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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.