Biological Psychology

What is Biological Psychology?

• Examines in detail the structure and function of the brain, how drugs affect transmission, etc.
• Mainly focuses on genes and characteristics that have been inherited and how the brain works

Aspects

• Neuron transmission
• Role of evolution in aggression
• Role of hormones in aggression
• Brain structure and functioning

Central Nervous System (CNS)- brain and spinal cord

Neurotrasmitters

• GABA: inhibitor to block messages, calm nerves and to give relaxation; low levels= anxiety/epilepsy
• Dopamine: pleasure feelings/addiction
• Glutamate: memory, learning, brain development. Too much= stroke/death
• Serotonin: happiness, good mood and wakefulness. Low levels= depression/anxiety- SSRIs prescribed for depression, OCD, etc. Affected by light and exercise

Glial Cells

- seem to have a role in clearing neurotransmitters away from synaptic gap

- wrap around fibres to form a myelin sheath

Parts of neurons

• Dendrites: finger-like structures surrounding a cell body
• Cell body: found at one end of a neuron, contains the nucleus
• Axon hillock: connects cell body to the axon
• Axon: long extension from the axon hillock to the axon terminal. Most of the axon is protected by myelin sheaths apart from where there are gaps: these are the nodes of Ranvier
• The myelin sheath contains Schwann's cells
• The axon terminal branches off: at the end of these branches are terminal buttons
• The buttons contain tiny sacs called vesicles that store neurotransmitters

Synapse: gap between the axon terminal of one neuron and the dendrites of another

When an action potential reaches the terminal, calcium channels will flood the synapse with calcium ions

Vesicles containing neurotransmitter ssubstance will then be released and travel to the outer membrane of the terminal button- the casing of the vesicle will fuse with the membrane, allowing the neurotransmitter to be released into the synaptic gap

If the neurotransmitters released from the terminal fit the receptors at the dendrites, the message is passed on. If not, the message is blocked.

Action Potential

• The way that the nerve impulse passes down the axon to stimulate the release of neurotransmitters
• Neurons have a resting membrane potential of -70mV- inside of neuron has slight negative charge in relation to outside
• A chemical message can either stimulate an excitory postsynaptic potential (which slightly depolarises the neuron and reduces the charge) or inhibitory (hyperpolarises and increases the charge)
• Enough excitory messages (at least, more excitory than inhibitory) causes positively charged particles to enter and triggers the action potential. The charge is normally around -55mV when this happens

Reuptake

• Regulates the amount of neurotransmitters in the synapse and recycles neurotransmitters
• Reuptake inhibitors stop the neurotransmitters being reabsorbed into presynpatic neuron so the message continues for longer

Nicotine

Mimics neurotransmitters and binds to niconic receptors, which causes an impulse and an ction potential, releasing dopamine

Decrease in dopamine receptors and change in shape of cell

More dopamine required to stimulate postsynaptic neuron to 'normal' level- desensitisation and leads to addiction

Cannabis

Binds to cannabinoid receptors, blocking activity and causing less activity in neurons

Removes inihibition from GABA neurons, which in turn removes inhibiton from dopamine neurons. This release of excess dopamine gives the 'high'

Cannabis taking affects blood flow and reduces the amount of oxygen going to the brain. Effects of this includes reduced attention and memory loss.

Four lobes: prefrontal, parietal, occipital, temporal

Damage to the prefrontal lobe has been associated with aggression

Bilateral- two halves, joined by the corpus callosum

The assumption that brain damage tells us brain function

When researchers find an example of brain damage, be it natural, medical or accidental, they study any problems with functioning in that individual and assume that the problems are caused by the damage to that part of the brain

However, it may be that it is other damage that causes the malfunctioning, not the one that the researchers are focusing on and it is possible that how we study the brain isn't sophisticated and precise enough to draw such conclusions

Prefrontal cortex/lobe

The prefrontal cortex is about regulating emotion (e.g. it's implicated in depression and connected with dopamine, serotonin, etc.): damage may mean that an individual cannot control aggressive reactions

Damage may also mean that the prefrontal cortex cannot inhibit messages from the amygdala

Limbic System

Role in self-preservation. Controls response to emotions rather than thinking.

Structures within the limbic system inclue the hypothalamus (responsible for homeostasis within the body); hippocampus (has a role in taking short-term memory and converting it to long-term) and amygdala (is linked to violent behaviour) as a centre for identifying threat and the 'fight' response)

Evolution- how inherited characteristics in organisms change from generation to generation

Natural selection- some inherited characteristics aid survival of organisms so that they can reproduce but some characteristics do not aid survival and organisms with these characteristics do not survive to reproduce

Survival of the fittest- organisms that suit their environment will survive long enough to reproduce so their genes continue whereas organisms who are not suited will not survive so their genes will not continue.

Aggression in humans can be explained in terms of helping to aid survival: 

• A male could be aggressive to protect his female mate and their offspring
• A male could be aggressive to protect his relationship with a female so he knows that any potential offspring is definitely his
• Competition for limited resources such as food and shelter, the winners of which would survive to reproduce and pass their genes on
• Keep status within a group and be seen as stronger which reduces chances of being attacked and allows them, again, to pass their genes on

Strengths

• Large amount of evidence to support the theory e.g. Kettlewell's study on moths
• Scientific method is used in supporting research, giving it scientific credibility
• Widely accepted and important theory

Weaknesses

• Aggression could be as much as hindrance as a help by attracting predators and aggression in other humans. Using energy in aggressive behaviour means that they may not use all resources successfully and therefore not survive. This can be answered to some extent by kin selection theory (an organism may die, but their genes are passed on through the offspring that does not), but the fact that the human does not survive because of their aggression still stands
• Alternatives to evolution and natural selection include Dollard et al's frustration-aggression theory, where frustration and aggression is displaced onto someone or something else because it couldn't be shown in the actual context that arouses it. This explains seemingly inexplicable aggression, such as when someone turns on a total stranger- natural selection does not.

Chemical messengers of the body e.g. melatonin for sleeping; testosterone and oestrogen. Binds to receptor proteins in target cells and changes functions

Neurotramsitters vs hormones

• Hormones- longer distance can be travelled- released from the endocrine system and into the circulatory system; neurotransmitters- restricted to appropriate neurons
• Hormones- slowly (seconds, minutes, hours); neurotransmitters- quickly (milliseconds)
• Hormones- message varies in intensity; neurotransmitters- all or nothing

Dabbs et al

• levels of testosterone in 89 male prisoners in for violent and non-violent crimes
• 10/11 prisoners who committed violent crimes had high testosterone
• 9/11 chance of committing non-violent crimes for those with low testosterone
• High levels of testosterone = rated by peers as tough

Strengths

• studies that support hormones as an explanation for aggression use careful controls with scientific methods. They are therefore scientifically credible
• findings support each other, which implies reliability
• a link is found even between studies using humans and animals, each with different methods and measures- shows credibility and reliability

Weaknesses

• human studies use correlations- definite causal link can't be made e.g. is there another variable causing the stress and aggression, rather than one causing the other?
• reductionist- studies seperate hormones from other factors such as neurotransmitters and brain structure
• many studies use animals- issues with generalising from animals to humans
• animal studies often have unnatural environments, but it could be environments that cause the release of hormones that leads to aggression- studies therefore aren't ecologically valid

• We all go through 5 stages: oral, anal, phallic, latency and genital; unresolved conflicts during these stages affect the development of a stable adult personality
• Libido- sex drive; an energy in everybody that doesn't increase or decrease
• Conscious mind- thoughts and ideas that we are aware of, can manipulate and make decisions using them
• Preconscious mind- thoughts that we can be aware of and access but not being accessed in the conscious mind
• Unconscious mind- many thoughts, emotions and desires that we do not know about but can still guide our thinking and behaviour
• Eros- life instinct, self-preservation- induces arousal
• Thanatos- death instinct, reduces arousal
• Id- pleasure principle, 'I want', demanding
• Ego- reality principle, tries to balance id and superego
• Superego- conscience from parents and society, 'you can't have'

1) Main drives for aggression are libido and self-preservation

Ego represses unacceptable thoughts into the unconscious but these are displaced and reoccur in dreams, or towards someone else who is not the actual reason for them. In this sense, Freud originated the frustration-aggression hypothesis.

2) Aggression is an outlet for the death instinct, using biological drives

Catharsis is the venting of aggression, through watching other people being aggressive or taking part in aggressive activities, such as a sport. However, evidence is inconclusive e.g. Bandura found that watching aggression made children aggressive

Fromm- benign aggression- response to threat that diappears with said threat; destructive aggression- used to achieve own goals

Strengths

- vastly improved contemporary treatments for neuroses that would be considered barbaric in modern society e.g. trying to shake the madness out of a patient

- case studies used gathered valid data

Weaknesses

- data was valid, but qualitative and immensely personal- perhaps not suitable for generating a theory from

- sample of patients was not generalisable- high-class Venetian women (bar Little Hans, a little boy)- no scientific method, probably because Freud's concepts are not measurable- lack of scientific credibility

- case studies included some intepretation e.g. dream analysis- subjective and potentially biased, not objective

- his work span was limited, going up only to adolescence

Psychodynamic

• Internal structures is primarily the unconscious thoughts and desires
• Works on a model- a lot of our mind isn't accessible
• Lacks scientific credibility, hard to generalise and replicate
• Release of tension through catharsis

Biological

• Internal structures refers to brain structure and its functioning
• Works on 'reality' i.e. actual functioning and physical structures
• Scientific credibility, careful controls, brain scanning
• Release of tension through general release of stress

However:

• Evidence that a young child is all 'id'- child is thought to focus on right-brain, which works on emotions rather than rational thinking
• Psychodynamic can be said to focus on emotions whereas biological focuses on physical
• Limbic system and prefronal cotex perhaps link to analytical part of the conscious mind
• Brain stem and cerebellum link to unconscious

Twin studies compare monozygotic (MZ; identical) and dizygotic (DZ; non-identical) twins to see differences between MZ twins and the characteristic (e.g. schizophrenia, IQ, depression, personality, etc.) and DZ twins and the characteristic.

When both twins share a characterisic, there is a concordance rate (a perfect concordance rate is 1). If there are strong differences between MZ and DZ twins and MZ twins share characteristic more, characteristic is said to have, to an extent, a genetic basis.

Strengths

• No other way of having identical DNA- main way that influence of genes on behaviour can be studied
• Most twins share their environment and are treated like twins- minimises any environmental influences

Weaknesses

• MZ more likely to be treated like twins than DZ- MZ twins may share environment to more extent than DZ twins
• Need to take epigenetic modification into account. Epigenetic modification = how genes are switched off and on by the environment. Therefore, genes cannot be isolated and environment will always be a factor

Aim- look at genetic & environmental issues underlying the change of physical aggression (p.a.) from infancy to school age

Procedure- used 254 MZ & 413 DZ twins from Quebec Newborn Twin Study; information about p.a. collected by the Study at 19.6, 31.9 & 50.2 months; p.a. measured as in a questionnaire given to mothers- three items, 'hits, bites, kicks', 'fights', 'one attacks another'- they answered 'never (0)', 'sometimes (1)' 'often (2)'; shared and non-shared environment data also gathered

Result- MZ more similar than DZ in both their p.a. scores + the way they rise between ages (e.g. 0.68-0.72 MZ vs 0.32-0.47 DZ). Genes & n-s environment contributed, shared environment had small effect

Conclusion- at each age, genetic factors explained at least half of the variance in p.a.- the rest down to non-shared environment

Strengths- study uses repeated measures- no individual differences; good sample size and had a lot of information about them

Weaknesses- lack of validity- only gathered data from one person in one setting; might not be fair to assume that twins are brought up together

When children's envrionment is different to that of their biological parents, the issue of the environemnt is controlled for when looking at the effect of genes. If there any similarities between the child and their biological parents, it is likely to be because of genes, not the environment.

Strengths

• It is difficult to separate genes from environment any other way
• Studies can be longitudinal: developmental trends can be studied, so characteristics that come about as genes are triggered (e.g. schizophrenia), and linked to genetic influences

Weaknesses

• Adopting families are likely to be similar to one another, makes the environnment of the adopted child unique- perhaps ungeneralisable
• Adopted children tend to be placed in families similar to their own- biological and adopted environments not so different

Aim- investigate influence of familial relationships on genetic development

Procedure- 360 adoptive triads; focus on data which showed executive function (externalising); early literacy skills (academia) and cortisol (internalising)

Results- externalising behaviour is affected by environment

Conclusion- child's genes can interact with adoptive family's environment to produce behaviours

Strengths- large, generalisable sample; no confounding variables

Weaknesses- difficult to demonstrate cause-and-effect; genetic influence was inferred

Aim- to show  that the brains of murderers who pleaded not guilty by reasion of insanity (NGRI) were different to those of non-murderers

Procedure- 41 NGRIs and 41 controls- control group almost matched participants; each participant carried out a practice task, and then was injected with an FDG tracer; a continuous task was carried out which targeted the frontal lobes

Results- no differences in performance; NGRIs had lower glucose metabolism in the prefrontal lobe, parietal lobe, corpus callosum, left amygdala, left hippocampus and higher glucose metabolism in the occipital lobe, right amygdala, right hippocampus and right thalamus all in comparison to the controls

Conclusions- NGRIs have reduced glucose metabolism in the areas stated above, and abnormal activity with regard to symmetry in the two hemispheres; violence has a biological cause

Strengths

• The results of PET scanning can be interpreted objectively by more than one researcher- results tend to be reliable
• PET scanning is scientific because of the objectivity, replicability and controlling of the procedure
• The sample was the largest that had been used in a PET scan study up to that point- possible generalisations to other NGRIs

Weaknesses

• Findings probably aren't true of all violent offenders
• Findings describe differences but do not explain them e.g. could have been from birth or from, for example, a head injury in the environment
• Tracers had to be injected- somewhat invasive- not ethical

Aim- to study the contribution of genes and shared/non-shared envrionment to social and physical aggression 

Procedure- 234 6-year-old twin pairs from Quebec Newborn Twin Study; 409 classrooms used; written consent gained from parents of all the children; teachers completed behaviour questionnaires and rated behaviour using standardised scales, from which a score was derived; photos of all the children in a class were given to the twins' peers and they were told to circle three photographs with regard to behaviour e.g. circle the photographs of three children who 'hits, bites or kicks others'- score also derived

Results- MZ correlations nearly 2x as high as same-sex DZ for p.a. (genes); MZ and same-sex DZ correlations for s.a. similar (shared enrivonment more than genes)

Conclusion- 50-60% of differences in p.a. down to genes and the rest to n-s envrionment; 20% of differences in s.a. down to genes, 20% to shared environment and 60% to n-s environment; one-way directional effect- high levels of p.a. predict s.a. but not other way round

Strengths

• Different teachers and different peers rated the same child consistently- reliability
• Teacher and peer ratings mostly agreed- suggests reliability and a degree of validity
• Comparing MZ and DZ twins good way to look at weighting of genes and environment. Using same-sex DZ twins is useful for making the twin pairs as similar as possible except for shared genes

Weaknesses

• Ratings are not direct observations, so there may not be validity
• Assumptions have to made separating shared from non-shared environments, which reduces how scientific the study is
• Some twins were DNA checked to help identify them as MZ or DZ but others were not- incorrect allocation of twins may affect findings

What are the implications for society if aggression is found to be caused by nature not nurture?

Describe

• If aggression is caused by a trigger in the environment, an individual can choose not to behave in that way
• However, if aggression is caused by biology, the individual cannot really choose how they act and so perhaps should not be blamed- after all, we cannot help our biology
• A third view is that people have to learn to control the aggression, but not be blamed for the innate aggression itself
• Implication is that punishments aimed at preventing aggression, e.g. imprisonment, may not be ethical because a person is punished for  something they cannot help doing
• Seems unfair of society to treat one emotion (such as depression or anxiety) and punish another (such as anger or aggression)

• A review by Adelson found that aggression can be provoked in an animal if specific brain regions, e.g. hypothalamus, are electrically stimulated- aggression comes from brain functioning and is in our nature
• Dabbs et al found links between testosterone and activity in the aggression centre in the brain- hormones are implicated- part of our nature (however, stress hormones are triggered by environment- so maybe an individual has some control here by staying away from stressful situations)
• Raine et al found differences in glucose metabolism in parts of the brain- brain functioning, part of our nature
• Theory of natural selection- aggression is inherited- society should not blame someone for the genes they inherit and punishment wouldn't be useful
• Implication of aggression being in someone's nature is they need treatment (psychology as a form of social control) whereas if aggression is learned (nurture), operant conditioning can be used to unlearn it with punishments, which society will think is worthwhile
• Charles Whitman had a brain tumour pressing on his limbic system, which is generally seen as the reason why he killed many people in the US in 1966- tumour wasn't his fault so neither was the aggression