Lec 8 Flashcards
(20 cards)
What is biological psychology about?
Are traits inheritable?
Can our DNA predict our traits and personality?
What is temperament?
Thomas and Chess (1977) (NYLS)
A child’s natural style of reacting emotionally and behaviorally to the world, emerges from birth when environmental input is minimal
New York Longitudinal Study: based on the parental reports, three temperament types were inferred
- Easy: general positive mood, adaptable, regular routines
- Difficult: intense emotions, irregular routines, slow to adapt
- Slow-to-warm-up: low activity, shy, slower to adapt but eventually adjust
=> these temperaments are associated with how they adjust later on in life
What did Buss and Plomin (1984) study?
Twin study to investigate childhood temperament.
They looked at four main temperament traits (natural inborn traits) - sociability, emotionality, activity, impulsivity - these were inferred from parental ratings
Results showed that identical twins were more alike in temperament compared to fraternal twins
=> suggests that genes play a role
=> supports idea that temperament is heritable
Kagan (1994)
Aim of study
Results of novelty test
- How did high reactivity react?
- As temperament tends to be stable, what kind of children would they become?
- Which behavior is this linked to?
Biological differences in inhibition
Trace differences to biological reactivity in infancy (3 time points)
Chewbacca toy (novelty test):
High reactivity: more sensitive e.g. became more upset. Supported by higher heart rate and social responses e.g. more fearful behavior seeing strangers.
=> developed to inhibited children: shy, cautious, avoidance behavior - avoid unfamiliar situations (don’t welcome novelty)
Low reactivity: curious or showed little fear (calm).
=> uninhibited children: outgoing, approach new experiences, approach behavior
Terms
Effortful control
- Ability to resist temptation
- The Marshmallow test
- small children differ in ability to regulate behavior
=> could predict later behavior to resist temptation e.g. cheating (moral conscience)
=> Parenting styles input may play a role
Temperament determinism vs Goodness of Fit model
Case study from 3 months old to adolescence
Temperament determinism: child’s temperament strongly influences their outcome (unfit environment would lead to negative outcome)
Goodness of fit: Developed by Chess and Thomas. How temperament fits environment and parent’s response to it. Meaning, children with a difficult temperament can still do well with supportive parents.
Case study: Early childhood vs Teenage years adolescence
Early childhood fits the temperament determinism model, his positive and cheerful manner suggests it would persist
Adolescence: lethargic and low-active adolescent. Goodness of fit model supports this significant change.
Environmental influence => his parents’ indulgence behavior.
Idea of evolutionary psychology:
Genes and the selection of genes
How can the Big 5 be adaptive?
Evolutionary perspective: choose the genes with the greatest chance to help you survive
=> natural or sociocultural selection, the genes that are passed on
Key: diversity in genes (individual differences) will increase ability to adapt
Big 5: gene pool doesn’t really determine our traits (think: environment). But the traits we currently have must’ve been naturally selected
Neuroticism: stress related illness, but vigilance to threats
Extraversion: Social conflict, but increase in status/partners/resources
Openness: disorganized, but creativity
Agreeableness: failure to maximize personal returns, but harmonious alliances
Conscientiousness: difficulty in adapting, but planned in premediated tasks
A man of Qi
=> environment / trait could have sped up development of astronomy
He was worried about the sky collapsing
High N, but Open to experience
=> studied astronomy
Evolutionary psychology:
Gender difference in mating strategies, Parental investment theory (Trivers, 1972) (controversial view)
When patriarchal resources are secured by men
=> not natural selection, artificial in the sense that society influences what our culture sees as “good” to man or woman
Women: Conservative strategy
They face more biological limitations, so they want to find a reliable and supportive mate
Men: Liberal strategy
Investment is small, fewer biological limitations (e.g. pregnancy for 9 months)
If reproduction is their only concern, then mating and adaptive strategies would be the advantage
Gender differences in FFM
=> Neuroticism
=> Agreeableness
Generally, women have higher neuroticism levels (take in mind effect size and sample size).
There’s a big difference for height => likely biology influenced
Smaller effect sizes for traits => how society shapes behavior?
=> Society and culture play a role in agreeableness
More gender equal societies => differences in personality are smaller (not an innate difference)
Points to take:
- Could have inherited some traits through natural selection, but not all (bc gender differences have greater diminished in developed countries in relatively short time - can’t be genetic)
- Modern skills acquired though observational learning, passed down via cultural transmission
- Cultural experiences could shape the brain
What is a major limitation of evolutionary arguments?
Potentially misleading interpretations/understanding of human behavior because it doesn’t explain the complexity of human behavior
E.g. cognition abilities as many of our skills are acquired through cultural transmission
=> behavioral genetics: to investigate what has been passed down over generations from our ancestors
Heritability of the Big 5 traits (Riemann, Angleitner, and Strelau, 1997)
Assuming rMZ = 0.5 and rDZ = 0.25, heritability is 50%, influenced of shared environment is 0%, and influence of non-shared environment is 50%.
So, personality if half genetics and unshared environment
Caveats of heritability
- Heritability seems higher if environment does not vary for everyone in the sample (over-emphasizes the importance of genes)
- Heritability shows gene impact for groups, not individuals
- Twin studies have their own limitations => there can be genetic differences in identical twins and varying environments (gene effects can also be non-linear)
Genes x Environment interaction
4
- People with different genes react different to the same environment (e.g. authoritarian parenting works differently on fearful vs fearless children)
- Genes can influence how the environment responds to a person (e.g. difficult temperament evoking authoritarian parenting)
- Genes can shape environments that match their predispositions (reciprocal determinism)
- The environment can alter gene expression => epigenetics
Weaver et al., (2006)
Rat and maternal care, insights on human neuroticism
Rats that received inadequate maternal (e.g. lack of licking) as pups exhibited increased fearfulness in response to stress
This increase was linked to certain changes in DNA methylation and histone modification of the nerve growth factor-inducible protein A => this activity became reduced, showing more fear (chain of biological processes involving stress hormones)
Reversing these epigenetic mechanisms also reversed the impact of poor maternal care on fearfulness
=> When we examine the epigenetic effect of parenting quality and bullying victimization on stress response
Molecular genetics and personality
Personality traits are partly inherited
Behavioral genetics show about 50% of our personality differences (variance) come from genes
Genes => proteins => biological process => personality traits (?)
How genes turn into personalities traits is very complex because there are thousands of genes with a tiny effect, so lies a big gap
We haven’t found specific genes yet, studying one gene at a time doesn’t work well
=> scientists use big studies (GWAS) to look for patterns across the whole genome
Luciano et al. (2018)
GWAS study
Looking for gene pathways (grow, connect and communicate)
- Neuron spine (communication of brain cells)
- Cell adhesion molecules (form networks)
- Neuron differentiation (specialization)
- Neurogenesis (creation of new brain cells)
=> over 100 genes working together in the brain
Results: associating single nucleotide polymorphism (SNPs) - part of genes - with neuroticism
3% of variance for neuroticism explained at best
Hormonal responses and personality
(Mapping personality traits to distinctive patterns of hormonal responses)
- High levels of conscientiousness tend to exhibit lower levels of cortisol (hair samples)
- Testosterone shows weak association with agressiveness
- Administrated of oxytocin may increase reported trust but later replications found insignificant results
=> debatable topic if traits can be registered to stable hormonal response patterns
MRI studies caveats and results from Simon et al., 2020
- small sample sizes often
- no correction for false positive rate
- brain activities recorded are not very reliable
=> more realistic to study a network of activation, rather than regions
Simon et al., 2020
- Neuroticsm negative (weak) association with Ventral and Dorsal attention networks
- Openness positive association with DMN (spontaneous mental activities e.g. daydreaming)
Ways to study biological basis of personality (each has own weaknesses)
- temperament research
- behavioral genetics => heritability
- molecular genetics
- physiological responses (hormone response patterns)
- brain regions / networks and neurotransmitters
Note:
perhaps unrealistic to adopt the top-down approach - starting with personality traits we can observe => looking inside the brain to see what biological processes cause these traits
