Biological Aspects of Personality

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Biological Aspects of Personality

• Theories of Personality
• Prepared by Jim Messina, Ph.D.

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Key Biological Theorists

• Charles Darwin
• Ivan Pavlov
• Hans Eysenck 1916-1997
• Francis Galton

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Evolutionary Personality Theory

• Application of Darwins Theory of Evolution
• Function of a survival characteristic evolves
  over time
• Belief that many of individual characteristics
  are in our bones in our genes

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Natural Selection

• Process by which certain adaptive characteristics
  emerge over generations

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Examples of Genetic Personality Types

• Angelman Syndrome chromosome 15
• Friendly
• Oral driven
• Downs Syndrome - chromosome 21
• Friendly easy to get along with
• Caring, Loving
• Approval seeking

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Study of Temperaments-Based on Work of Pavlov

• Temperament stable individual differences in
  emotional reactivity which remain stable as
  children mature
• Different nervous system responses to unpleasant
  stimuli

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4 Basic Aspects of Temperament

• Social-Introversion-Extroversion- seek or avoid
  being with/in front people
• Emotionality-fearful, angry, mood swings vs
  relaxed, calm, placid, stable
• Activity-vigorous, always in motion vs passive,
  lethargic
• Impulsive-aggressive-bully vs peace maker, plans
  vs quick changes, cold vs conscientious friendly

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Introversion vs Extroversion

• Hans Eysenck ties this to central nervous
  system Biologically based personality theory
• Extroverts Low level of Brain arousal and seek
  stimulation
• Introverts High level of Brain arousal shy away
  from over-stimulation

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Nervous System Arousal

• Stable people-well-modulated nervous systems
• Neurotic people-very reactive nervous systems
• Tests EEG, Electrodermal measure (lie detector)

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Sensation Seeking

• Seek new challenge or new high
• Seek highly stimulating activities
• Attracted to unknown
• Low level of natural (internal biological)
  activation seek arousal from environment
• Left and right side of Brain

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The Brain

• Brain reaches its maximum number of synaptic
  connections and its greatest metabolic activity
  around age 3 or 4

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Brain Hemispheric Hypothesis

• Left side of Brain-Role in Positive
  Emotions-Creative side of Brain
• Right side of Brain-Role in Negative
  Emotions-Methodological, systematic side of Brain
• Try out this test to get the impact of right and
  left hemisphere operations

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Top view of Brain

• genu of the corpus collosum
• head of caudate nucleus
• putamen
• globus pallidus
• thalamus
• tail of caudate nucleus
• splenium of corpus callosum
• amygdala
• substantia nigra

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PET Scan of Brain of Adult with ADHD
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PET Scans

• Demonstrates metabolism of glucose in brain under
  arousal
• Brain on left is normal adult brain under arousal
• Brain on right is Brain of Adult with ADHD
• frontal lobe of brain most involved in adults
  with ADHD

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Messages from Brain Travel by Nervous System

• The Central Nervous System is the Communications
  Highway of the body
• Brings help to the body based on the messages it
  screens from the environment

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Neurons where the messages are delivered!

• Bio-chemical electrical impulses create a cascade
  of effects based on the message sent to various
  organ receptors of the body

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Neurotransmitters Impacted Too!

• Not only are there physiological changes but
  there is altering of neurotransmitters based on
  messages from brain
• Absence or overabundance can create whole new set
  of consequences

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Neurotransmitters

• Brain Billions of Brain Cells-Neurons
• Neurons transmit information electrical
  conduction within nerve cells between nerve
  cells
• Message once carried through body cell (Axon)
  crosses space Synapse to receiving cell

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Neurotransmitters

• Tip of Axon-tiny sacs contain neurotransmitter
  chemicals which are automatically released by
  sending nerve cell
• Neurotransmitter chemicals excite receiving cell
  causing cell to fire to send message through its
  own body-Axon to next receiving cell
• Once message received neurotransmitter is
  deactivated and taken up from synapse and stored
  in sacs so as not to cause repeated firing of the
  receiving cell

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Types of Neurotransmitters

• Dopamine-dopaminergic system
• Norepinephrine-noradrenergic system
• Serotonin-serotonergic system
• Control senses, thinking, perception, mood,
  attention, and behavior
• Unfortunately at this time we can not measure
  amount for baseline therapeutic levels

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Hans Eysenck-

• 3 Type Theory Biological Determinism-Heredity in
  Everything
• E Extraversion linked to ascending reticular
  activating system (ARAS)-reticular formation of
  Brain Stem
• N Neuroticism linked to limbic system-brains
  emotional center regulates sex, fear aggression
• P Psychoticism linked to endocrine
  gland-especially which controls sex drive

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Eysencks Types

• E-extraversion introversion
• Neuroticism-stability
• Psychoticism-superego functioning
• People show degrees of all 3 types
• Encouraged Twin studies especially of identical
  twins who were adopted separately

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Sir Francis Galton

• Supposition that Upper Class Englishmen were a
  superior population
• Began the study of adoptive twins
• Began the eugenics movement
• Encouraged eminent families to have lots of
  children to improve the human blood lines

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Eugenics

• Good Birth or Good Genes is the cause of peoples
  high intelligence and stable emotional well-being
• Recommend forced sterilization of the poor

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Kin Selection

• Nieces and nephews of people with certain traits
  thought to be genetic based- homosexuality,
  schizophrenia, bipolar disorder genetic
  tendency toward these conditions survives since
  nephews and nieces share some genetic makeup with
  uncle or aunt who has these traits.

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Mediated effects of Biology

• Disease-Parkinsons, ear, heart, lung, systemic,
  surgery
• Poisoning-mercury, lead, manganese
• Brain disease-Alzheimers, strokes, epilepsy,
  tumors
• Illegal drugs, LSD, cocaine, crack

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Somatotypology-W.H.Sheldon, 1942

• Three Body Types have influence on personality
• Mesomorphs-muscular, large boned, athletic
• Ectomorphs- slender, bookworm
• Endomorphs- overweight, roly-poly, good natured

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Survival of the Fittest

• Darwins concept that the fittest survive over
  time
• Misused to mean weak creatures should not
  survive
• Pseudoscientific justification for the oppression
  of minorities

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Social Darwinism

• Applying evolutionary theory in a crude way to
  society
• Not only individuals but societies and cultures
  naturally compete in survival of the fittest
• It was ok to subjugate those seen as inferior
  race or culture

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Sociobiology

• Scientific study of the influence of evolutionary
  biology on individual responses regarding social
  matters
• Focus Analysis of human aggression, human
  courtship and raising young children

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Attachment

• Close bond develops shortly after birth between
  infant and caretaker(mother)
• Infant clings, gurgles, smiles to attract
  caregiver-so that caregiver will nurture the
  infant
• Attachment system insures survival of the of
  infant-ensures passing of mothers genes
• Evolutionary function for cuteness of infants

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Human Genome Project

• The accomplished task of identifying the tens of
  thousands of genes in chromosomes
• Develop treatments for inherited diseases
• Movement towards Gene Therapy
• Potential threat genetic engineering

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Biological Determination

• Personality simply a matter of genes, brains, and
  hormones
• Behavior is determined by biological tendencies
• Minimizes the human potential for growth and
  change