Biological Aspects of Personality

Transcription

1 Biological Aspects of Personality Introduction By the end of this Unit, you should be able to: explain biological factors that influence personality development, relate environmental influences to temperament. 1

2 Direct Genetic Effects Natural selection and pragmatism Natural selection the process by which adaptive characteristics (behavioural tendencies and emotions -"personality ) emerge over generations Evolutionary personality theory Darwin s ideas on the function of a characteristic in survival Direct Genetic Effects Example: Angelman Syndrome A congenital (inborn) disorder caused by a defect on chromosome 15 Happy, cheerful, attractive, friendly Mental retardation and jerky movement Demonstrates how genetic factors set before birth can dramatically influence later personality Example: William s Syndrome(William-Beuren Syndrome) A neuro-developmental disorder Excessively sociable, limited intellect 2

3 Sensation Seeking and Addiction Proneness Zuckerman's Theory Those high on "sensation seeking" have a low level of internal arousal, so they are drawn to novel and exciting experiences It is likely that some people have natural defects or diseasecaused weaknesses in their dopamine systems, and such people may be unusually susceptible to addiction Twins as a Source of Data Comparing identical twins to fraternal twins makes it possible to detect genetic influences on personality Minnesota Twin Studies Have found impressive similarities in personality between people who have the same genetic make-up 3

4 The Case of Schizophrenia Twin studies have helped to show that schizophrenia is genetically influenced Structural abnormalities have been found in the brains of schizophrenics There is a genetic predisposition to schizophrenia However, schizophrenia is not simply a genetic disease Consensus between identical twins is far from perfect Sexual Identity and Homosexuality Twin studies have shown that homosexuality may have slight genetic influence However, there appears to be some environmental influences as well, like personal choices. 4

5 Mediated Effects of Biology Effects through environmental toxins Poisoning "Mad as a hatter" - hat makers suffered brain damage when exposed to mercury in hatmaking factories Lead poisoning and cognitive/behavioural deficits in children Manganese miners and fighting behaviour Mediated Effects of Biology Effects through physical illness Personality can sometimes drastically change as a result of Alzheimer s disease Strokes Temporal lobe epilepsy Various surgical procedures Dementia 5

6 Mediated Effects of Biology Effects from legal and illegal drugs Widely prescribed drugs such as tranquilisers (like Valium), sleeping pills (like Halcion), and various antidepressants have short-term and sometimes long-term effects on personality Cocaine tends to produce these: Users may worry, develop symptoms of paranoia obsessed with details, and feel they are being persecuted Effects from Reactions of Others Physical characteristics influence the way others treat us, and thereby mould our views of the world - our personalities Physical Attractiveness Stereotypes People tend to expect attractive people to do good and be good Adults have higher expectations for attractive children 6

7 The Biological Approach Implications for Therapy Since behaviour is seen as resulting from evolved biological structures, therapy is focused on biological interventions: psychotropic drugs like Prozac or Valium for mental illness hormones for conditions such as PMS irritability antihistamines or cleaner environments for allergy and toxin-related conditions Eventually, gene therapies may become common, and the rise of moral concerns evident. Summary Genes affect personality development as seen from twin studies. Genes also interact with the environment. Though reactions from others may affect individuals, strengths, talents and competencies build confidence, and individuals will objectively evaluate what people tell them. 7

8 Reflection Questions 1. How do genes influence our behaviour and mental processes? 2. What aspects of your personality are inherited, and what aspects are not? 3. How do environmental toxins and illnesses affect personality? 4. Why do reactions of others affect one s personality development in varying degrees? References Bouchard, T.J.Jr. (2004). Genetic influence on human psychological traits: A survey. Current Directions in Psychological Science, 13, Fagala, G.E. & Wigg C.L. (1992). Psychiatric manifestations of mercury poisoning. Journal of the American Academy of Child and Adolescent Psychiatry, 31(2), Friedman, H.S. & Schustack, M.W. (2014). Personality: Classic theories and modern research. Harlow, UK: Pearson Education Limited. Tellegen, A., Lykken, D.T., Bouchard, T.J. Jr., Wilcox, K.J., Segal, N.L., & Rich, S. (1988). Personality similarity in twins reared apart and together. Journal of Personality and Social Psychology, 54, Zuckerman, M. & Kuhlman, D.M. (2000). Personality and risk-taking: Common biosocial factors (Special issue: Personality processes and problem behaviour). Journal of Personality, 68,