Chapter 4: Biological Theories -- Genetics, Physiology and Evolution Flashcards
Behavioural Genetics
This refers to the use of genetic methods to determine the origins of individual differences in behaviour. Essentially, it is attributing personality to genetics.
Nature vs. Nurture
In the politics of behavioural genetics, it had heavy focus on the nature side, discounting the role of parenting. This promoted the perception that “your genes are what you are.”
Political Agendas
Biological determinism was used to minimize responsibility, and argue a lack of free will against crimes.
Biological Determinism
A belief that one’s biology is what influences behaviour. For instance, “my genes made me do it!”
Eugenics
To encourage or discourage certain genes from existing in the population gene pool. This eliminated diversity and was weaponized against marginalized groups.
Francis Galton
Coined the term Eugenics. Conducted research to discover that not just physical traits could be passed down but also personality. Intended to use eugenics to make society better.
World War II
Nazis used eugenics as a mask to reason the genocide of Jews.
Alberta Sterilization Act
The government believed that the adults who had lower IQ would have offsprings of lower IQ as well. To “solve” this issue, they turned to eugenics and forced sterilization on children who were “mentally weak”. Although they did not account for differences relating to socioeconomic factors, or environment (rural areas vs. urban).
What trait is super nature-based?
Aggression!
Richard Tremblay
Attempted to study the age in which we can predict and intervene in aggression in adolescent boys. Started observations in high school male adolescents and eventually rolled back his hypothesis until he began to examine fetuses.
Heritability
The number of individual differences that can be attributed to genetics. This does NOT mean the probability of inheriting the trait. It simply indicates the number of population differences that are a result of genetics.
How do you refine the limitation of personality being affected by BOTH Nature AND Nurture?
We need to measure both factors! We need to examine the correlation between the individual’s traits and the different aspects of their environment. Example: The number of books in a child’s home vs. IQ.
Monozygotic Twins
One zygote (one sperm and one egg) splits into two. They are identical in DNA and appearance and share the same genetic material and environment.
Dizygotic Twins
Two zygotes formed due to two eggs being released. Genetically different just like other/regular siblings, although they share a prenatal experience/environment.
Occupational Preferences
When looking at the occupational preferences between the parent’s actual job and child’s preferences, what was found was that the child’s ideal career may be different, but the attributes of the ideal career are similar in values the parents hold. Preferences of occupational attributes have high heritability.
Drinking and Smoking
Both are highly heritable and are related to high extraversion, sensation seekings and neuroticism.
Monozygotic twins are likely to have a twin that also smokes, and alcoholism has high heritability (but not social drinking).
Molecular Genetics
Specific genes are associated with specific traits.
Dopamine Alleles
Long repeated allele versions cause individuals to have a higher threshold for dopamine response, meaning they need more stimulus and novel experiences to be satisfied.
Short repeated allele versions cause individuals to have lower dopamine thresholds for dopamine response, meaning they are easily satisfied and too much stimulus may be overwhelming.
Cultural Differences in Dopamine
Longer alleles are more prevalent in Americans as opposed to Asians, accounting for cultural differences.
Galen Medicine
In Medival Europe, they contributed personality to 4 humours/bodily fluids:
1) Phlegm (Water) – Passive, calm, thoughtful
2) Blood (Air) – Happy, outgoing, lively
3) Yellow Bile (Fire) – Unstable, Aggressive
4) Black Bile (Earth) – Unhappy, Pessimistic
Ayurveda Medicine
In India, they tied personality to body types.
1) Vata: Thin, light and airy, dry skin = Anxious, active and creative mind.
2) Pitta: Medium build, prone to inflammation, hot = Intelligent, focused, energetic and intense.
3) Kapha: Stocky build = Nurturing, compassionate, more grounded.
Phrenology
In North America, it was believed that the measurements of your heads tied to personality. The bumps around your head would indicate what parts of the brain were under-developed or over-developed.
Hebb’s Theory of Arousal
There is an optimal level of arousal and alertness.
Too low/under aroused: Sleepy, tired, bored.
Too high/over aroused: Anxious, agitated, overworked.
Cortisol Levels and Personality
Introversion and Extraversion are biologically based as the blood-brain barrier allows for more cortisol for introverts and less for extraverts.
What part of the brain is in charge of personality?
The prefrontal cortex. It also is in charge of self-control, planning, judgement, rationalizing, and time and task management.
Left Hemisphere in Prefrontal Cortex
Calm and emotionally stable. This hemisphere deals with pleasant emotions! The calmer your brain, the greater your left-side asymmetry.
Right Hemisphere in Prefrontal Cortex
Neurotic. This hemisphere deals with unpleasant emotions. The more asymmetric your right hemisphere, the more preoccupied your brain tends to be.
Gray’s Theory of Behavioural Activation System (BAS)
Motivation through reward/gain! Sensation-seeking and impulsive, as well as more positive outlook and likeliness to see the possibilities of wins. Maps highly with Eysenck’s definition of Extraversion.
Gray’s Theory of Behavioural Inhibition System (BIS)
Motivated by punishment avoidance. Preoccupied with negative outcomes, and tends to be anxious, as well as possess a negative outlook and focus on the possibilities to lose. Maps highly with Eysenck’s definition of Neuroticism.
Neurotransmitters and Personality
Dopamine: People with low dopamine thresholds need less stimulus to be satisfied. Those with high dopamine thresholds thend to be thrill-seekers.
Serotonin: In charge of mood regulation. Too low may lead to depression, while too high may lead to hypomania.
Norepinephrine: Linked to our levels of adrenaline, and is reward-dependent.
Cooperation vs. Competition
Must be balanced because too much of one causes the other to become the more beneficial option.
