9 - Biological Bases of Personality Flashcards
What are the biological aspects of the past theories?
- Freud = development of the id, partly development of the ego
- Jung = collective unconscious
- Maslow = instinctoid motivation
- Rogers = actualizing tendency and organismic valuing process
- trait = mostly genetics
What are the factors involved in personality?
- genetics
- shared environmental factors
- non-shared environmental factors
What are shared environment factors?
- variables that people in various situations share
- makes people more similar to each other
- eg. family environment, school environments, broad-scale cultural conditions
What are non-shared environment factors
- all the experiences unique to the individual
- significantly more important in determining the nature of personality
- eg. differential treatment by parents, different interactions with siblings, birth order, sibling age spacing, gender differences, different school experiences, different friends, different hobbies
What are phenotypes and genotypes?
- genotype = specific collection of genes inherited from parents
- phenotype = totality of visible or measurable characteristics
- eg. hair color, eye color, IQ, personality
What are monozygotic and dizygotic twins?
- monozygotic (identical twins) = 100% same genetic base pairs
- develop from a single fertilized egg
- dizygotic (fraternal twins) = 50% same genetic base pairs
- develop from two simultaneously fertilized eggs, no more similar than any pair of siblings
What are the different types of twin studies?
MZ raised together, and MZ raised apart
- assuming 100% genetic determination
- correlation between MZ apart and MZ together should be 1.00
MZ and DZ twins (both raised apart, or both raised together)
- assuming 100% genetic determination
- MZ = 1.00 correlation
- DZ = 0.50 correlation
MZ apart with MZ together, and DZ apart with DZ together
- assuming 100% genetic determination
- 1.00 correlation for MZ (together or apart)
- 0.50 correlation for DZ (together or apart)
What are family studies?
- compare the similarity of people with different degrees of genetic similarity
- siblings = 0.50
- parents = 0.50
- uncles/aunts = 0.25
- grandparents = 0.25
What are adoption studies?
- we can compare the phenotypic similarity of children with their adoptive parents, and (for the same or other children) with their biological parents
- assuming 100% genetic determination
- 0.00 correlation for adoptive parents
- 0.50 correlation for biological parents
What are the problems with twin studies?
- DZ twins confused as MZ
- selective placement
- differences in environmental stability
- assortative mating
What happens when DZ twins are confused as MZ?
- this dilutes the MZ sample
- underestimate the importance of genetics
What is selective placement?
- when comparing together vs. apart, environments should be uncorrelated
- however, there is usually overlap in environments as adoption agency try to find a place similar to where they were born
- overestimate the contribution of genetics
What are the differences in environmental similarity for MZ and DZ twins?
- tendency to emphasize the similarity of MZ twins (assimilation effect)
- tendency to emphasize the differences of DZ twins (contrast effect)
- overestimate the contribution of genetics
What is assortative mating?
- greater parent-child similarity
- tendency to select mate with similar phenotypic preferences (eg. IQ)
- so, individuals with like characteristics tend to marry and have kids
- overestimates the contribution of genetics
How does assortative mating differ from random mating?
Random mating
- no genes in common between parents
- the genes that the child receives from Mom and Dad have no overlap
- 50% from Mom, 50% from Dad
Assortative mating
- parents share some genes in common
- this makes the child more similar to one parent
- eg. 50% from Dad, >80% from Mom
What is variance?
- measure of the variability of scores around the mean score
- VT = VG + VE
- VT = total variance
- VG = variance due to genetic differences
- VE = variance due to differences in the environments
What is the heritability coefficient?
- the proportion of variance in some characteristic or ability that is produced by genetic rather than environmental factors
- h2=VG/VT
What are the different formulae for the heritability coefficient?
- h2 = r (mza)
- h2 = 2r (dza)
- h2 = 2(r (mz) - r (dz))
What are the characteristics of the heritability coefficient?
- applies only to groups, not individuals = how much of total variability is attributed to genetic variability within the sample
- varies from population to population, and over time
- eg. the heritability coefficient is higher now than in the 1800s as the sources of environmental factors are reduced
- valid only if measures used to calculate it are valid
What is temperament?
- something that shapes general behavioural tendencies
- activity level, emotional responsiveness, social interactions with others
- assumed to have a biological basis
What dimensions did Thomas, Chess, and Birch measure?
- level of motor activity = how often they perform an activity
- positive response to new object
- regularity in biological functions
- friendliness or good mood
- adapts to changes in environment = those with autism tend to have a low tolerance for novelty in their routine and environment
- usual degree of energy in responding = separate from motor activity, how they perform the activity
What are easy infants?
- similar to stable extrovert
- regular rhythms
- good mood
- accepts novelty
- adapts well to change
- low to moderate levels of energy
What are difficult infants?
- similar to neurotic introvert
- irregular rhythms
- poor mood
- dislikes novelty
adapts poorly to change - high levels of energy
What happened in Thomas, Chess, and Birch’s 10-year follow up?
- children tended to exhibit the same level of positive and negative responses
- children that required psychological intervention in school = 70% of difficult children, 20% of easy children
- difficult infants are more common in the clinical population
- premature infants are at risk for a difficult temperament
- with increased maternal responsiveness, more children tended to change from difficult to easy
What was Plomin and Rowe’s study?
- studied MZ and DZ twins for their similarity in aspects of sociability
- includes = looking at a stranger, approaching stranger, nearness to stranger, vocalizing to stranger
- contrast effects
- DZ correlations are much smaller than they should be
What was Buss and Plomin’s study?
- developed a 20-item EAS survey to evaluate children on three important dimensions of temperament
- E = emotionality
- A = activity
- S = sociability
- their survey found high heritability coefficients for MZ, but was once again complicated by the contrast effect
What is non-additive variance?
- effects on our phenotype that depends on interactions between genes
- elements = dominant-recessive effects, epistatic effects
What are dominant-recessive effects?
- same locus
- relationship between the two different alleles of a single gene
- although they are 50% similar in respect to eye colour genes, their eye colour with have 0% similarity, as brown is dominant
What are epistatic effects?
- other loci
- effects in which the expression of one gene is affected by a gene is some other location
- interactive effect, as the activity depends on the activity of another gene
What are the problems with non-additive variance?
- MZ twins share 100% of both additive and non-additive gene effects
- however, DZ twins share 50% of additive effects, but only 25% of non-additive effects
- the formula assumes only the existence of additive genetic variance
What are epigenetic effects?
- the placement and removal of markers can be influenced by experiences
- changes the activity of genes
- can be inherited through at least three generations
- part of the epigenome is a methyl group, so the epigenome goes through the process of methylation to shut off a gene
- epigenetics also differentiate cell types in organs
- since siblings and twins don’t experience life the same way, their epigenomes will be different
What is behavioural inhibition?
- high risk for decreased performance school, and increased dropout rates
What were the results of the behavioural inhibition study?
- inhibited = show fear in most situations (10%)
- uninhibited = show no fear in any situation (20%)
- middling = show mixed reactions (70%)
What are the behavioural differences in inhibited children?
- slow to start conversation with unfamiliar adult or peer
- seldom smile spontaneously with unfamiliar other
- slow to relax in unfamiliar situations
- memory impaired following stress
- cautious decision makers
- unusual fears or phobias
What are the physiological differences in inhibited children?
- HR up during stress, or when standing up
- diastolic BP up when standing up
- pupillary dilation under stress
- higher muscle tension
- higher right frontal cortex activation = related with emotional activity (fear, anxiety, concern, worry)
- more allergies
- more activities in HPA axis, RAS, ANS = similar to introverted neuroticism
How is inhibition related to somatotype?
- 60% of inhibited children have blue eyes
- 60% of uninhibited children have brown eyes
- more kin of inhibited children have blue eyes; of uninhibited have brown
- inhibited boys have narrow faces, thin builds
How can you predict inhibition?
- low reactive = low distress, low motor
- increased likelihood to be uninhibited
- high reactive = high distress, high motor
- increased likelihood to be inhibited
- aroused = low distress, high motor
- distressed = high distress, low motor
What was the Loehlin and Nichols study?
- studied correlations between DZ and MZ twins
- they filled out personality and interest tests
- parents completed questionnaires
- males = high heritability coefficients, large contrast effect
- females = low heritability coefficients, no/low contrast effect
What did Tellegan study?
found an average heritability coefficient for personality variables of about 50%
What did Scarr study?
- compared groups of families
- measured introversion, sociability, impulsivity, emotionality, and anxiety
- heritability estimates (siblings) = 0.26
- heritability estimates (parent-child) = 0.22
- heritability decreases ages 55 and up
What is SATSA?
- Swedish Adoption/Twins Study on Aging
- examined middle-aged twins
- calculated heritability using a number of different formulae
- conclusion = we are overestimating the heritability coefficient
- should be closer to 0.25 and 0.30
- 29% genetics
- 9% shared environment
- 62% non-shared environment and error
What are the different research methods for studying the brain?
- brain damage
- brain stimulation = stimulation with electrodes, TMS
- brain activity and imaging = EEG, MEG, PET, fMRI, DTI, MRS
- neural context = studies don’t show which other areas may be active at the same time
What is the amygdala?
- links perceptions and thoughts with their emotional meaning
- anger, fear, social attraction, sexual responsiveness, motivation
- personality traits related to the insula and anterior cingulate = chronic anxiety, fearfulness, sociability, sexuality
- however, to experience the emotions, other brain structures may be necessary
What is the frontal lobe?
- left frontal lobe = approach something pleasant, associated with emotional stability
- right frontal lobe = withdraw from something unpleasant or frightening, associated with neuroticism
What are the stories of Phineas Gage and Elliott?
- Phineas Gage = inability to understand emotions of others and appropriately regulate impulses and feelings
- Elliott = somatic marker hypothesis
- emotions enable people to make decisions to maximize good outcomes and minimize bad outcomes, and to focus on what’s important
How are cognition and emotion related?
- Capgras = fail to feel any emotional response to facial recognition
- emotional experience is an important part of thinking
What is the anterior cingulate?
- important for the experience of normal emotion
- projects inhibitory circuits into the amygdala
- controls emotional responses and impulsive behaviour
- when it is chronically overactive, one result may be neuroticism
What are brain systems?
- systems or circuits may be more important than discrete areas
- parts of the brain work together and constantly interact
What is the biochemistry of personality?
- central nervous system = norepinephrine, dopamine, oxytocin
- peripheral nervous system = epinephrine, oxytocin
- gut = serotonin
What is dopamine?
- traits = sociability, activity, extraversion, impulsivity, plasticity
- lack of dopamine is the basis of Parkinson’s disease
- behavioural activation system (dopamine and nucleus accumbens) = produces and reinforces motivation to seek rewards
What is serotonin?
- inhibition in behavioural impulses
- Prozac = selective serotonin reuptake inhibitor
- more extraverted, lower neuroticism, happier
- antineurotics = make negative emotions less severe while leaving positive emotions unaffected
What is epinephrine and norepinephrine?
- fight-or-flight response
- for women = tend-and-befriend response
- oxytocin promotes nurturant and sociable behaviour, relaxation, reduction of fear during the stress response
What is testosterone?
- traits = aggression, sexual motivation, sociability, impulsivity, lack of inhibition, lack of conformity
- higher in stable extraversion
- not just a cause of behaviour, but also an effect
What is cortisol?
- preparation for action, normal metabolic processes
- severe stress, anxiety and depression are correlated with chronically high levels of cortisol
- chronically low levels associated with PTSD, sensation seeking, and underreactivity
What is oxytocin?
- mother-child bonding, romantic attachment, sexual response, less fearful
- facilitates all kinds of approach behaviour, both positive and negative
How does neuroticism relate to biology?
- serotonin, cortisol, norepinephrine
- right frontal lobe, left frontal lobe, amygdala, insula, anterior cingulate
How does agreeableness relate to biology?
- serotonin
- left dorsolateral prefrontal cortex, superior temporal sulcus, posterior cingulate cortex
How does conscientiousness relate to biology?
- serotonin
- middle frontal gyrus
How does extroversion relate to biology?
- dopamine, endorphins
- medial orbito-frontal cortex, nucleus accumbens, amygdala, striatum
How does openness relate to biology?
- dopamine
- left prefrontal cortex, posterior medial prefrontal cortex
What are the controversies in behavioural genetics?
- eugenics = belief that humanity could be improved through selective breeding
- cloning = belief that it might be technologically possible to produce a complete duplicate (psychological and physical) of a human being
- however, personality is a complex interaction between genes and environment, so chances are slim
What can’t heritability tell you?
- nature vs. nurture = a biologically determined trait can have zero heritability
- how genes affect personality = not informative about the process by which genes affect personality and behaviour
What does DRD4 do?
- affects development of dopamine receptors
- associated with risk for ADHD
What does 5-HTT do?
- two alleles = short and long
- short allele = score higher on measures of neuroticism, prevalence varies across cultural groups
What does COMT do?
- associated with higher levels of dopamine in the prefrontal cortex
- associated with extraversion and reasoning ability
What are gene-environment interactions?
- gene only provides the design, and so affects the behavioural phenotype indirectly
- environment can even affect heritability
- overall, the genotype is important, but only for people who have experienced a certain kind of environment
What is GWA?
- genome-wide association study
- collect data on genes, patterns of genes, and personality
- search to find which genes or patterns are associated with particular traits
What is the evolutionary approach to personality?
evolutionary approach assumes that human behavioural patterns developed because they were helpful or necessary for survival
What is altruism?
- tendency to aid and protect other people
- might help ensure the survival of one’s own genes into succeeding generations (inclusive fitness)
What is self-esteem?
evolved to monitor the degree to which a person is accepted by others
What is depression?
- two types = follows a social loss, follows failure
- reactions may have promoted survival
- pain = something has gone wrong and must be fixed
- crying = seeking social support
- fatigue and pessimism = prevent from wasting energy and resources on fruitless endeavours
What are mating strategies?
- differences stand out in mate selection and mating strategies
- differences in mate preference may reflect practical considerations in the current context rather than just instinctive, evolved biases
What is the Dark triad?
- Dark Triad = narcissism, psychopathy, machiavellianism
- mating strategy in men
What is sociosexuality?
- willingness to engage in sexual relations in the absence of a serious relationship
- for women, their accuracy of assessments of their own mate value and how often they were chosen was predicted by their agreeableness
What is the sexy son hypothesis?
instead of mating with a stable male, they take their chances with an unstable but attractive one so the son will spread numerous children
What are the two types of adaptation?
- fast-life history = reproduces multiple times at a young age, but does not devote many or any resources to protecting offspring
- live in dangerous circumstances and typically die young
- slow-life history = does not reproduce until late in life, has fewer offspring, but invests more in each one
- long-lived species
How can you account for individual differences?
- behavioural patterns evolve as reactions to particular environmental experiences
- some biologically influenced behaviours may be frequency dependent
- adjust according to how common they are in the population at large
What are the criticisms of evolutionary psychology?
- methodology = backwards speculation
- reproductive instinct = tendencies toward sexual behaviour because of past generations’ outcomes
- conservative bias = behavioural order is appropriate and inevitable
- human flexibility = describes specific behaviour as genetically programmed
- biological determinism or social structure
