1. Biological Approach AS psychology

2. Biological Approach The influence and impact of genes and the nervous system on individual differences Describe the influence of genes, hormones and brain lateralization on gender differences

3. Central Nervous System Brain and spinal cord Neurones ▫cells of the nervous system

4. Role of Neurotransmitters Synapse (synaptic gap) ▫space between the nerve cells Receptors ▫Cells that accept the transmitter molecules Neurotransmitters ▫Specific molecules that are released and they have a specific action  Epinephrine  Dopamine  serotonin

5. Role of Neurotransmitters

6. How messages pass across the gap Start at pre-synaptic axon (brain or sensory cell) Electrical signal travel to the terminal button where the neurotransmitters are stored in vesicles Neurotransmitters are released and they cross the synaptic gap (cleft) On the other side (post synaptic dendrite) receptors collect the neurotransmitters and new signal starts Neurotransmitter is either reabsorbed or it breaks down

7. We have millions of synaptic gaps

8. Behaviour Depending on the amount and type of neurotransmitter ▫Neuron will “fire”- excite the next neuron ▫Neuron will not “fire” –inhibit Pleasure, pain, consciousness are controlled by neurotransmitters Medications mimic/inhibit them

9. Hormones Made and released by endocrine glands ▫Pituitary gland ▫Adrenal glands ▫Ovaries, testes Control the balance of many things within the body ▫Reproductive health ▫Metabolism ▫Stress response  Fight or flight

10. Nature versus Nurture NatureNurture Genes- DNA Hormones Neurotransmitters Evolution We are not in control of our actions Environment Nutrition Stimulation Education We have control of our actions

11. Biology and Gender Development Sex chromosomes XX- girl XY- boy Initially the foetus is identical- has tissue that can develop into either girl (Mullerian) or boy (Wolffian)

12. Gender development the gonads develop at 6 weeks Y-chromosome gene called SRY produces testis- determining factor Default gender for foetus is female ▫All will develop into girls unless there is a Y chromosome stimulating the development of boy

13. Influence of hormones Presence or absence of testosterone influences sex differences  If testosterone- male hormones released  No testosterone- female hormones released

14. Gender development Exposure to male and female hormones before and after birth is responsible for physical differences

15. Case Study: David Reimer (Money, 1995) Money believed that gender ▫was determined by social experience after birth and the result of our upbringing (nurture) ▫Children are born gender neutral ▫Male and female children are “created” by societal norms

16. Case Study: background 1965: twin boys born (Bruce and Brian) ▫Identical twins raised as different genders Circumcision at 10 months- ▫Bruce lost his penis due to a terrible mistake ▫Parents had seen Dr. Money on TV talking about intersex children ▫Consented to raise “Bruce” as a girl “Brenda” ▫1967- surgical castration- removal of the testes ▫At age 12- given estrogens

17. Analysis Brenda’s transition to female-hood was not easy ▫Masculine traits (guns and other male toys) ▫Involved in fights ▫Urinated standing up ▫Many behavioural and emotional issues with being a girl ▫At 15- changed back to a boy (David) with reconstructive surgery

18. Case study continued David much happier that “Brenda” ▫Married and had step children ▫Sad ending- his brother committed suicide and he became depressed and also committed suicide at the age of 38 Conclusion ▫This study shows the power of genetics (nature) in gender in determination- contrary to what Dr. Money was trying to show

19. Evaluation: Money 1975 The outcome was contrary to what Money expected- provides good evidence to support the role of genetic/biological factors in influencing gender roles Ethically the negative impacts of the decision were enormous (suicides) The strength was the ability to compare the behaviour of the identical twins in relation to how they were raised (boy-girl)

20. Raine et al. (1997) brain differences Aim: ▫to study whether violent offenders (41) had different brain structures compared to normal controls Procedure: ▫Used PET scans to compare brain function ▫Offenders were matched with group of non- offenders on age, sex and schizophrenia

21. Results Murderers showed lower levels of activity in the pre-frontal cortex, corpus callosum and parts of the limbic system ▫These are areas associated with self-control and inhibition Lower activity in the parietal cortex ▫Link to low verbal ability- lower educational attainment

22. Evaluation: Rainer et al PET scans are objective measures but difficult to interpret accurately Are the differences the only factors in creating criminal behaviour? ▫What about social factors Sample size large and it was a matched control group

23. Brain Lateralisation

24. Refers to the extent to which each hemisphere of the brain is involved in different activities ▫Some evidence shows that female brains  have less lateralisation for language abilities than males  Have less lateralisation for spatial tasks In stroke patients that affect only one hemisphere females are better off because of the bilateral activity

25. Assignment Create a list of the main physical, psychological and biological differences between males and females and work out if they are the result of genetic, hormonal or brain differences between the two sexes