Biological Aspects of Personality

Theories of PersonalityPrepared by: Jim Messina,

Ph.D.

Key Biological Theorists Charles Darwin Ivan Pavlov Hans Eysenck 1916-1997 Francis Galton

Evolutionary Personality Theory Application of Darwin’s Theory

of Evolution Function of a survival

characteristic evolves over time

Belief that many of individual characteristics are “in our bones” in our genes

Natural Selection Process by which certain

adaptive characteristics emerge over generations

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

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

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

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

Nervous System Arousal Stable people-well-modulated

nervous systems Neurotic people-very reactive

nervous systems

Tests: EEG, Electrodermal measure (lie detector)

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

The Brain Brain reaches its maximum

number of synaptic connections and its greatest metabolic activity around age 3 or 4

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

Top view of Brain

1. genu of the corpus collosum2. head of caudate nucleus3. putamen4. globus pallidus5. thalamus6. tail of caudate nucleus7. splenium of corpus callosum8. amygdala9. substantia nigra

PET Scan of Brain of Adult with ADHD

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

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

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

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

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

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

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

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

Eysenck’s 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

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

Eugenics Good Birth or Good Genes is the

cause of peoples’ high intelligence and stable emotional well-being

Recommend forced sterilization of the poor

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.

Mediated effects of Biology Disease-Parkinson’s, ear, heart,

lung, systemic, surgery Poisoning-mercury, lead,

manganese Brain disease-Alzheimer’s, strokes,

epilepsy, tumors Illegal drugs, LSD, cocaine, crack

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

Survival of the Fittest Darwin’s concept that the fittest

survive over time Misused to mean: weak creatures

should not survive Pseudoscientific justification for

the oppression of minorities

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

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

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

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

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