldwell, D. F., & O’Reilly, C. A. (1999). Managerial personality and performance: A semi-idiographic approach. Journal of Research in Personality, 33, 514–545. Classroom Activities and Demonstrations Larsen and Buss note that, although a trait might be consistent over time, how it manifests itself in actual behavior might change substantially. Consider the trait of disagreeableness. As a child, a highly disagreeable person might be prone to temper tantrums and fits of breath holding, fist pounding, and undirected rage. As an adult, a disagreeable person might be difficult to get along with, and hence might have trouble sustaining interpersonal relationships and holding down a job. Distribute Activity Handout 4–1 (“Trait Consistency, but Behavioral Variability”). Give students about five minutes to complete the handout. Ask several students to volunteer their responses. Use this activity as a springboard for discussing the idea that trait consistency does not mean behavioral invariance, the fact that different behaviors can be generated by the same underlying traits, and the interaction between traits and situations as a means of accounting for trait consistency in the face of behavioral variability. Larsen and Buss note that one common method for detecting carelessness of participants who complete a personality inventory is to design and incorporate an infrequency scale into the measure. An infrequency scale includes items that most or all people would answer in a particular way. Distribute Activity Handout 4–2 (“Designing an Infrequency Scale”) to students. Give students five minutes to complete the handout. Ask several students to volunteer a few of the items they wrote. Use this activity as a springboard for discussing the use of infrequency scales for detecting carelessness in responding. Larsen and Buss discuss how measures of personality traits have been used in employment selection and educational selection. This activity will give students an opportunity to identify 10 traits that they think might be used to identify and select applicants for admission as an undergraduate into a university or college. Distribute Activity Handout 4–3 (“Selecting Applicants for Admission to Undergraduate Education”). Give students five minutes to complete the handout. Ask several students to volunteer a few of the traits they identified, and to explain briefly why they identified those particular traits. Use this activity as a springboard for discussing the use of personality measures to predict performance in the real world and, in particular, for selecting applicants into educational programs. Chapter 5 Personality Dispositions Over Time: Stability, Coherence, and Change Chapter Outline Conceptual Issues: Personality Development, Stability, Coherence, and Change What Is Personality Development? Personality development: Continuities, consistencies, stabilities in people over time, and the way in which people change over time Rank Order Stability Maintenance of an individual’s position within group Mean Level Stability Constancy of level in population Personality Coherence Maintaining rank order relative to others but changing in the manifestations of trait Personality Change Two defining qualities Internal: Changes are internal to a person, not changes in the external surrounding Enduring: Changes are enduring over time, not temporary Three Levels of Analysis Population level: Changes or constancies that apply more or less to everyone Group differences level: Changes or constancies that affect different groups differently Sex differences Cultural or ethnic group differences Individual differences level: e.g., Can we predict who is at risk for psychological disturbance later in life based on earlier measures of personality? Personality Stability Over Time Stability of Temperament During Infancy Temperament: Individual differences that emerge very early in life, are heritable, and involved behaviors are linked with emotionality As assessed by caregivers, temperament factors include activity level, smiling and laughter, fear, distress to limitations, soothability, and the duration of orienting Research points to the following conclusions Stable individual differences emerge early in life, where they can be assessed by observers For most temperament variables, there are moderate levels of stability over time during the first year of life Stability of temperament is higher over short intervals of time than over long intervals of time Level of stability of temperament increases as infants mature
Stability During Childhood Longitudinal study: Investigation of same group of individuals over time Block and Block Longitudinal Study: Study of 100 children assessed at 3, 4, 5, 7, and 11 years One study using Block and Block Longitudinal Study: Individual differences in activity level Activity level assessed in two ways: Using actometer and independent assessments of behavior and personality provided by teachers Stability coefficients: Correlations between same measures obtained at two different points in time (test-retest reliability) Validity coefficients: Coefficients between different measures of the same trait at the same time Actometer measurements of activity level had positive validity coefficients with teach measurements of activity level: Thus, activity level in childhood can be validly assessed with measures Activity level measurements are all positively correlated with measures of activity level taken at later ages: Activity level shows moderate stability during childhood Size of correlations decreases as the time interval between different testings increases Stability of childhood aggression Individual differences in aggression emerge early in life, by 3 years Individuals retain rank order stability on aggression over many years Stability coefficients decline as interval between two times of measurement increases Rank Order Stability in Adulthood Across different self-report measures of personality, conducted by different investigators, over differing time intervals (3 to 30 years), broad personality traits show moderate to high levels of stability Average correlations across traits, scales, and time intervals is about +.65 Stability also found using spouse-report and peer-report Personality consistency tends to increase in stepwise fashion with increasing age—personality appears to become more and more “set in plaster” with age
Mean Level Stability in Adulthood “Big five” personality factors show a consistent mean level stability over time Especially after 50, very little change in the average level Small but consistent changes, especially during the 20s Openness, extraversion, neuroticism decline with age until 50 Conscientiousness and agreeableness show gradual increase with time Personality Change Changes in Self-Esteem from Adolescence to Adulthood Transition from early adolescence to early adulthood appears to be harder on women than on men, in terms of the criterion of self-esteem Females tend to decrease in self-esteem, males tend to increase in self-esteem Appears to be a coherent set of personality variables linked with changes in self-esteem over time for each sex Autonomy, Dominance, Leadership, and Ambition Longitudinal study of male managerial candidates, first when men were in their 20s and then followed them up periodically over a 20-year span, when men were in their 40s Steep decline in ambition—steepest during first eight years, but continued to drop over next 12 years Supplementary interviews suggested that men became more realistic about limited possibilities for promotion in a company But note that autonomy, leadership motivation, achievement, and dominance increased over time Sensation Seeking Increases with age from childhood to adolescence Peaks in late adolescence, around ages 18–20 Falls more or less continuously with age after the 20s Femininity Mills College Study: Longitudinal study of women from an elite college examined personality changes between the early 40s and early 50s Consistent drop in femininity from the early 40s to early 50s Drop was not related to menopause per se Perhaps attributable to decreases in the levels of estrogen
Independence and Traditional Roles In Mills’s study, women were assessed for independence (self-assurance, resourcefulness, competence, distancing self from others, not bowing to conventional demands of society) at 21 and again at 43 For divorced mothers, nonmothers, and working mothers, independence increased over time Only traditional homemakers showed no increase in independence over time These results highlight utility of examining sub-groups within a sample Personality Changes Across Cohorts: Assertiveness and Narcissism Cohort effects: changes (for example, in personality) over time that are attributable to living in different time periods rather than to “true” change Research by Jean Twenge Personality Coherence Over Time: Prediction of Socially Relevant Outcomes Personality coherence: Predictable changes in manifestations or outcomes of personality factors over time, even if underlying characteristics remain stable Marital Stability, Marital Satisfaction, and Divorce (Kelly and Conley, 1987) Longitudinal study of 300 couples from engagements in 1930s to 1980s During first testing session in 1930s, friends rated each participant’s personality on many dimensions Three aspects of personality strongly predicted marital dissatisfaction and divorce Husband’s neuroticism Husband’s impulsivity Wife’s Neuroticism
Alcoholism, Drug Use, and Emotional Disturbance Personality predicts the later development of alcoholism and emotional disturbance Alcoholic men had lower impulse control scores than men with emotional disturbance Religiousness and Spirituality Education, Academic Achievement, and Dropping Out (Kipnis, 1971) Among low SAT scorers, there is no link between impulsivity and subsequent GPA Among high SAT scorers, high impulsive people had consistently lower GPAs than low impulsive people High impulsive people are more likely than low impulsive people to flunk out of college Health and Longevity Conscientiousness Positive emotionality (extraversion) Low levels of hostility Predicting Personality Change Can we predict who is likely to change in personality and who is likely to remain the same? Caspi and Herbener (1990) studied middle-aged couples over an 11-year period, in 1970 and again in 1981 Researchers asked: Is the choice of marriage partner a cause of personality stability or change? People married to a spouse highly similar to themselves showed most personality stability People married to a spouse least similar to themselves showed most personality change SUMMARY AND EVALUATION Personality development is the study of both the continuities and changes in personality over time Strong evidence for personality rank order stability over time Personality also changes in predictable ways, sometimes in different ways for men and women Personality also shows evidence for coherence over time KEY TERMS Personality Development Longitudinal Studies Rank Order Stability Actometer Mean Level Stability Stability Coefficients Mean Level Change Validity Coefficients Personality Coherence Self-Esteem Temperament Cohort Effects Chapter Overview This chapter provides students with an introduction to stability, change, and coherence of personality dispositions over time. The authors begin by reviewing several key conceptual issues in personality development. They define personality development, then define and differentiate rank order stability, mean level stability, and personality coherence. Next the authors review what should and should not be considered personality change. The authors note that personality change has two defining qualities: The changes are internal to the person, and the changes are enduring over time. The authors then review personality development from the perspective of three levels of analysis: the population level, the group differences level, and the individual differences level. The authors then consider personality stability over time, first addressing stability of temperaments during infancy, then stability during childhood, and then rank order and mean level personality stability in adulthood. The authors next address personality change, beginning with a review of work on changes in self-esteem from adolescence to adulthood. The authors also consider day-to-day changes in self-esteem. The authors then review change during adulthood along with several personality dimensions, including flexibility, impulsivity, ambition, sensation seeking, femininity, competence, and independence. The authors then consider personality coherence over time and the prediction of socially relevant outcomes from personality assessed earlier in life. The socially relevant outcomes include marital dissatisfaction and divorce, alcoholism and emotional disturbance, and education and academic achievement. The authors review work indicating that childhood temper tantrums predict adult outcomes such as criminality. The authors next review work suggesting that the choice of marriage partner predicts personality stability and change. Learning Objectives Define personality development. Define and distinguish three forms of personality stability: Rank-order stability, mean level stability, and personality coherence. Define personality change, including the two key features required for identification of “real” personality change. Identify and discuss the three levels of analysis for considering personality change and stability. Discuss the stability of temperaments during infancy. Discuss personality stability during childhood. Discuss empirical work examining the life trajectories of bullies and whipping boys from childhood to adulthood. Discuss empirical work on rank order personality stability in adulthood. Discuss empirical work on mean level personality stability in adulthood. Discuss work on changes in self-esteem from adolescence to adulthood, and day-to-day changes in self-esteem (self-esteem variability). Discuss empirical work on the changes over time in flexibility and impulsivity. Discuss empirical work on the changes over time in autonomy, dominance, leadership, and ambition. Discuss empirical work on the changes over time in sensation seeking. Discuss empirical work on the changes over time in femininity, competence, independence, and independence, based on the Mills College Study. Discuss the relationship between wife’s personality, husband’s personality, and subsequent marital dissatisfaction and divorce. Discuss the relationship between personality and subsequent alcoholism and emotional disturbance. Discuss the relationship between impulsivity and subsequent educational and academic achievement. Discuss empirical work on the relationships between childhood temper tantrums and adult outcomes such as criminality. Discuss work suggesting that choice of marriage partner predicts personality change and stability over time. Identify and discuss other personality dimensions besides traits that might change over time. Lecture Topics and Lecture Suggestions Two Personalities, One Relationship: Both Partners’ Personality Traits Shape the Quality of Their Relationship (Robins, Caspi, & Moffitt, 2000). This lecture is designed to encourage students to think more about how personality can generate socially relevant outcomes. Students appreciate work at the interface of personality and interpersonal relationships, and this study is particularly well conducted. Use this lecture as a springboard for more in-depth discussion of the impact of personality on socially relevant outcomes, with a special focus on satisfaction and happiness in romantic relationships. Challenge students to consider how the results of this study are consistent or not consistent with similar research presented by Larsen and Buss. Finally, note at the outset of the lecture that there is evidence for the stability of the personality dimensions identified as key predictors of relationship quality in this research. Robins, Caspi, and Moffitt (2000) tested six models of the independent and interactive effects of stable personality traits on each partner’s reports of relationship satisfaction and quality Both members of 360 couples (N = 720) completed the Multidimensional Personality Questionnaire and were interviewed about their relationship Results A woman’s relationship happiness is predicted by her partner’s low negative emotionality, high positive emotionality, and high constraint, whereas A man’s relationship happiness is predicted only by his partner’s low negative emotionality Evidence of additive but not interactive effects: Each partner’s personality contributed independently to relationship outcomes but not in a synergistic way Robins et al. (2000) discuss the results in relation to models that seek to integrate research on individual differences in personality traits with research on interpersonal processes in intimate relationships Reference: Robins, R. W., Caspi, A., & Moffitt, T. E. (2000). Two personalities, one relationship: Both partners’ personality traits shape the quality of their relationship. Journal of Personality and Social Psychology, 79, 251–259. Children’s Self-Reported Psychotic Symptoms and Adult Schizophreniform Disorder: A 15-Year Longitudinal Study (Poulton, Caspi, Moffitt, Cannon, Murray, & Harrington, 2000). This lecture provides students with an example of personality stability and the predictability of adult personality from childhood personality. In this study, the focus is on mental disorders and, in particular, disorders that might be characterized as personality-related. Alternatively, the instructor can present these disorders as characterized by a particular suite of individual differences and, therefore, within the realm of traditional personality psychology. This is a superbly conducted longitudinal study that demonstrates that a suite of psychological and personality aberrations are stable from childhood to adulthood. Use this lecture as a springboard for discussing the issue of personality stability, with a special focus on mental disorders that are related to stable individual differences. Also, the instructor might encourage the discussion of what these results mean for identification and treatment of mental disorders. Poulton et al. (2000) investigated whether self-reported delusional beliefs and hallucinatory experiences at age 11 predicted schizophrenic outcomes 15 years later Participants were members of the Dunedin Multidisciplinary Health and Development Study, born between April 1, 1972, and March 31, 1973, in Dunedin, New Zealand The cohort was assessed at ages 3, 5, 7, 9, 11, 13, 15, 18, 21, and 26 Data are reported from the age 11 (1983–1984) and age 26 assessments (1998–1999) for 761 participants Participants were administered the Diagnostic Interview Schedule for Children for DSM-III at 11 and 26 years old Results Strong linear relationship was found between self-reported psychotic symptoms in childhood and adult schizophreniform disorder (SD) Strong symptom children were 16 times more likely to have an SD diagnosis by age 26 (and individual psychosis symptoms) than were controls 25 percent of the age11 strong symptom participants met the criteria for SD diagnosis by age 26, and almost 70 percent had at least one of either hallucinations, delusions, disorganized speech, catatonia, or anhedonia The strong symptom group was at an increased risk for SD but not for mania or depression at age 26 Reference: Poulton, R., Caspi, A., Moffitt, T. E., Cannon, M., Murray, R., & Harrington, H. (2000). Children’s self-reported psychotic symptoms and adult schizophreniform disorder: A 15-year longitudinal study. Archives of General Psychiatry, 57, 1053–1058. Classroom Activities and Demonstrations Larsen and Buss discuss three important forms of personality stability. These are rank order stability, mean level stability, and personality coherence. Begin by asking for volunteers to define each of these forms of personality stability. Guide students to the following definitions: Rank order stability refers to the maintenance of an individual position within the group; mean level stability refers to constancy of level in a particular group; and personality coherence refers to maintaining rank order in relation to other individuals in a group, but changing the manifestations of the trait. Next, distribute Activity Handout 5–1 (“Three Forms of Personality Stability”). Give students about five minutes to complete the handout. Ask for students to volunteer the examples they used for each of the forms of stability. Use this activity as a springboard for discussing personality stability, personality change, and the relationships among the three different forms of personality stability. Larsen and Buss review three levels of analysis at which one can consider personality change and stability. Begin by asking students to identify and define each of these three levels (population level, group differences level, individual differences level). Next, distribute Activity Handout 5–2 (“Three Levels of Analysis of Personality Change”). Give students about five minutes to complete the handout. Ask students to volunteer the examples they used for personality change at each of the three levels of analysis. Use this activity as a springboard for discussing the different levels at which one can address personality stability and change. Ask students to consider whether one of the levels of analysis is more important than either or both of the other two. Why or why not? This activity is designed to give students a novel opportunity to consider what personality coherence means. Begin by distributing Activity Handout 5–3 (“Hobbies in Junior High School and Today”). Do not give students any particular instructions. Simply ask them to complete the handout. Give them about five minutes to do this. Next, ask students to volunteer a couple of their favorite hobbies when they were in junior high school and a couple of their favorite hobbies today, encouraging them to identify the personality traits that underlie or are expressed in hobbies that appear rather different at first glance. Next, ask students to consider whether fundamentally different personality traits underlie or are expressed in the hobbies they enjoy today and those they enjoyed in junior high school. Students are likely to comment that there are no such fundamental personality differences. The fact that the hobbies that students enjoy today and the hobbies they enjoyed in junior high school might represent different manifestations of the same personality traits is one expression of personality coherence. Chapter 6 Genetics and Personality Chapter Outline The Human Genome Genome refers to the complete set of genes that an organism possesses Human genome contains 20,000–40,000 genes on 23 pairs of chromosomes Human Genome Project is designed to sequence the entire human genome—i.e., identify the particular sequence of DNA molecules in human species But identifying sequence of DNA molecules does not mean identifying the function of each molecule Most genes in a human genome are the same for all humans Small number of genes are different for different individuals, including genes that indirectly code for physical traits and for personality traits Controversy About Genes and Personality Behavioral geneticists attempt to determine the degree to which individual differences in personality (for example) are caused by genetic and environmental differences Highly controversial Ideological concerns Concerns about renewed interest in eugenics Modern behavioral geneticists who study personality are typically very careful about addressing implications of work and are sensitive to ideological concerns Knowledge is better than ignorance In addition, finding that a personality trait has a genetic component does not mean the environment is powerless to modify the trait Goals of Behavioral Genetics Determine the percentage of individual differences in a trait that can be attributed to genetic differences and the percentage that can be attributed to environmental differences Determine the ways in which genes and environment interact and correlate with each other to produce individual differences Determine precisely where in the “environment” environmental effects exist—e.g., parental socialization, different teachers to which children are exposed What Is Heritability? Overview Proportion of observed variance in group of individuals that can be explained or accounted for by genetic variance, OR Proportion of phenotypic variance that is attributable to genetic variance Environmentality = proportion of observed variance in group of individuals attributable to environmental variance Misconceptions About Heritability Heritability CANNOT be applied to single a individual Heritability is NOT constant or immutable Heritability is NOT a precise statistic Nature-Nurture Debate Clarified No such debate at the individual level Influence of genes and of environment is only relevant for the discussion of group-level variation Behavioral Genetics Methods Selective Breeding—Studies of Humans’ Best Friend Can only occur if a desired trait is heritable Selective breeding studies of dogs Cannot be ethically conducted with humans Family Studies Correlates the degree of genetic relatedness among family members with the degree of similarity in personality trait If a trait is highly heritable, family members with greater genetic relatedness should be more similar to one another on the trait than family members who are less closely genetically related Problem: Members of a family who share the same genes also usually share the same environment—confounds genetic with environmental influences Thus, family studies are never definitive Twin Studies Estimates heritability by gauging whether identical (monozygotic or MZ) twins, who share 100 percent of genes, are more similar than fraternal (dizygotic or DZ) twins, who share only 50 percent of genes If MZ twins are more similar than DZ twins, this provides evidence of heritability Calculating heritability—many formulas, simple one: Two times difference between correlation (“r”) for MZ twins and DZ twins, or 2 (rmz—rdz) Two assumptions of the twins method Equal environments assumption Representativeness assumption Adoption Studies Positive correlations on traits between adopted children and adoptive parents provide evidence of environmental influence Positive correlations between adopted children and genetic parents provide evidence of genetic influence Adoption studies are powerful because they get around the equal environments assumption—genetic and environmental causes are unconfounded Assumption that adopted children and their adoptive and genetic parents are representative of the general population—questionable Problem of selective placement of adopted children Design that combines strengths of twin and adoption studies = twins reared apart Major Findings from Behavioral Genetic Research Personality Traits Summaries of behavioral genetic data yield heritability estimates for major personality traits (extraversion, agreeableness, conscientiousness, neuroticism, openness to experience) of about 20–45 percent Sexual orientation Controversial and developing area Current evidence suggests that genes provide modest and indirect influence (via childhood gender nonconformity) on adult sexual orientation Attitudes and Preferences Wide variance in heritability of attitudes Some attitudes (e.g., traditionalism) show high heritability (about .60), whereas others show low or no heritability (e.g., beliefs in God, attitudes toward racial integration) Not clear why only some attitudes appear to be heritable Drinking and Smoking Behavioral manifestations of personality traits such as sensation seeking, extraversion, neuroticism Drinking alcohol and smoking cigarettes are stable over time Both show evidence of heritability Marriage Heritability estimate for propensity to marry is 68% A genetic proclivity to marry occurs, at least in part, through heritable personality traits that are desired by potential marriage partners Shared Versus Nonshared Environmental Influences: A Riddle Same studies that suggest moderate heritability also provide good evidence of the importance of environmental influences Personality characteristics show heritabilities in 30-50% range; hence, showing substantial degree of environmentality—50-70% Two key types of environmental influences Shared: In family environment, features of the environment shared by siblings (e.g., number of books in home) Nonshared: In family environment, features of the environment that differ across siblings (e.g., different friends, different teachers) For most personality traits, the environment has major influence, but this influence is primarily in the form of nonshared and not shared variables For most personality traits, the shared environment has little impact We do not know which nonshared experiences have a key impact on personality Genes and the Environment Genotype-Environment Interaction Differential response of individuals with different genotypes to the same environments For example, task performance of introverts versus extraverts in loud versus noisy conditions Individual differences interact with environment to affect performance Genotype-Environment Correlation Differential exposure of individuals with different genotypes to different environments Three types of genotype-environment correlations Passive: Parents provide both genes and environment to children, yet children do nothing to obtain that environment Child’s verbal ability and the number of books in home Reactive: Parents (or others) respond to children differently depending on the child’s genotype Baby’s liking for cuddling and the mother’s cuddling behavior Active: Person with particular genotype seeks out a particular environment High sensation seekers expose themselves to risky environments Genotype-environment correlations can be positive or negative Molecular Genetics Techniques designed to identify specific genes associated with personality traits D4DR gene located on the short arm of chromosome 11, codes for dopamine receptor Most frequently examined association between D4DR gene and a personality trait involves “novelty seeking” Individuals with the “long repeat” version of D4DR gene are higher on novelty seeking than individuals with the “short repeat” version of gene But several failures to replicate association and, when replicated, association is weak
Behavior Genetics, Science, Politics, and Values Findings that some personality traits are heritable seemed to violate prevailing environmentalist view that personality is determined by socialization practices, such as parenting style People also worried about political and ideological misuse of behavioral genetics findings Much controversy surrounding individual differences in intelligence In past decade, attitudes shifted somewhat so that behavioral genetics are fairly mainstream (recent exception is sexual orientation studies) Because scientific research can be misused for political and ideological goals, scientists bear special responsibility, but Science can be separate from values Knowledge is better than operating in ignorance SUMMARY AND EVALUATION Most compelling evidence for heritability and environmentality of personality comes from findings generated across methods that do not share the same problems and limitations Personality variables such as extraversion and neuroticism have moderate heritability, as do drinking, smoking attitudes, and sexual orientation These studies suggest that these same variables have moderate to strong environmentality Much of the environmental influence is due to nonshared variables—experiences unique to siblings Genotype-environment interaction and correlations, as well as the new field of molecular behavior genetic analysis, are promising areas for future work KEY WORDS Genome Equal Environments Assumption Genetic Junk Adoption Studies Eugenics Selective Placement Percentage of Variance Gender Identity Disorder (GID) Heritability Shared Environmental Influences Phenotypic Variance Nonshared Environmental Influences Genotypic Variance Genotype-Environment Interaction Environmentality Genotype-Environment Correlation Nature-Nurture Debate Passive Genotype-Environment Correlation Selective Breeding Reactive Genotype-Environment Correlation Family Studies Active Genotype-Environment Correlation Twin Studies Molecular Genetics Monozygotic (MZ) Twins D4DR Gene Dizygotic (DZ) Twins Environmentalistic View Chapter Overview This chapter provides students with an introduction to research and theory at the interface of genetics and personality. The authors begin with a discussion of the human genome, then move to a consideration of the controversy surrounding genetic influences on personality. The authors note that much of this controversy is generated by misinformed political and ideological concerns about the application of the findings from behavioral genetics. The authors review the scholarly goals of modern behavioral geneticists, then provide a definition for key terms such as heritability, environmentality, phenotypic variance, and genotypic variance. Next the authors detail several key misconceptions about heritability, including that it can be applied to a single individual, that it is constant and unchangeable, and that it is precise. The authors then review the four key research designs used by behavioral geneticists, including the selective breeding design, family designs, twin designs, and adoption designs. Each design has advantages and disadvantages, and these are reviewed in turn. Next the authors review the major findings generated from behavior genetics research, including findings in the areas of traditional personality traits, sexual orientation, attitudes and preferences, drinking, and smoking. The authors then discuss and differentiate shared and nonshared environmental influences. Next the authors review work on genotype-environment interaction and correlations and then address recent work in the new area of molecular behavior genetics. The authors close with a discussion of the inter-relationships among science, politics, and values. Learning Objectives Discuss historical and current controversy surrounding the genetic analysis of personality. Discuss why behavioral genetics research is controversial, with reference to issues surrounding ideology conflicts and fears about eugenics. Identify and describe the actual scholarly goal of modern behavioral geneticists. Define and discuss the concept of heritability, with reference to phenotypic variance, genotypic variance, and environmentality. Identify and discuss three key misconceptions about heritability. Discuss the nature-nurture debate, from the perspective of modern behavioral genetics. Identify and discuss the four key research deigns used by behavioral geneticists, including a discussion of the advantages, disadvantages, and assumption of each design. Identify and discuss the major findings from behavioral genetics research, including findings in the areas of personality, sexual orientation, attitudes and preferences, drinking, and smoking. Discuss and differentiate shared environmental influences from nonshared environmental influences. Discuss the impact of shared versus nonshared environmental influences on personality. Define and provide examples of genotype-environment interactions. Define and provide examples for each of the three types of genotype-environment correlation, including passive, reactive, and active correlations. Discuss the emerging field of molecular behavior genetics, including its goals, methods, and recent findings. Discuss why science, politics, and values sometimes seem to be in conflict with respect to behavioral genetic findings. Provide a clear rationale for why behavioral genetics research should continue, and why knowledge is better than operating in ignorance. Lecture Topics and Lecture Suggestions Heritability of Happiness (Lykken & Tellegen, 1996). Students are likely to find a presentation of research documenting the heritability of happiness intensely interesting and controversial. A brief overview of the study can be presented, as provided below. The instructor should plan to spend at least several minutes of class time discussing the results. What do students think of these results? Are they upsetting? Inspiring? What do they mean? Be sure to monitor student comments for a clear and correct understanding of modern behavior genetics. For example, one certainly wrong conclusion based on this research is that happiness is set at birth and there is nothing one can do to change it—that is, happy people will always be happy and unhappy people will always be unhappy. This is not a proper conclusion of this research (and also remind students about the misunderstanding of behavioral genetics presented by Larsen and Buss). Instead, this research indicates that, in the population studied, about 80% of the individual differences in happiness “set-point” are attributable to genetic differences. This means, of course, that about 20% of these individual differences are attributable to environmental differences. Ask students to consider what some of these environmental differences might be. Lykken & Tellegen (1996) measured happiness, or subjective well-being, on a birth-record-based sample of 2,310 middle-aged twins Measured happiness using the Well-Being (WB) scale of the Multidimensional Personality Questionnaire Also measured SES, educational attainment, family income, marital status, and religious commitment None of these variables could account for more than about 3% of the variance in well-being From 44–52% of the variance in well-being, however, is associated with genetic variation Re-tested smaller samples of twins after intervals of 4.5 years and 10 years Authors estimate that heritability of stable component of subjective well-being approaches 80% Reference: Lykken, D., & Tellegen, A. (1996). Happiness is a stochastic phenomenon. Psychological Science, 7, 186–189. Genetic Influence on Risk of Divorce (McGue & Lykken, 1992). Another topic that students are likely to find both interesting and controversial is that of the heritability of divorce. A brief overview of the McGue and Lykken (1992) study can be presented, as provided below. As with the presentation of the heritability of happiness, the instructor should plan to spend at least several minutes of class time discussing the results. What do students think of these results? Are they upsetting? Inspiring? What do they mean? As with the discussion of the heritability of happiness, be sure to monitor student comments for a clear and correct understanding of modern behavior genetics. For example, one certainly wrong conclusion based on this research is that the likelihood that one will divorce is set at birth and there is nothing one can do to change it—that is, your are born either doomed to divorce or destined not to divorce, following marriage. This is not a proper conclusion of this research (and also remind students about the misunderstanding of behavioral genetics presented by Larsen and Buss). Instead, this research indicates that, in the population studied, about 50 percent of the individual differences in risk of divorce are attributable to genetic differences. This means, of course, that about 50 percent of these individual differences are attributable to environmental differences. Ask students to consider what some of these environmental differences might be. McGue and Lykken (1992) explored the separate influence of genetic and environmental factors on risk of divorce They examined divorce status of 1,516 same-sex twin pairs (722 monozygotic [MZ] and 794 dizygotic [DZ]), their parents, and their spouses’ parents Concordance for divorce was significantly higher in MZ than DZ twins The robustness and magnitude of the MZ-DZ difference in divorce concordance indicates a strong influence of genetic factors in the etiology of divorce Moreover, family background of both spouses contributed independently to couples’ divorce risk Latter result suggests that, in many cases, divorce may be largely the result of characteristics the two spouses bring to the union rather than to interaction effects Results also suggest that adjustment difficulties seen with some children of divorced parents may be due to an interaction between genetic and environmental factors rather than environmental influences alone Reference: McGue. M., & Lykken, D. T. (1992). Genetic influence on risk of divorce. Psychological Science, 3, 368–373. Classroom Activities and Demonstrations Larsen and Buss present a simple formula for calculating heritability. One simply takes the difference between the correlation on some trait for monozygotic (MZ) or identical twins and the correlation on that same trait for dizygotic (DZ) or fraternal twins. Distribute Activity Handout 6–1 (“Calculating Heritability from Twin Studies”). Review this formula for students (which appears on the Activity Handout) and give them about 10 minutes to calculate heritability for the three examples. Ask students to volunteer their answers. Work out the examples on the board or on an overhead transparency, so that students who calculated an incorrect heritability can understand what they did wrong. The point of this exercise is not to quiz students on their math skills. Instead, the point is to demystify the calculation of heritability, so that students see that there is nothing magical about these calculations. Once you have established the correct answer for each example, discuss with students what each answer means—namely, the degree to which individual differences in the trait can be attributed to genetic differences or environmental differences. Ask students to tell you why this formula gives you an estimate of heritability. Instructors may also wish to use this activity and the discussion as a springboard for addressing what heritability means and what it does not mean. Larsen and Buss note that there are two key assumptions of the twin method used by behavioral geneticists. If either assumption is not met, then the results from the twin study might be called into question. These assumptions are the equal environments assumption, and the assumption that twins are representative of the general population. Distribute Activity Handout 6–2 (“Assumptions of Twin Studies”). Give students five minutes to describe these assumptions in their own words. Then ask for volunteers to share their responses. Use this activity as a springboard for discussing the twin design of behavioral genetics. Challenge students to identify why these are assumptions of the twin method, and why it is problematic if these assumptions are not met. Finally, close your discussion by noting that recent research suggests that neither of these assumptions is violated in most twin studies of personality. Behavioral geneticists distinguish between two types of environmental influences: Shared environmental influences and nonshared environmental influences. Distribute Activity Handout 6–3 (“Shared and Nonshared Environmental Variables”). Give students about five minutes to complete the handout. Ask students to volunteer their responses and carefully correct incorrect responses. Use this activity as a springboard for discussing the difference between shared and nonshared environmental influences on personality. Ask students to speculate why it is the case that most of the environmental influences on personality have been identified as nonshared, rather than shared environmental influences. Finally, ask students to address why this latter set of findings is controversial among social scientists, particularly among those who argue that parenting and various socialization processes are critical determinants of personality. Instructor Manual for Personality Psychology: Domains of Knowledge About Human Nature Randy Larsen, David Buss 9780078035357