PSY2042_Week_6_Lecture_Biological_Foundations_and_Personality_Development_

School of Psychological Sciences Lecture Overview

• Course: PSY2042 Personality and Social Psychology

• Week 6 Lecture by Amanda Foon

• Topics Covered:

  • Brain structure and personality traits

  • The Big Five and the brain

  • Nature vs. nurture in personality

  • Twin studies relevance

  • Gene-environment interactions and epigenetics

  • Temperament and neurotransmitters

  • Psychophysiology and personality

Welcome Message

• Acknowledgment of Country: Continuous connection to land, waters, and culture of Kulin Nations.

Week 6 Learning Objectives

• Understand complexities of the nature/nurture debate.

• Recognize genetic and environmental personality influences.

• Appreciate interplay of genetic and environmental factors.

• Define and explain epigenetics.

• Explain theories linking neurophysiology to personality.

• Connect brain function to complex psychological functions.

Personality Neuroscience Goals

1. Identify neural substrates of personality.

2. Understand genetic/environmental influences on stable brain function patterns associated with personality traits.

Biological Models of Personality History

Key Figures and Studies

• Francis Galton: Nurture vs. nature perspective through twin studies.

• Gordon Allport: Proposed personality influenced by both biology and environment.

• John Harlow: Case of Phineas Gage linked brain damage to personality changes.

• Charles Darwin: Introduced evolutionary perspectives on behavior and personality.

Important Milestones

• 1859: Darwin's "On the Origin of Species" introduces evolution by natural selection.

• 1970s-1990s: Use of advanced techniques like MRI and functional MRI (fMRI) to study brain activity related to personality.

Brain Structure and Personality Traits

Neural Basis of Traits

• Certain brain regions linked to specific personality traits:

  • Extraversion: Medial Orbitofrontal Cortex

  • Conscientiousness: Middle Frontal Gyrus

  • Agreeableness: Superior Temporal Sulcus

  • Neuroticism: Dorsomedial PFC, Cingulate Gyrus/Caudate

Case Study: Phineas Gage

• Significant impact on understanding decision making, behavioral regulation, and emotional control after frontal lobe injury.

Research Methods in Personality Neuroscience

• Studies typically utilize fMRI to examine relationships between brain structure and personality traits, demonstrating neural region associations.

The Big Five Personality Traits and Neural Activation

• Extraversion & Brain: Linked to increased medial orbitofrontal cortex activity.

• Conscientiousness: Related to middle frontal gyrus involvement.

• Agreeableness: Activity in the temporoparietal junction during emotional decisions.

• Neuroticism: Involves activation in the amygdala during emotional regulation.

Understanding Nature and Nurture in Personality

Definitions

• Nature: Genotypes (inherited) vs. Phenotypes (observable traits).

• Nurture: Shared (family-environment) vs. Non-shared (individual differences within families) environments.

Twin Studies and Heritability of Personality

Relevance

• Monozygotic vs. dizygotic twins used to assess genetic/environmental influences.

Heritability Coefficient

• Score from 0.0 (no genetic variance) to 1.0 (total genetic variance).

• Approximately 50% personality variation attributed to genetics; non-shared factors account for the rest.

Epigenetics and Gene-Environment Interactions

• Epigenetics: Genetic changes affecting expression without altering DNA sequences, demonstrating environmental effects on personality traits.

Temperament and Neurotransmitters

Definitions

• Temperament: Inherent physical, mental, and emotional traits; stable over time.

Theories of Temperament

• Thomas & Chess: Different clusters (easy, difficult, slow-to-warm-up) based on behavioral responses.

• Cloninger's Model: Associating neurotransmitter activity with personality dimensions.

Psychophysiology and Personality

• Connections between physiological processes and personality traits.

• Key Theories: Eysenck’s arousal theory and Gray’s BAS/BIS model.

Summary

• Personality traits correlate with specific neural activation patterns.

• Activation levels reflect differences in personality strength and development.

• Influences of genetics and environment are crucial in shaping personality.