BIOLOGICAL APPRAOCH

GENESThe biological explanations of aggression say that aggression is caused by differences in the biological make-up of individuals. One example of these biological differences that could cause aggression is genetic factors. We are unsure of why there may be a link

between genetics and aggression; however research has found a correlation

■ Twin Studies – Monozygotic (MZ) twins share all of their genetic information whilst dizygotic twins (DZ) share 50%. If MZ twins are more alike in terms of aggressive behaviour than DZ twins, then this should be due to genes rather than environment. It is much harder to study aggressive behaviour than criminal behaviour, so few studies have tried to measure aggressive behaviour directly. However, Coccaro did use twins to study aggressive behaviour and found that 50% of the aggression towards to each other could be attributed to genetic factors

■ Twin studies provide geneticists with a kind of natural experiment in which the behavioural likeness of identical twins (whose genetic relatedness is 1.0) can be compared with the resemblance of dizygotic twins (whose genetic relatedness is 0.5).

■ In other words, if heredity (i.e. genetics) affects a given trait or behaviour, then identical twins should show a greater similarity for that trait compared to fraternal (non-identical) twins.

■ There are two types of twins:■ Monozygotic = identical twins (share 100% genetic information).■ Dizygotic = non-identical twins (share 50% genetic information, similar to siblings).

■ Research using twin studies looks for the degree of concordance (or similarity) between identical and fraternal (i.e. non-identical) twins. Twins are concordant for a trait if both or neither of the twins exhibits the trait. Twins are said to be disconcordant for a trait if one shows it and the other does not.

■ Identical twins have the same genetic make-up, and fraternal twins have just 50 per cent of genes in common. Thus, if concordance rates (which can range from 0 to 100) are significantly higher for identical twins than for fraternal twins, then this is evidence that genetics play an important role in the expression of that particular behaviour.

■ Bouchard and McGue (1981) conducted a review of 111 worldwide studies which compared the IQ of family members. The correlation figures below represent the average degree of similarity between the two people (the higher the similarity the more similar the IQ scores).

■ Identical twins raised together = .86 (correlation).■ Identical twins raised apart = .72■ Non-identical twins reared together = .60■ Siblings reared together = .47■ Siblings reared apart = .24■ Cousins = .15■ However, there are methodological flaws which reduce the validity of twin studies. For example,

Bouchard and McGue included many poorly performed and biased studies in their meta-analysis. Also, studies comparing the behavior of twin raised apart have been criticized as the twins often share similar environments and are sometimes raised by non-parental family member.

■ Adoption studies – One problem when studying twins is that twins will often be brought up together in a similar way, so it is hard to say whether the concordance rates are caused by genetic or environmental factors. To solve this problem psychologists can carry out adoption studies where they observe the levels of aggressive behaviour in adopted children and their biological parents. If there is a high correlation between aggression levels of the two you can say it is genetics not the environment that caused this aggression. Hutchings and Mednick (1975) studied 14,000 adopted children and found that a high proportion of boys with criminal convictions had biological parents with criminal convictions too, suggesting a link between aggression and genetics.

■ Genetic explanation for aggression■ MAOA – The gene MAOA is responsible for the regulation of serotonin

in the brain. Low levels of serotonin are thought to lead to aggressive behaviour, so a problem with MAOA could lead to aggressive behaviour. Brunner (1993) found that in a Dutch family with a history of serious aggressive crime the men had abnormally low levels of MAOA, supporting this explanation

■ Gene-environment interaction – This explanation says that it isn’t just genetics that causes aggression, it is a combination of the genetics and the environment that someone lives in that causes aggression. For example a study found that in a sample of children who had low levels of MAOA it was only the children who were maltreated that displayed antisocial behaviour

■ Physiology: how the nervous system and hormones work, how the brain functions, how changes in structure and/or function can affect behavior. For example, we could ask how prescribed drugs to treat depression affect behavior through their interaction with the nervous system.

■ ■ Genes and Serotonin

■ It has been suggested that males with an extra Y chromosome were predisposed to violent crime. Individuals with an XYY chromosome arrangements are above average height and below average intelligence. It might be the low intelligence that accounts for their over representation in prison populations. It has also been argued amongst twins that there's a 52% concordance rate in criminality between identical twins, suggesting that criminality is genetically transmitted.

■ Serotonin is a neurotransmitter that is believed to play an important role in the regulation of anger and aggression; lower than normal levels can lead to depression. Serotonin is also involved in the regulating and inhibiting appropriate behaviours, it is also know as the 'feel good' chemical. The study below examines the effect of an imbalance of a particular enzyme MAOA can have on serotonin levels and the effect this may have on behaviour.

■ Brunner

■ Genes and Serotonin

■ Aim: To document a family from the Netherlands where 5 males exhibited impulsive aggression and borderline mental retardation.

■ Sample: 5 males from one family, studied due to violent, impulsive aggressive tendencies These males have been involved in a range of crimes such as arson, attempted rape and exhibitionism.

■ Procedure: Data was collected from the analysis of urine samples over a 24 hour period.■ Findings:

■ Test showed a deficit in the MAOA enzyme■ In each of the 5 males, there was a point mutation on the x-chromosome of the gene responsible

for the production of MAOA, which in turn is responsible for the production of serotonin.

■ Conclusion: Impaired serotonin levels is likely to be responsible for the mental retardation and this could be linked with aggressive behaviour and inability for self control.

■ Evaluation:

STUDY OF THE BRAIN

Studying the brain

■ It is important to appreciate that the human brain is an extremely complicated piece of biological machinery. Scientists have only just “scratched the surface” of understanding the many functions of the workings of the human brain. The brain can influence many types of behavior.

■ In addition to studying brain damaged patients we can find out about the working of the brain in three other ways

■ 1. Neuro Surgery■ We know so little about the brain and its functions are so closely

integrated that brain surgery is usually only attempted as a last resort. H.M. suffered such devastating epileptic fits that in the end a surgical technique that had never been used before was tried out.

■ This technique cured his epilepsy, but in the process the hippocampus had to be removed (this is part of the limbic system in the middle of the brain.) Afterwards H.M. was left with severe anterograde amnesia. I.e. He could remember what happened to him in his life up to when he had the operation but he couldn’t remember anything new. So now we know the hippocampus is involved in memory

■ 2. Electroencrphalograms (EEGs)■ This is a way of recording the electrical activity of the brain (It doesn’t

hurt and it isn’t dangerous!). Electrodes are attached to the scalp and brain waves can be traced. EEGs have been used to study sleep and it has been found that during a typical night’s sleep, we go through a series of stages marked by different patterns of brain wave.

■ One of these stages is known as REM sleep (Rapid Eye Movement sleep). During this our brain waves begin to resemble those of our waking state (though we are still fast asleep) and it seems that this is when we dream (whether we remember it or not).

■ 3. Brain Scans■ More recently methods of studying the brain have been developed using

various types of scanning equipment hooked up to powerful computers. The CAT scan (Computerised Axial Tomography) is a moving X-ray beam which takes “pictures” from different angles around the head and can be used to build up a 3-dimensional image of which areas of the brain are damaged.

■ Even more sophisticated is the PET scan (Positron Emission Tomography) which uses a radioactive marker as a way of studying the brain at work. The procedure is based on the principle that the brain requires energy to function and that the regions more involved in the performance of a task will use up more energy. What the scan therefore enables researchers to do is to provide ongoing pictures of the brain as it engages in a mental activity.

■ These (and other) methods for producing images of brain structure and functioning have been extensively used to study language and PET scans in particular are producing evidence that suggests that the Wernicke-Gerschwind model may not after all be the answer to the question of how language is possible.

Key Features Methodology

•Natural Selection / Evolution•Adaptation

•Heredity / Genetics•Nomothetic (studies the group)•Reductionist•Instincts / Sociobiology•Comparative Psychology

•Lab Experiments•Correlation•Twin research•Naturalistic observations (Kettlewell)•Ethical Considerations•Reliability and validity of research

Basic Assumptions Areas of Application

•Psychology should be seen as a science

, to be studied in a scientific manner (usually in a laboratory).•Behavior can be largely explained in terms of biology (e.g. genes/hormones).•Human genes have evolved over millions of years to adapt behavior to the environment. Therefore, most behavior will have an adaptive / evolutionary purpose.

•Gender Role Development•Abnormal Psychology•IQ•Relationships•Medical Model•Stress Response (SRRS,stress immune system)

Strengths Limitations

•Very Scientific•Highly application to other areas: Biology + Cog = Evolutionary Psy•Helped develop comparative psychology•Strong counter argument to the nurture side of the debate•Many empirical studies to support theories

•Experiments – Low Ecological Validity•Humanism: too deterministic – little room for free-will•Doesn’t recognize cognitive processes•Reductionist•Bio psychological theories often over-simplify the huge complexity of physical systems and their interaction with the environment.

■ Key assumptions of the biological approach:■ The brain and the mind are identical■ Biochemical imbalances can affect behaviour■ Brain physiology can affect behaviour■ Behaviour can be inherited (as it is determined by genetic information)■ Evolution and the genetic basis of behaviour■ Charles Darwin’s publication – On the Origin of Species (1859) – described

the process ofnatural selection; characteristics that are not suited to a species’ environment will die out as it struggles to survive, and with time will evolve over generations so that only adaptivecharacteristics remain in future offspring.

■ Genes are the genetic information carried by DNA in chromosomes, found within a cell’s nucleus; they are passed on through generations of a species if individuals survive and successfully reproduce. In line with Darwin’s theory of evolution, it might also follow that genes form a basis of behaviour, as both behaviour and genes appear to be heritable. An example might be aggressive behaviour, in light of obvious survival benefits such as warding off predators and competing for resources.

■ Nature-nurture debate■ The genotype describes the genetic configuration of an individual, whereas phenotypedescribes

the combined effects of genetic makeup and surrounding environment on behaviour. The nature-nurture debate highlights a key argument in psychology, over the relative influence of biology and environment on the characteristics of an individual; an extreme biological approach assumes that these are determined solely by nature.

■ Effects of brain physiology and neurochemistry■ Interactions between regions of the brain help to control different functions, which biological

psychologists assume to be significant in determining our actions. For instance, the occipital lobe is involved heavily in processing sight, along with the frontal lobe, which is thought to be involved in control and attention.

■ Electrical impulses enable an important means of internal communication that directs our behaviour, travelling around the brain and to/from the body via the nervous system. Impulses are transmitted between neurons (nerves) at synapses, junctions whereneurotransmitters are released that inhibit or excite other neurons to achieve different responses. Neurochemical imbalances in the brain are often associated with abnormal behaviour – for instance, evidence suggests that imbalances of dopamine (a neurochemical linked with the brain’s natural ‘pleasure’ system) are associated with mood disorders such as depression.

■ The endocrine system is a slower-acting communication system that regulates the circulation of hormones, released by glands into the bloodstream. For example, cortisol and adrenaline are key hormones that facilitate the fight or flight response, a key evolutionary survival mechanism whereby the body primes itself for imminent danger (e.g. increasing heart rate, initiating sweating to cool down, dilation of pupils, sharpened sense of hearing).

■ Research methods used by the biological approach■ Animal studies – used to investigate biological mechanisms that govern human behaviour,

often where ethical guidelines would not allow human participation. Many species (e.g. rats) are thought to have a similar biological makeup to humans, such that studies’ conclusions can be generalised to humans. However, this methodology still raises ethical debate, and some argue that complex human behaviour cannot be replicated in non-human animals like rats, and thus cannot be investigated.

■ Case studies – can investigate normal behaviour by observing behavioural abnormality alongside corresponding changes in biology. A very early example is the apparent personality alteration observed in Phineas Gage (mid 1800s) after a railroad construction accident drastically changed his physiology by forcing an iron rod through his brain’s frontal lobe.

■ Drug therapy – behaviour can be manipulated by altering an individual’s biochemistry, a research method that can ultimately lead to developing drug applications to improve health and wellbeing. Initial phases of research are usually conducted on non-humans.

■ Scans – physiology and activity across the brain can be gauged using various techniques (e.g. MRI, PET, CAT), helping researchers to identify the functions of specific regions (known as localisation of cortical function).

■ Twin/family studies are useful for investigating the heritability of behaviour. For instance, research can investigate the likelihood that both of two twins develop a characteristic, known as a concordance rate. However, these studies can be time-consuming, due to long delays often required before follow-up data is collected. It is also difficult finding a large samples of participants for twin studies.

■ Example: Evidence has suggested that if one identical twin (monozygotic [MZ], with near-identical genetic information to the other) develops schizophrenia, there is a roughly 48% chance of the other also developing schizophrenia, whereas this is only about 17% with non-identical twins (dizygotic [DZ], who share about 50% of their genes). Such findings support that genetics play a significant part in the disorder.

■ Evaluation of the biological approach■ Strengths■ - Scanning research techniques are useful for investigating the functions

of the brain: an organ with obvious involvement in our behaviour that would otherwise be unobservable.

■ - The approach presents the strong nature viewpoint of the nature-nurture debate.

■ - The experimental methods used (gathering empirical [i.e. observable] evidence) make this approach very scientific.

■ Weaknesses■ - The approach is considered reductionist; complex behaviour, thoughts

and emotions are all equally explained by low-level biological mechanisms such as biochemicals and nerve impulses.

■ - Biology alone has been unable to explain the phenomenon of consciousness.

■ - An extreme biological approach does not account for the wide base of evidence that points to the influence of our environment (e.g. culture and society).

Nature vs nurture

■ http://www.simplypsychology.org/naturevsnurture.html

■ Nature■ Physiological/Biological. Psychologists taking this approach believe that behaviour can

be explained via innate influences such as hormones and genetic influences■ Psychoanalysis - Psychologists taking this approach believe that behaviour is controlled

by the innate aggression and sex drives. They do recognise that society restricts these drives and that these drives are controlled via the ego and the supergo

■ Nurture

■ Behaviourism - Behaviourists believe that human behaviour is learnt■ Humanism - This area of psychology explores the impact of a wide range of social and

environmental influences on human behaviour.■ Developmental - Psychologists looking at development have explored many

developmental factors, such as child rearing practices and the influence of role models, all of which have shaped human behaviour.

■ Social - Social psychologists have identified the profound influence of other people and social phenomena such as conformity and group behaviour on our behaviour.

■ An Interaction between Nature and Nurture■ Cognitive - Cognitive psychology looks at innate cognitive abilities, but recognises that

experience shapes these abilities.

Ethological theory

NEUROSCIENCE