Knowt
EXAM 2
Chapter 6 Traits and Types: The Big Five and Beyond
The Point of Measuring Traits Traits predict behavior Traits can be used to understand behavior What types of behaviors would be important to understand/predict (Spoiler alert: it depends)
Research Methods Used to Connect Traits with Behavior • Single-trait approach • Many-trait approach • Essential-trait approach • Typological approach
The Single-Trait Approach • What do people with a certain personality trait do? – “What do people like that do?” • Examine correlations between one trait and many behaviors
The Single-Trait Approach • Self-monitoring – It’s not necessarily better to be high or low – Actors scored high and mental patients scored low – Correlates with several behaviors • You can see where you fit!
Where do you fit?
I find it hard to imitate the behavior of other people. T/F
At parties and social gatherings, I do not attempt to do or say things that others will like T/F
I can only argue for ideas I already believe in T/F
I can make impromptu speeches even on topics about which I have almost no information T/F
The Single-Trait Approach • Narcissism – Charming, make good first impression – Manipulative, overbearing, vain, and so on – Many negative behaviors and attributes • Aggression, argumentative, – Why do they act like this? – Not all of narcissism is bad…nor is it disordered
Food for thought • Narcissism & Leadership – (I’ll make the chapter available to inspire Yellowdig posts)
The Many-Trait Approach • Who does that important behavior? – Examine correlations between one behavior and many traits • California Q-Set – 100 personality descriptions – Sort into a forced choice, symmetrical, and normal distribution – Compare characteristics within an individual
The Many-Trait Approach • Word use – Certainty words: related to being perceived as intelligent, verbally fluent, turned to for advice, ambitious, generous
The Many-Trait Approach • Political orientation – Conservative: favor values of in-group loyalty, authority and respect, and purity; and less able to handle stress well as children – Liberal: favor values of reduction of harm & fairness; independent & confident as children – Authoritarian: strongest in value of respect for authority/prefer strong leaders, uncooperative and inflexible, likely to obey a command to harm others, fewer positive emotions
The Essential-Trait Approach • Which traits are the most important? Which traits really matter? • Theoretical approaches to reducing the many to a few – Murray: 20 needs – Block: ego-control and ego-resiliency
The Essential-Trait Approach • Factor analytic approaches to reducing the many to a few – Cattell: 16 essential traits – Eysenck: extraversion, neuroticism, psychoticism – Tellegen: positive emotionality, negative emotionality, constraint
The Essential-Trait Approach: The Big Five and Beyond • Discovery of the Big Five – Factor analysis – Other personality tests tend to fit the Big Five groups • Lexical hypothesis – Look for traits that have the most words and are the most universal
The Essential-Trait Approach: The Big Five and Beyond • Implications of the Big Five – Can bring order to many research findings – Traits are (theoretically) orthogonal, or unrelated – More complex than they seem at first • Not entirely orthogonal (independent) • Higher-order factors: stability and plasticity – More stable: Agreeableness, Conscientiousness, & (Low) Neuroticism – More plastic: Extraversion & Openness • Lower-order factors or facets
The Essential-Trait Approach: The Big Five and Beyond • Universality of the Big Five – When translated to other languages, four or five of the factors appear • Support – Lexical Hypothesis – When starting with other languages: some overlap but not one-to-one correspondence – Scores vary by geographic region
The Essential-Trait Approach: The Big Five and Beyond • Beyond the Big Five (criticisms) – There is more to personality – Too broad for conceptual understanding • Doesn’t give us information about the “type” of person someone is Typological Approach to Personality • Based on doubt about whether it is valid to compare people quantitatively on the same trait dimensions – Important differences between people may be qualitative • Challenges: find divisions that distinguish different types; show differences are qualitative
Examples • Empirical – Myers-Briggs Type Indicator – Poor validity • Muhammad Ali’s Implicit Theory – Personalities as fruits: – Poor Validity
Typological Approach: The MyersBriggs Type Indicator (1) • Used in workplaces, schools, counseling centers, management workshops, etc. • A big business • Four opposing tendencies: o Extroversion (E) vs. Introversion (I) o Sensing (S) vs. Intuition (N) o Thinking (T) vs. Feeling (F) o Judgment (J) vs. Perception (P) • 16 possible personality types
Typological Approach: The MyersBriggs Type Indicator (2) • Reasons for popularity – Offers seemingly rich and intriguing descriptions of each personality type – Looks insightful – All types are explained positively. – People think learning their type is enjoyable
Typological Approach: The MyersBriggs Type Indicator (3) • Criticisms – Not useful for selection or predicting life outcomes – Based on normally distributed scores – Measurement is not reliable – No evidence that different types follow, persist in, or succeed in different lines of work
Myers-Briggs VS Horoscope
Typological Approach to Personality • Three replicable types – Well adjusted – Maladjusted overcontrolling – Maladjusted undercontrolling • But types do not predict behavior beyond what can be predicted with traditional trait Scores
Recent research on Types • A typological approach…rooted in the Big 5 – Gerlach, Farb, Revelle, Nunes, & Amaral (2018) • Washington Post Article • Four types of people – Reserved – Role Model – Self-Centered – “Average”
Typological Approach to Personality • Is it useful to think about people in terms of types? – Yes (maybe) – Summary of standing on several traits – Makes it easier to think about how traits within a person interact with each other – But doesn’t add up to ability to predict outcomes • (as of now)
Can personality predict behavior over a lifespan?
Chapter 7 Personality Stability, Development, and Change
Think carefully… How have you changed over the last 5 years? How have you stayed the same? How do you think you might change in the future?
What is our reference point? Are we evaluating our personality as an individual? Or are we evaluating our personalities against our peers? Rank-order consistency: the maintenance of individual differences in behavior or personality over time or across situations But what does this actually mean?
Two Types of Continuity – Caspi 1998 Absolute Continuity “When taking the MBTI (MyersBriggs Type Indicator), Dr. Ed scores high in Extraversion” Differential Continuity -Dr. Ed was extraverted when he in college, and he is extraverted Now This continuity is relative to peers ▪ This can still change over time when examining only the individual
Interpreting Correlations Survey 100 people when they are age 18 & 28 Ex: Extraversion at 18 correlates with extraversion at 28 r = .80, p < .001 Absolute or differential continuity? Strong DIFFERENTIAL continuity
Absolute vs. Differential Continuity Take our example Strong correlation, but Extraversion still might have gone DOWN on average Strong Diff-Cont Weaker Abs-Cont 2007 2017 Person1 10 7 Person2 8 5 Person 3 9 6 Person4 6 3 Person5 5 2 Person6 4 1 Average: 7.0 4.0
Differential Continuity Absolute continuity isn’t measured as often We tend to compare differences among people who are the same age AKA: heterotypic continuity Continuity in behaviors varies with age Ex: shy adults do not hide behind their parents when meeting new people, but shy children do
Personalities do change over time Some traits are more consistent than others Conscientiousness Neuroticism ▪ Gradual decrease Openness ▪ Gradual increase Extraversion ▪ Decrease early in life
Personality Changes Across Cohorts Women’s assertiveness depends greatly on when they were born Twenge (2000, 2001) Narcissism & Anxiety – we’ve discussed this Twenge (2000, 2008)
Overall High differential continuity throughout adulthood In general, the larger the gap, the lower the continuity Ex: Neuroticism ▪ 6 year gap – r = .83 (Costa & McCrae, 1988) ▪ 10 year gap – r = .67 (Costa & McCrae, 1978) ▪ 16 year gap – r = .66 (Helson & Moane, 1987) ▪ 18 year gap – r = .46 (Conley, 1985) ▪ 30 year gap – r = .56 (Finn, 1986)
When is the earliest we can learn about a person’s personality?
Temperament = early-appearing, stable individual differences in reactivity & self regulation Reactivity - quickness & intensity of emotional arousal, attention, and motor action Self-regulation – strategies that modify reactivity
Cornerstone of personality Thomas & Chess’ New York Longitudinal Study (1956) First influential model Followed 141 children from early infancy into adulthood Impacts psychological adjustment Increase chances of psych problems OR Protect from neg effects of stress Parenting practices
Structure of Temperament Easy – 40% Adapts easily, cheerful Difficult – 10% Slow to accept new experiences, neg & intense reactions Future risk Slow-to-warm-up – 15% Adjusts slowly to new experiences, inactive & fearful Unclassified – 35%
Temperament and Modern Perspectives We’re no longer as likely to group children into categories Between-person approach Now, researchers analyze children on various temperament dimensions Within-person approach Dr. Mary Rothbart University of Oregon
Rothbart & Bates’ (2006) – 3 dimensions Extraversion/surgency Positive anticipation, impulsivity, activity level, sensation seeking Negative affectivity Fear, frustration, sadness, discomfort Effortful control (self-regulation) Attentional focusing/shifting, inhibitory control, perceptual sensitivity, low intensity pleasure
BASED ON Rothbart et al., 2001; Gartsein & Rothbart, 2003, Rothbart et al., 2004 Sample items for Infants and Children “How often during the last week did the baby startle to a sudden or loud noise?” “My child is not afraid of large dogs and/or other animals.” “When put into the bath water, how often did the baby splash or kick? “My child seems always in a big hurry to get from one place to another.” Stability of Temperaments During Infancy 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 of Temperament during childhood Develops with age Overall, low to moderate stability Better after age 3 ▪ Emotion, attention, and action better established ▪ Brain development – frontal lobes
Effects of Temperament on One’s Environment Selection People choose situations that match their personality Manipulation People change situations to be congruent with their personality Evocation Personality differences evoke different reactions from others
Shared vs Nonshared Environmental Influences - SIBLINGS Shared: Features shared by siblings Parental Values Socio-Economic Status (SES) Nonshared: Features that differ for siblings Friends and teachers Activities and hobbies Birth order
Types of Unique Sibling Experiences Random Experiences that occur outside of the family: School, Peers, Athletics, Hobbies, etc. Systematic Influences related to one’s ordinal position (i.e., birth order) within the family. Relative Age Power (physical, intellectual, etc.) Privilege within the Family Family Size
Influences on IQ Shared Environment MATTERS Correlation among adoptive siblings is .32 Non shared influences Birth order
Historical note: Adler’s Views on Birth Order Siblings compete for parental resources Attention, affection, etc. 1st born child is “dethroned” by later siblings Cope by emulating parents Over emphasize rules and order Become “power hungry conservatives”
Correlations Related to Birth Order and IQ 1st born children Talk earlier and more clearly Learn to read earlier Perform better on problem solving tasks Higher achievers in school Score higher on IQ tests IQ study of 400,000 Danish children IQ declines with birth order IQ declines with family size
Birth Order and IQ Possible Explanations Differential parental treatment Parents have less experience/greater expectations for 1st born children More time spent on intellectual tasks Quality of intellectual environment Later born / children from larger families spend more time interacting with kids Older children act as teachers Mutual benefit to the teacher and the learner A few findings related to birth-order Younger siblings tend to show higher levels of openness, agreeableness, and extraversion Older siblings tend to show higher conscientiousness Sulloway, 2010
Adler wasn’t all wrong: “Later born children must compete with 1st born children” Face size/developmental differences Must become more cooperative
Adolescent Egocentrism: The Personal Fable (Elkind, 1981) Characteristic of adolescent thinking that leads young people to focus on themselves to the exclusion of others. Young person might believe his or her thoughts, feelings, and experiences are unique. Ex: “You can’t possibly understand how I feel, MOM! This is different!!” But this script is a rough draft
Types of Scripts Commitment scripts Long-term investment towards improvement Think of a positive scene from your childhood A vision/ideal of what “could be” Absence of conflict – overconfidence? Nuclear scripts “Sh*t gets real” Complex Avoidance/approach conflicts
Sometimes, these scripts/scenes inspire change in our personalities Desire for change is typical, and usually in the socially desirable direction Neuroticism is what people wanted to change the most Agreeableness is what people wanted to change the least Ex: Extraversion 2 = much more 1 = more 0 = the same -1 = less -2 = much less Try for yourself on p.239 Hudson & Roberts, 201 Let’s no
Let’s not forget about the introverts in the room! Introversion has gotten a lot of attention the last decade or so Can be a strength in ways many people underestimate Susan Cain – TED Talk Alternate version of I/E trait test Quiet Revolution
Let’s look at a couple items I don’t take risks unless I’ve done some careful research or evaluation first. A. Very uncharacteristic or untrue, strongly disagree B. Uncharacteristic C. Neutral D. Characteristic E. Very characteristic or true, strongly agree I quickly feel drained when in a large crowd of people. A. Very uncharacteristic or untrue, strongly disagree B. Uncharacteristic C. Neutral D. Characteristic E. Very characteristic or true, strongly agree
4 Potential Methods for Changing Personality Psychotherapy and psychiatric drugs General interventions Targeted (specific) interventions Behaviors and life experiences
Personality Change Psychotherapy and psychiatric drugs Why would this be necessary? General interventions: usually aimed at important outcomes
Personality Change Targeted interventions: addressing specific personality traits/behaviors Increasing self-control: relaxation, learning to think differently about temptations and frustrations, mindfulness meditation, set realistic goals that are compatible with personal values
Personality Change Behaviors and life experiences Positive: exercise, starting college or a job, beginning a serious relationship Negative: trying drugs, onset of chronic disease Becoming unemployed Negative life events Travel Military training
Personality Change Obstacles to change Not seeing a reason for change Takes effort Blaming negative experiences and failures on external forces People like consistency and predictability
If you DO want to change Who do you want to be? How is that person different from the one you are now? What can you do (TODAY) to make this change start to happen?
Chapter 8-The Anatomy and Physiology of Personality LET’S START WITH A CASE STUDY • Does anyone in class recognize the name Charles Whitman? • What about now? • On August 1, 1966, Charles Whitman climbed to the top of a tower on the campus at UT-Austin and began shooting • One of the earliest, deadliest massshootings in American history • Also killed his wife and mother • “After my death I wish that an autopsy would be performed on me … I cannot rationally pinpoint any specific reason for doing this” – Charles Whitman, the day before the shooting
THEY FOUND A TUMOR • Located near the amygdala… • More questions than answers • Assuming that the tumor was affecting his brain functioning, was Whitman aware of desires to kill? • Was he in control of the desires? • Had Whitman been captured and not killed, and you were on a jury trying him, would you have found him guilty or not guilty? • Of course, this is not the only case study we know that indicates brain structure is related to personality
BRAIN DAMAGE - PHINEAS GAGE • Railroad worker injured by misuse of gunpowder • Rod went through frontal lobe • Attitude changed • Pre-accident: Hard-working, responsible and popular • Post-accident: Impatient, stubborn, vulgar and spontaneous.
HOW DO WE KNOW WHAT THE BRAIN IS DOING?
Dissection (post mortem examination of brain structures) • Ex: Whitman
Study brain damage • Ex: Gage
Activating the brain
Monitoring the brain in action
I COULD SHOW YOU A RELATIVELY GROSS VIDEO HERE…BUT I’M NOT • Electrical stimuli can activate neuron firing when applied to specific parts of the brain • Fortunately, we have other approaches
• Transcranial magnetic stimulation (TMS
TECHNIQUES FOR MONITORING THE BRAIN IN ACTION • Electroencephalograph (EEG) • Computerized Tomography Scan (CT Scan) • Positron Emission Tomography (PET) • Magnetic Resonance Imaging (MRI) • Functional Magnetic Resonance Imaging (fMRI) • Neurotransmitters
ELECTROENCEPHALOGRAPH (EEG) • Measures gross electrical activity of brain • Reports brain waves during activities (like sleeping)
COMPUTERIZED TOMOGRAPHY SCAN (CT SCAN) • Like an x-ray of the brain • Used to detect tumors or injuries
POSITRON EMISSION TOMOGRAPHY (PET) • Patient ingests harmless radioactive substance (a sugar!) that travels to the brain • Areas of the brain that are working will absorb more of this substance and “light up”
MAGNETIC RESONANCE IMAGING (MRI) • Uses magnets to look at the structure of the brain. • Produces 3-D pictures of the brain that are extremely detailed
FUNCTIONAL MAGNETIC RESONANCE IMAGING (FMRI) • Also creates a detailed 3-D image on the brain • Measures oxygen in blood in the brain to determine activity
MRI VS FMRI
MRI studies Brain Anatomy fMRI studies Braid Function
PROCEED WITH CAUTION • What happens in the brain when you show a subject emotional vs. non-emotional scenes? • What if the subject is a salmon? • A salmon that happens to be dead? • Brain activity! • Bennet, et al. (2010)
THE ANATOMY OF PERSONALITY: RESEARCH METHODS FOR STUDYING THE BRAIN • Difficulties with imaging techniques • May indicate inhibitory activity • All parts of the brain are always active to some degree • Blood oxygenation level dependent (BOLD) imaging signals and perfusion imaging • Brain activity in response to a stimulus does not mean the same psychological process occurs every time that area is active
HIGH SS VS LOW SS BRAINS • Remember when we said that people high in extraversion were less responsive to punishment in gambling? • Here, we see the same pattern in High vs. Low Sensation Seekers • Both High SS’s and Low SS’s participants respond to rewards (“Win”) • More activation after punishment (“No Win”) in the brains of High SS’s * than in the brains of Low SS’s **
SENSATION SEEKING – REVIEW • “The need for varied, novel, and complex sensations and experiences and the willingness to take physical and social risks for the sake of such experiences” (Zuckerman, 1979, p. 10) • Can you describe it in your own words?
NEUROPSYCHOLOGY OF SENSATION SEEKING • Monoamine oxidase (MAO) – enzyme that helps regulate the level of neurotransmitters in the body by breaking down the NTs • Sensation seekers tend to have low levels of MAO in their bloodstream • Which NTs might be more prevalent for sensation seekers? • Dopamine • Epinephrine/norepinephrine
BIOCHEMISTRY AND PERSONALITY: NEUROTRANSMITTERS • Dopamine • Possible relation with bipolar disorder, extraversion, and impulsivity • Individual differences in development of nerve cells that produce and are responsive to dopamine • Activates the behavioral activation system (BAS)
BAS/BIS DISTINCTION • Behavioral Activation System (Gray 1982, 1987) vs. Behavioral Inhibition System (Gray, 1987) • Approach vs. Avoidance • Which “Big 5” trait do you think is more associated with BIS? • NEUROTOCISM
TWO ASPECTS OF THE BRAIN THAT CAN BE EXAMINED WITH TECHNOLOGY • Anatomy: functions of parts of the brain • Biochemistry: effects of neurotransmitters and hormones on brain processes • Both are related to personality and behavior • Both have been used to TREAT abnormal psychology as well
THE ANATOMY OF PERSONALITY: THE LESSONS OF PSYCHOSURGERY • Prefrontal leucotomy (by 1937) • Prefrontal lobotomy—more drastic • Observations of patients consistent with brain damage • Replaced with drugs • Is this better?
TED TALK • Sometimes, we don’t know why a treatment works
AN ALTERNATE APPROACH • Amazingly, deep transcranial magnetic stimulation has ALSO shown tremendous promise for people suffering from severe depression!
UPDATE! • FDA Clears SAINT Rapid-Acting Brain Stimulation Approach fo r Those Suffering From Resista nt Major Depression • This approval only happened on September 6th, 2022 • Very exciting to see what happens next!
THE BIOCHEMISTRY OF PERSONALITY • Galen (Rome, A.D. 130–200) proposed that personality depended on the balance of humors (blood, black bile, yellow bile, phlegm) • The chemistry of the mind • Neurons communicate with neurotransmitters • Hormones stimulate or inhibit neural activity • About 60 chemicals transmit information in the brain and body • People differ in average levels
THE BIOCHEMISTRY OF PERSONALITY: NEUROTRANSMITTERS • Dopamine • Involved in responding to reward and approaching attractive objects and people • Related to sociability, general activity level, and novelty seeking • Parkinson’s disease • Serotonin • Depression
THE BIOCHEMISTRY OF PERSONALITY: SEROTONIN (AND PROZAC) • Prozac: a selective serotonin reuptake inhibitor (SSRI) • Physical effect: increases serotonin levels • Changes in personality for people without a diagnosed disorder • Makes negative emotions less severe and doesn’t affect positive emotions
THE BIOCHEMISTRY OF PERSONALITY: HORMONES • Testosterone • Concentration in men is about 10 times higher than in women • Link with aggression is complex • Role in control and inhibition of aggression and sexuality • Related to many other behaviors • Unknown causal direction
THE BIOCHEMISTRY OF PERSONALITY: HORMONES • Cortisol • Released in response to stress • Chronically high levels in people with severe stress, anxiety, and depression • Low levels related to post-traumatic stress disorder (PTSD) and sensation seeking
THE BIOCHEMISTRY OF PERSONALITY: HORMONES • Oxytocin • Role in mother-child bonding, romantic attachment, and sexual response • Decreases fearfulness • Facilitates approach behaviors
THE BIG FIVE AND THE BRAIN • Relationships between personality, brain anatomy, neurotransmitters, and hormones are complex • Ex: Stability is associated with serotonin and plasticity is associated with dopamine • Figure 8.14, p.304 • but you don’t need to memorize these
BIOLOGY: CAUSE AND EFFECT • “The relationship between the brain and its environment works in both directions” (p. 298) • Understanding the brain can help us understand behavior, but understanding behavior can also help us understand the brain • Remember how sensation seekers are likely to have less MAO? • Serial killers also show differences in the related MAOA gene, But they must experience trauma for the gene to be activated • Ted Talk – Exploring the Mind of a Killer, Jim Fallon
Chapter 9 Genetics and Evolution: The Inheritance of Personality Understanding human nature Why do people act the way they do? What motivates someone to act the way they do? How have we evolved to think and behave the way we do? – Evolutionary psychology
Genes, Behavior, & Evolution We’ll get to genes soon… Evolutionary Psychology – the study of the evolution of cognition and behavior using principles of natural selection Who can give a good definition of what natural selection is?
Charles Darwin - Natural selection Natural selection: – The process whereby nature gradually selects those characteristics of organisms that promote survival and reproductive success
Classic Example: Physical Characteristics Long-necked (LN) giraffes Short-necked (SN) giraffes Who could reach more leaves on the trees? – LN giraffes LN giraffes were more likely to survive (more food) – Offspring with long-necks
Relatable Example: Halloween Candy Imagine I have a giant bowl of candy (alas, I do not) Which traits or characteristics will you look for in the candy you select – Desirable candy More likely to be selected/ pass on genes – Undesirable candy Dies childless and alone…
So how can we tell if something is an evolutionary adaptation? Difficult to test empirically! Some will be specific to individual cultures/species The most basic (and potentially most important) behaviors/traits should show up cross-culturally – Let’s evaluate some evolutionary hypotheses
Read my lips The “Universality” of emotions? – Happiness (A) – Sadness (B) – Surprise – Fear – Disgust (C) – Anger – Contempt* Why would this be beneficial?
Emotions & Survival The anger superiority effect – We recognize ANGER faster than any of the other emotions Specific ways recognizing emotions can be adaptive – Preparation for action – fight or flight? – Is this person someone I can trust? Babies also attend more to smiling (safe) Faces
How good are you at recognizing emotions? 16-year-old participants misidentify this emotion 75% of the time
Some of you did better than others Implications for survival – Ex: Lie detection, safety, etc. Fortunately, you all have lots of OTHER attributes that contribute to your inclusive fitness “An organism’s overall (total, inclusive) ability to maximize the replication of the genes that designed it” McAdams, 2009, p. 35
Conclusions? So, does this mean that facial expressions/emotions are universal/evolutionary adaptations? – Spoiler alert: IT DEPENDS – Context matters
Example 2: Why do we help each other? From an evolutionary standpoint, why would altruism occur? – Kin selection – family first! – Helping others (outside of our family tree) will not help us survive or help pass on our genes Does “true altruism” exist? – Many psychologists say NO – What do you get in return?
West, Whitney, & Schnedler, 1975 Researchers posed as motorists in distress trying to flag passing cars to provide help with a flat tire – Cars were MUCH more likely to stop for a woman than for a man – Most of the cars that stopped were driven by young men who were driving alone
Feeling good about ourselves… and feelings in general Besides sexual motives, we will often help others to change or maintain our positive mood – Helping others can make us feel good in return Can anyone think of other factors that might make a person more/less likely to help someone? – Personality – Culture – Others
Reasons for helping They will help you someday You want to feel good about yourself You want other people to think you are a good person ALL OF THESE INCLUDE SOCIAL EXCHANGE
What do we get back? Reciprocal Altruism – Trivers (1971) Early hunter/gatherer societies – Sharing resources with hopes of receiving help at another time – Mutual benefit to be helpful to nonrelative others
Moving on… To understand why individuals act the way they do, you must first understand human nature and evolutionary psychology – Plenty of other traits/behaviors E.g. Aggression – Cross-cultural evidence is key We cannot forget about genes
Genetics 99% of all human genes are identical – 98% shared with chimpanzees (Balter, 2002) How can we differentiate between effects related to Nature vs. Nurture?
Twins are studied here at FSU The Florida State Twin Registry – Established in 2002/03 by Dr. Jeanette Taylor (previous department chair) Other collaborators in the dept: – Dr. Chris Schatschneider – Dr. Richard Wagner – Dr. Sara Hart So, why are twins so important?
Identical vs. Fraternal Twins Monozygotic (MZ) versus dizygotic (DZ) twins – In other words, ONE or TWO zygotes
Heritability quotient Difference between correlation (r) for MZ and DZ twins (rMZ – rDZ) x 2
Calculating Heritability Heritability coefficients from twin studies ≈ .40 Heritability coefficients from nontwin studies ≈ .20 Difference suggests that the effects of genes are interactive and multiplicative
Behavior Genetics Many traits/behaviors have genetic links, but environment (pre- AND post-natal) matters
Environment-gene interactions Epigenetics: experience affects biology – May be possible to help people find environments that will lead to good outcomes “How your genes shape who you are” - BBC Want to learn more about it? – “Lick your rats” lab website Anxiety can be genetic, but rat pups that were nurtured (aka: licked/ cleaned) by their mothers grew up to be more calm & less anxious Weaver, et al., 2004
Individuals can also change their environment Evocative person-environment transaction (p-et) – Likely to create/experience hostile environments Reactive p-et – Less likely to create their environment than to react to it Active p-et – Selecting/creating compatible environments
Behavioral Genetics The future – Genes have important influences on personality – Researchers are working to find out which genes are dependably associated with personality – The big picture will be complicated Inheritance is the beginning…not the end
