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The Biological Perspective: Aggression and Free Will

The Biological Perspective: Aggression and Free Will. Learning Objectives. Objectives Identify some issues with explaining aggressive behaviour in a purely biological way Differentiate between the social psychological theories of aggression and the biological perspective

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The Biological Perspective: Aggression and Free Will

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  1. The Biological Perspective: Aggression and Free Will

  2. Learning Objectives • Objectives • Identify some issues with explaining aggressive behaviour in a purely biological way • Differentiate between the social psychological theories of aggression and the biological perspective • Describe the main assumptions of the biological perspective • Outline some of the biological factors that may be involved in aggressive behaviour • Discuss the issue of free will in relation to biological perspectives on aggression

  3. Is Aggression Part of Human Nature? • Since the end of World War II there have been about 30 days on which a war was not taking place somewhere on the planet. • Other animals with which we share a common ancestry, such as chimpanzees, have also been observed to engage in intergroup aggression that looks a great deal like warfare. • we talk about ourselves as if we had the capacity to choose our actions: free will.

  4. Free Will, Moral Responsibility and Psychology • actus reus – the guilty act • mens rea – the guilty mind. • In other words, in law, moral responsibility is generally predicated on intent.

  5. most psychological perspectives deny the existence of free will • behaviourists believe that our behaviour is determined by our conditioning and history of reinforcement. • Freudians believe that our behaviour is determined by unconscious processes. • The biological approach is deterministic in a similar way.

  6. Genetics and the possibility that certain behavioural tendencies are inherited. • The nervous system, and the way that certain behaviours are linked to the functioning of particular parts of the brain. • Chemical influences, and the way that substances such as neurotransmitters and hormones (and their analogues, drugs and toxins) can alter the functioning of the brain. • What these have in common is that they are governed by physical processes that follow the laws of physics.

  7. This type of deterministic and reductionist view precludes the idea of choice or agency and, consequently, makes the idea of moral responsibility irrelevant. • However society as a whole (psychologists included) carry on as if people do make choices about their actions and can be held responsible for the consequences

  8. However!! • there are circumstances where we (and the law) accept that biological processes have overridden ‘free will’, and that a person should not be held liable for the consequences of their actions.

  9. Case 1 – Dawn • Discussion question: what immediate assumptions might we make about Dawn’s behaviour? If Dawn had stabbed her husband, would we hold her responsible?

  10. Dawn contintued • Dawn is diabetic. Under some circumstances, her blood-glucose level can drop dangerously low, and she becomes hypoglycaemic. • Dawn’s blood-glucose level drops, her cerebral cortex, the part of the brain responsible for planning, reasoning and ‘rational’ behaviour starts to shut down. However, her limbic system, a more primitive part of the brain involved with responding to threats and aggressive behaviour, carries on functioning. Its aggressive impulses can no longer be controlled by the cerebral cortex.

  11. Cases 2 and 3 – Arthur and Colin • Discussion question: if someone claims to have committed a criminal act, such as homicide, whilst asleep, is it our first instinct to believe them? How could we test their claim?

  12. Frontal cortex (thinking, planning, rational behaviour) is inhibited whilst the person sleeps. • At times, sensory and motor cortex (areas associated with movement and sensation) are highly stimulated, leading to the experience of dreaming. • The limbic system (emotion) is often activated whilst we dream. • The pons paralyses us to stop us from acting out our dreams.

  13. Psychologists who examined both Arthur and Colin agreed that both were suffering from sleep disorders. In Arthur’s case, he suffers from night terrors. In this disorder, people tend to have very strong negative emotions whilst asleep, on which they are inclined to act. • They may lash out in their sleep and are sometimes violent, but often have no recollection of this when they wake up. In Colin’s case, it was decided that he was suffering from REMbehaviour disorder. This is rarer and often more dangerous than night terrors.

  14. A Patient came to a local sleep laboratory because he was keeping his family awake all night with shouting and acting out his dreams. His wife was forced to sleep in a different room not only so she could get some sleep, but also because she feared for her own safety. The patient managed to fall out of bed on a nightly basis, often injuring himself in the process. He was a war veteran and would often dream he was trying to avoid enemy attack. Thinking that it would help, he purchased a hospital bed with railings. Still he managed to climb out over top of the railings and fall to the floor. The patient then had to resort to sleeping on a mattress on the floor. When he was monitored in the sleep lab during overnight testing, and he entered REM sleep, muscle tone activity was detected when it should have been absent. Talking, laughing, shouting, flailing of the arms and kicking of the legs were all observed. He nearly fell head first out of the bed on several occasions. The patient has been prescribed a medication which will make his muscles relax during REM sleep so that he will no longer act out his dreams. To update, the patient is now doing fine and is sleeping in his own bed again. (Orr, 2003)

  15. Case 4 – David • Discussion question: how significant is it that David was reported to be acting ‘out of character’ in the days immediately prior to the murder?

  16. At his trial, David’s defence argued that his behaviour had not been under his control. Shortly before his behaviour changed, David had accidentally been exposed to a high concentration of an organophosphate pesticide called carbaryl.

  17. Case 5 – Sandie • Discussion question: do we view violent women differently to violent men?

  18. Whilst examining her history when preparing her defence, her defence team noticed that her violent outbursts seemed to occur at regular monthly intervals. • Discussion question: psychologists are divided on the question of whether pre-menstrual syndrome is a useful construct. Apart from the ambiguous nature of some of the evidence, some have argued that it paints a picture of women as ‘inherently pathological entities’ who are slaves to their biology. What do you think of this view

  19. Your task • Aggression is an area where the theories which have been put forward form a nature - nurture debate. Some theorists think that aggression is something which we all have, instinctively, and which we need to release; while others consider it as something which arises as a result of environmental circumstances. Based on your understanding of the topic so far, complete the task below: • Write a 300 word discussion on how aggression can be seen as a product of both ‘nature’ and ‘nurture’. There may well be sections in your text book to help you.

  20. Lesson Objective • Describe and evaluate how neural (e.g. neurotransmitters) and hormonal (e.g. testosterone) ‘mechanisms’ influence aggressive behaviour.

  21. The role of testosterone (hormonal) • This focuses on biochemical influences on aggressive behaviour. • Testosterone has been shown to be correlated with outward displays of human and non-human animal aggression

  22. Nelson (1995) reviewed research into how hormones influence aggressive behaviour. • Activity: Why has much of the research on hormonal influences on aggressive behaviour been done on animals?

  23. During puberty aggression increases when androgen levels are higher (especially in males). Animal research further supports these conclusions.

  24. Wagner et al (1979) show that if a male mouse is castrated, overall levels of aggression tend to reduce. If the castrated mouse receives testosterone aggression levels increase. • Activity: Give 2 problems with this research: • 1. • 2.

  25. Simpson (2001) argues that ‘testosterone is only one of a myriad of factors that influence aggression and the effects of environmental stimuli have at times been found to correlate more strongly’.

  26. This ignores the potential for individual difference. Harisson et al (2000)

  27. Testosterone does have a role to play in this complex formula of human aggression. Huston et al (2007) • The Basal Model of Testosterone is a model which suggests that an individual’s level of testosterone influences their level of dominance.

  28. Mazur and Booth (1998) who, after reviewing a number of studies in this field, concluded that men with higher levels of testosterone ‘are more likely to divorce, or remain single, be arrested for offences other than traffic violations; to buy or sell stolen property; to incur debts; and to use weapons in fights’.

  29. . The Reciprocal Model of Testosterone, suggests that testosterone levels vary with the person’s dominance. The level of testosterone is the effect of, and not the cause of, the dominance.

  30. Q// how might testosterone exert its hormonal and behavioural effects?

  31. There are three possible explanations for the testosterone-aggression relationship: • Testosterone causes aggression. • Aggression increases testosterone secretion. • Neither has an effect on the other.

  32. So, it is the aggressive behaviour which appears to drive the testosterone levels, not the other way round (i.e. behaviour-regulating hormone hypothesis).

  33. Kleinesmith et al (2006) showed how testosterone levels change as a result of behaving aggressively. • . There were two conditions: • Half the Pp had to dismantle and reassemble a pellet gun, which looked like a Desert Automatic handgun. • The other half were given the board game Mouse Trap to assemble.

  34. The conclusion from this study was that environmental stimuli such as guns may increase aggressiveness partially via increases in the hormone testosterone. • Activity: Give two strengths and two weaknesses s of this study: • 1. • 2. • 3. • 4.

  35. Another fascinating argument involves the ‘middle-ranking monkey’ study. Sapolsky (1997)

  36. It seems that testosterone doesn’t cause aggression, but it may exaggerate the aggression that is already there as a result of other factors.

  37. Role of serotonin (neural) • Serotonin is a neurotransmitter and research suggests that this chemical influences aggressive and violent behaviour. • Davidson et al (2000) suggested that serotonin may provide an inhibitory function so that when comparing violent criminals to non-violent ones, the levels of serotonin found in violent criminals were markedly lower.

  38. Serotonin has effects all over the body. It would seem that ‘low levels of serotonin in the brain can result in impulsive behaviour, aggression, overeating , depression, alcohol abuse and violent suicide’ (Lenard, 2008).

  39. Linnoila and Virkkunen (1992) who reported that low levels of serotonin are linked to ‘impulsivity and explosive acts of violence’. In some clinical trials, tryptophan and Desyrel 5HTP (a serotonergic drug) has been given to juvenile delinquents to reduce their aggressive tendencies (Morand et al, 1983).

  40. Caution must still be used before attributing the cause of aggression to serotonin levels.

  41. Brain structure and aggression • Certain areas of the brain are associated with aggression. In particular, the hypothalamus and amygdale

  42. the 1960s, Flynn found that stimulating the lateral hypothalamus in cats made them more likely to show ‘predatorial aggression, but when the medial hypothalamus was stimulated ‘vicious attack behaviour’ was more likely.

  43. Amongst humans, if an amygdalectomy (removal of the amygdala) is carried out, it reduces violent behaviour but at the cost of losing emotion!

  44. Activity: Use the your text books and the internet to investigate what happened to Phineas Gage and write in your own words: • 1. What happened to Phineas Gage? • 2. Critically evaluate whether this case study provided support for the argument that brain structure influences aggression (make sure you explain your answer).

  45. The role of genetics in aggression • While most people have 46 chromosomes (23 from each parent), it is possible for a male to have an extra Y chromosome, making them XYY. This XYY genotype has in the past been correlated with aggression (Court-Brown, 1965-67).

  46. The evidence to date does not conclusively show that this XYY variation does cause increased aggressiveness in males.

  47. According to Sapolsky (1997), genes are the ‘hand behind the scenes’, directing testosterone actions. • 1. Genes determine how much testosterone or oestrogen is produced and how quickly it circulates around the body. • 2. Genes determine the synthesis of testosterone receptors, and how many and how sensitive such receptors are. • 3. Genes control our behaviour via the messenger testosterone.

  48. Scientists became interested in a gene called monoamine oxidase A (MAOA) when they discovered by chance in 1995 that mice that lacked it suffered serious anger management problems. • The same gene had previously been implicated in human aggression when it was found that members of a Dutch family whose men suffered from excessive bouts of aggression carried a rare MAOA gene mutation (Cases et al, 1995).

  49. One way to study the possible genetic influence on aggression is to use twin studies. • Berkowitz (1993) reports that studies in the 1930s using these methods found an average concordance rate of 75% for MZ twins and 24% for DZ twins. This suggests that genetics do influence crime rates, including aggression but does not rule out environmental factors.

  50. A useful way to determine the role of genetics in aggression and rule out environmental factors is Adoption studies.

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