Psychology of Personality - Biological Domain

PSYC 3370

biological domain of personality

3 approaches

• genetic

• physiology

• evolutionary

nature vs nurture

do genetic or environmental factors determine personality?

both, there may be genetic predispositions but there is no true guarantee due to various influences

also how do you define any one personality trait?

human genome

all of the DNA/genes somebody has in their body

eugenics

the practice of trying to breed for certain genes and get rid of others

• ethical controversies:

  • government intervention

  • should someone be able to pick and choose depending on behavior/personality/condition/disorders/etc?

heritability

chances of you having a certain trait

• genotype: your alleles

• phenotype: physical expression of those traits

family studies

look back at ancestors and generations to determine heritability

twin studies

uses monozygotic twins that come from the same egg due to being genetically identical to measure nature vs nurture

50% of influence for Neuroticism and Extraversion comes from genetics

51%

• dizygotic twins are only fraternal, they are not identical but born at the same time from 2 separate eggs

adoption studies

how much do adopted children differ from their biological vs adoptive parents → also nature vs nurture

no correlation between adoptees and parents, but in another they found that it was 40% and 30% for neuroticism and extraversion in terms of heritability

genetic-environment interaction

genetic dispositions can be dormant or awakened by the environment, bi-directional effect

• passive genotype-environmental correlation

• evocative/reactive genotype-environmental correlation

• active genotype-environmental correlation

passive genotype-environmental correlation (genetic-environment interaction)

child put in environments they cannot control

evocative/reactive genotype-environmental correlation (genetic-environment interaction)

child’s genotype causes different responses from others

active genotype-environmental correlation (genetic-environment interaction)

child’s genotype influences them to seek out particular environment

political leanings and nature/nature

depends on both

physiological approach to personality

instead of genetics/heredity, focus on how our bodies and brains affect personality

• neurons, neurotransmitters, brain structure, injuries, infections

neurons

nerve cells that connect to each other to send signals

• dendrites collect

• axons send away

• synapse is the gap between

neurotransmitters

hormones, chemical messengers

• serotonin, norepinephrine, dopamine, cortisol, etc

limbic center

deals with mood regulation

phineas gage

had brain injury that changed his personality

physiology measures

electrodermal activity, skin conduction, nervous system, polygraph

central nervous system

brain, spinal cord

peripheral nervous system

everything outside of your brain and spinal cord

• autonomic nervous system

  • sympathetic

  • parasympathetic

autonomic nervous system

automatic function control

sympathetic nervous system

fight or flight

• adrenaline, heart rate, suppression of PSNS, stress

parasympathetic nervous system

digestion, resting

heart rate variability

personality can affect your control over this

• exercise, adrenaline, physical activity → up

• relaxing, breathing → down

cardiac reactivity of type a vs type b

type a: go getter, workaholic, perfectionist → associated with cardiac reactivity → higher chance of heart attack, stress, etc

type b: laidback, smell the flowers

brain activity and extraversion

extroverts vs introverts differ here as well

reinforcement sensitivity

how sensitive you are towards rewards and punishment depends on your systems here

• behavioral activation systems (BAS) → dopamine, incentives, rewards
  behavioral inhibition systems (BIS) → anxiety, frustration, uncertainty, punishment, avoidance

impulsivity

how likely you are to act on urges without thinking → affects your sensitivity towards reward/punishment

sensation-seeking/depriving

optimal level of arousal/stimulation varies from person to person

• higher need for arousal → thrill-seeking

harm avoidance

connected with serotonin

reward dependence

connected with levels of norepinephrine

morning person/night owl

depends on your personal circadian rhythm/sleep-wake cycle

evolutionary approach to personality

what traits made it through natural selection

genes and inclusive fitness

the strongest, healthiest people reproduce, creating increasingly strong/healthy generations with better genes

charles darwin

genetics, evolution, natural selection, fitness

hostile forces of nature

what makes it less likely for organisms to survive

• predators, natural disasters, heat, infection/diseases, starvation

sexual selection

choosing a mate based on

• appearance, fitness, intelligence, health, etc

genes and reproduction

the most adapted organisms survive to pass down their genes

human nature and the need to belong

most people want to feel accepted in a group, so we have evolved to avoid being left out

• helping and altruism

universal emotions

across cultures, humans can recognize 7 distinct facial expressions showing basic emotions

sex differences

causes changes in personality, testosterone and aggression, mate selection, reproductive success and jealousy