lec 10

Basis of Personality

• Introduction to the nature versus nurture debate regarding personality.

  • Nature: Argues personality is predetermined by genetics and biological structures.

  • Nurture: Claims individuals are born as 'blank slates' (tabula rasa), shaped by environmental factors such as upbringing and life experiences.

  • Ongoing discussion indicates both elements are influential.

• Emphasis on the need for a biological basis for personality.

  • Real traits must be grounded in some biological aspect, likely within the brain.

  • Personality cannot be pinned to a single brain region; various biological systems are involved.

Methodological Approaches in Personality Psychology

• Overview of four key methodological approaches to studying the biological basis of personality:

  1. Brain Damage

  2. Brain Stimulation

  3. Brain Imaging

  4. DNA Sequencing

Brain Damage

• Understanding brain damage as a method to analyze personality changes.

  • Phineas Gage: A case study demonstrating how significant brain damage affected personality.

    • Railroad spike accident caused alterations in behavior and personality associated with frontal lobe damage.

  • Brain damage can occur through various means (trauma, tumors, medical conditions).

  • Lobotomy: Historical example illustrating the effects of brain structure damage on emotion and personality.

    • Used to reduce emotional experiences but had troubling ethical implications.

  • Split Brain Surgery: Severing the corpus callosum to alleviate severe seizures, and the consequences on personality and cognition.

Brain Stimulation

• Techniques to stimulate brain regions and observe effects on personality.

  • Invasive methods using electrodes to stimulate specific regions and observe outcomes.

  • Parkinson's Disease Example: Patient's personality dramatically shifted during deep brain stimulation, showcasing how stimulation can impact emotional state.

  • Transmagnetic Stimulation (TMS): Non-invasive magnetic field application that temporarily disables brain regions to study effects on behavior.

    • Useful for ethical experimentation on the brain's function.

Brain Imaging

• Techniques that visualize brain activity without altering its structure.

  • EEGs/MEGs: Measure electrical/magnetic activity in the brain, providing real-time data but with low localization.

  • PET scans: Track tracer chemicals to visualize blood flow in different brain regions, indicating areas of activity.

  • MRIs/FMRIs: Provide detailed images/videos of brain structure and function, respectively, measuring blood oxygenation as an indicator of activity.

• Importance of understanding both temporal resolution (speed) and spatial resolution (specificity) in selecting imaging methods for research.

DNA Sequencing

• Modern approach to understanding the genetic basis of personality traits.

  • Involves mapping an individual's genome and correlating genetic information with personality measurements.

  • Challenges include the complexity of genetic influences and the risk of false positives due to vast numbers of comparisons.

    • Complex personality traits often arise from interactions of multiple genes, rather than a single "extroversion gene."

Conclusion

• Personality psychologists utilize brain damage studies, stimulation, imaging techniques, and DNA sequencing to explore the biological foundations of personality.

• Ongoing research continues to unravel the intricate relationships between biology and personality traits.