Biological Bases Of Personality and Intelligence Flashcards
Brain Injury Inducing Personality change
(Forbes et al 2014)
- Brain damage associated with high neuroticism and low consciousness
- Phineas Gage - Personality changed after work place injury
Trait Theories
Hans Eysenck
- Traits are inherited
- There are two dimensions: Extraversion and Neuroticism
- The scale of extroversion is dependent on cortical arousal
- The scale of neuroticism is dependent on limbic system
What is Extraversion
Hans Eysenck
- Balance of ‘inhibition’ and ‘excitation’ in the brain
- Excitation = brain an alert learning state
- Inhibition = brain calming itself down protecting itself in an overwhelming stimulation
- Extraverts have good, strong inhibition
- Introverts have poor or weak inhibition
Stereotyped Behaviour
Extraverts and introverts
(Eysenck)
Extraverts are:
- Seek arousal
- Stimulus Hungry
Introverts:
- Prone to over arousal
- Stimulus shy
Neuroticism
Eysenck
- Ranges from calm to nervous
- Genetically based and physiological research
Eysencks Ascending Reticular Activating System - Look at images
Support for Eysenck’s Theory
- Introverts like less noise than extroverts
- Introverts require more depressant drugs
- Introverts show higher EEG alpha activity when aroused
Problems with Eysencks theory
- Genetic components are not clear enough in terms of the link with extraversion.
- Some study’s have shown different results where people with higher neuroticism have smaller physiological reactions to stress
Five Factor Model
- Model doesn’t provide evidence for how external factors affect biological basis
Hsu et al (2018)
- 810 participants used to generate networks of brain activity patterns
Reinforcement Sensitivity Theory
Gray (1981)
Proposed three neurological systems as underlying personality
- Behavioural approach system
- Behavioural inhibition system
- Fight Flight Freeze
- Attention to environment rewards and punishments shape behaviour and reflect in personality
Behavioural Approach System
- Extraverted
- Positive character
- Impulsive
- People with high impulsivity are highly sensitive to reward
Behavioural Inhibition System
- Negative emotion
- Neurotic personality trait
- Withdrawal from threat
- People with high anxiety are highly sensitive to signals of punishment
Flight Fright Freeze System
- Underlying neurological system for response to threat
- Triggers responsive behaviour, allows you to escape
Evidence for Gray’s Theory
(Revelle et al, 1980)
- Moderate dosage of caffeine hindered the performance of introverts and helped the performance of extraverts on a cognitive task
- Supports Gray’s theory but challenges Eysencks theory.
Eysenck Vs Gray
- Gray’s theory explains a narrower rage of findings
- Biological trait might not right for explaining behaviour traits.
-Research should focus on cognitive or social bases of personality?
What are the 3 contributions to a trait
- Genetics
- Shared environment
- Non - shared environment
Additive Genetic Variance
- Affect on a trait stemming from one or more gene loci
Dominant Genetic Variance
- Certain genes are expressed and others aren’t
Epistatic Genetic Variance
- Genes and environment can interact, particular genes are only expressed in specific circumstances.
What is a non-shared environment
- Socialisation out side of the home
- Transmission of culture by a group process
- Context specific socialisation
Reimann (1997)
twin study - personality
- Heritability = 2xdifference between mz twin correlation rate and dz twin correlation rate
- The heritability of extraversion is 56%
Intelligence
Twin Studies
- Identical twins reared together have 86% concordance rate
- Identical twins reared apart have 76% concordance rate
Adoption Studies
- MZ stwins can have different uterine environments
- MZ twins who share the same DNA sequence have different epigenetics at birth
Personality and Genes
- There have been links between dopamine genes and impulsivity (Mumafo et al, 2008)
Genes may not play a role in personality
- It can be hard to identify that common genetic variants influence personality traits even with large samples.
- We need much larger samples as well as more complex, reliable technology
