Biological Psychology Flashcards
Describe Role of Neuron
Neuron- Specialised cell for the purpose of communicating
Describe Components of Neuron
◦Cell body- Main part of cell, contains nucleus and mitochondria
○ The nucleus-Houses genetic material for cell
◦The mitochondria- Site of aerobic respiration where energy is released from glucose. Provides cells with energy
◦Dendrites branches at top end of neuron, attached to cell body and receives messages from other neurons to trigger action potential (Electrical impulse) within cell.
◦The axon long, branch extension of cell body, passes electrical impulse down to end of neuron to allow communication with other neurons .
◦The axon hillock axon hillock triggers nerve impulse and connects cell body to axon
◦The myelin sheath- Fatty deposit that surrounds and electrically insulates axon to help speed up message transmission rate, and allows for electrical nerve impulses to bce passed along. Insulates (Keeps in impulses)
◦The nodes of Ranvier breaks between cells along adjacent myelin sheath
◦The axon terminal and the axon terminal buttons-Axon terminals are at end of axon, at end of these are terminal buttons/boutons. Axon terminals pass nerve impulses from cell body to parts of the body they control/activate (Muscle, gland, Another neuron.)
○ Terminal buttons/Boutons- Very end of neuron where nerve impulse becomes a chemical message that can be passed to dendrite of other neuron
○ Vesicles- Tiny sacs that contain molecules of neurotransmitter chemicals
◦Neurotransmitters- Chemicals that passes messages between neurons
Describe what is meant by Action Potential
Beginning of one cell communicating with another, leads to synaptic transmission
Actual method by which nerve impulse travels down axon of neuron to stimulate release of neurotransmitters, tiny electrical impulse triggered by change of neuron’s electrical potential.
Describe the process of Action Potential
Neurons have resting membrane potential of about -70mV meaning that inside of neuron has slight negative charge in relation to outside. When neuron receives message from another neuron, this chemical message can either stimulate an excitatory postsynaptic potential (reducing neuron charge by depolarisation)where the sodium channels (S-, NEGATIVE CHARGE) play a role in generating the action potential in excitable cells and activating a transmission along the axon. Or Inhibitory postsynaptic potential (Increasing Neuron charge by hyperpolarisation). Potassium ions reach equilibrium when the membrane voltage is below -70 mV (Millivolts), so a period of hyperpolarization occurs while the K+ channels are open. Those K+ (POSITIVE CHARGE)channels are slightly delayed in closing, accounting for this short overshoot.
When neuron has received enough more excitatory messages that are sufficiently strong to reach neuron’s own threshold, action potential triggered (Impulse sent down axon via axon hillock), usually happens when neuron charge reaches approximately -55mV
POSITIVE=Inhibitory, Polarised, split between + and -, NEGATIVE=Excitatory, depolarisation, neutralisation, lower negative charge
How does Action Potential Work?
Starts at presynaptic neuron and axon hillock, electrical signals then jump through nodes of ranvier (Gaps in Mylein sheath) and passes faster due to insulation
What is Synaptic Transmission?
Cell’s electrical impulse/action potential starts as small electrical impulses generated at axon hillock, but once message reaches terminal button it turns into chemical message. When impulse reaches axon terminal, neuron can pass chemical message to further neurons across synaptic gap/cleft (space between two). Message sender= Presynaptic neuron, message receiver= Postsynaptic neuron
Each neuron is responsible for producing certain chemical/neurotransmitter, when the action potential reaches axon terminal, calcium channels will obey, flooding terminal buttons with calcium ions. Vesicles containing neurotransmitter substance will then be released and travel down to outer membrane of terminal button where vesicle casing will fuse with membrane and allow for neurotransmitter to be released from vesicle into synaptic cleft.
Receptors on postsynaptic neuron designed to bind to specific neurotransmitter and when detected, the neurotransmitter molecule will then be absorbed by postsynaptic neuron. Any neurotransmitter molecules not absorbed by receptors of postsynaptic neuron then will either diffuse away (be destroyed), or neurotransmitters will be absorbed again by presynaptic neuron (Reuptake) and they are recycled, ready to be fired again. Reabsorbed molecules will be destroyed by enzymes within neuron to “Turn off” neuron in preparation for future action potential.
Describe Effect of Drugs on Synaptic Transmission
Recreational drugs change function of neurotransmitters is brain, by preventing enzymes from breaking down dopamine neurotransmitter, leading to more dopamine being in synaptic cleft and going through reuptake via pre-synaptic neuron, this causes intense feeling of euphoria while dopamine remains. The body responds by down-regulating (reducing) the amount of dopamine naturally in body, and so eventually, when drug has worn off, less dopamine in brain then there was before.
natural activities make a smoother curve, dopamine level increases and decreases at lower difference
With drugs, spiking occurs (Euphoria), down-regulation of dopamine leads to severe drop of dopamine levels (Dysphoria)
Therefore, person becomes dependent on drug to take away negative feelings, (Dysphoria) and they also become tolerant (Meaning that more of the drug is needed to cause same feeling), leads to addiction.
Describe Effect of Brain Structure On Aggression
Midbrain-Contains an area called periaqueductal grey matter (PAG, area of grey matter within midbrain which plays a role in pain modulation and defensive behaviour) which links amygdala and hypothalamus with prefrontal cortex (Seen before in Phineas Gage). Has a role in co-ordinating and integrating behavioural responses to perceived internal and external stressors such as pain and threat , can be images, and sounds also (Detecting whether something is threatening). Regulating pain and external behaviour. Responses are co-ordinated in prefrontal cortex. Lesions to PAG in rats that have recently given birth (Protective) show increase in aggression when rats confronted with potential threat i.e. unfamiliar male rats (who may kill babies who are not there’s) in cage (Lonstein and Stern 1998).
Amygdala- linked to PAG, Centre for Emotions, emotional behaviour, motivation. Integrates internal and external stimuli, and every sensory modality has input, which when combined gives us an instinctive feeling/reaction to environment that will include aggression. Prefrontal cortex also connects to amygdala and may lead to expression of aggression. Prefrontal cortex weighs out pros and cons of expressing aggression.
Hypothalamus-Maintains homeostasis (Response which maintains human body in reaction to change in external conditions) through hormone regulation (Including sexual function), linked to aggressive behaviour in males via testosterone production.
Prefrontal cortex-Sits right behind forehead, at front of forehead governs behavioural regulation and social interaction (Is this acceptable, how am I going to look?) , delays gratification (Want for satisfaction), impulse control and has connections to amygdala and hypothalamus, damage normally results in problems with anger management, irritability, impulse control.
Frontal lobe aids in consideration of right and wrong
Evaluate Brain Structure and Aggression
- Support for the link between brain function/structure and aggression comes from human case studies i.e Phineas Gage whose social behaviour was largely affected by prefrontal cortex damage, from calm, well-mannered, social, to aggressive, irritable, and using profanity
- However, he’s a single case and unique, so effects of brain damage may not represent all humans (Idiographic- Focuses on specific person), although other case studies also support involvement of prefrontal cortex and relation to aggressive behaviour (Adds credibility)
- More specific support comes from Raine et al (1997) who used a sample of 41 murderers and found lower prefrontal cortex activity in PET scans
- Raine conducted research on Prisoners from New Mexico, and found that they had smaller amygdala (Responsible for emotions and emotional responses)
- Biological approach to explain aggression supports genetic basis because our genetic information determines are brain structure, therefore males are predisposed to be more aggression compared to females.
Explain Effect Of Evolution on Aggression
In evolutionary terms, success is measured by production of offspring that survive to reproductive maturity. In the EEA, successful males physically bigger and stronger so would be those most capable of providing of and protecting mates and offspring. Psychologically, males would have adaptive advantage as they were naturally more aggressive when resources were threatened.
Gave advantage of mate choice. Successful females chose mates who provided good genes, big, strong men favoured. Such men were also more likely to provide better resources in terms of food (Hunting and keeping food safe) and protection towards offspring and women against predators and other males who may kill wife or offspring, suggesting that those who displayed aggressive traits would be more successful than those who didn’t, competition for mates has driven masculine aggression.
Theory would also suggest that females would be less physically aggressive in EEA as it’d be an evolutionary disadvantage for females who’d spend long time-periods pregnant, breastfeeding, looking after vulnerable young children to ensure their survival and gathering foods such as fruit and berries. According to evolutionary psychology, this is why female aggression is more verbal/emotional instead of physical. Buss (1999) proposed that females would still be in competition for best mates but achieved victory by criticising other females to potential mates to make them appear less attractive. Hypothesis has been experimentally tested and found support.
If these ideas are valid, we may expect physical difference in brain structure/chemistry of males and females, which would lead to greater expression of aggression in males. We would also expect to see greater degree of aggression among males than among females and those animals to which we are more closely genetically related would show similar behaviour.
Evaluate Effect of Evolution and Aggression
Credibility- Strength of evolutionary theory is so that it can explain gender differences in aggression i.e. more co-operative females naturally selected as can protect self +Offspring. More aggressive males naturally selected due to better hunting and protection. Chimpanzee studies support gender differences/patterns in aggression, can be generalised to humans due to close genetic relation, increases credibility of idea (Manson + Wrangham 1991)
Objections- Some people reject evolutionary explanation of aggression (Natural Selection) , in favour of psychodynamic theory which suggests that gender differences in aggression may be determined by innate personality aspects, such as Id (Pleasure Principle, some males may find hurting others to be pleasurable) and Thanatos (Death + Destruction), males may be more destructive + Impulsive due to stronger Id and Thanatos in comparison to females who may have stronger Super Ego.
Differences- Theory doesn’t explain individual differences such as culture in aggressive behaviour, for example among the Kung San people of the Kalahari aggression is discouraged from childhood so is rare, in contrast, the Yanomami of Venezuela and Brazil have been described as fierce people , aggression is a socially acceptable behaviour to gain status in society (Wolfgang and Feracuti 1967)
Application- Theory has application to reproductive behaviour and human relationships (Buss 1999) found that, across 33 countries, males preferred younger, more attractive women and this enhances reproductive success due to more female fertility.
Ultimately, theory is credible due to research evidence (Manson and Wrangham) and high applicability (Reproductive behaviour), however is limited in credibility due to being objected by psychodynamic theory and not acknowledging effect of individual differences such as culture on aggression.
Explain effect of hormones on Aggression
Hormones are chemical messengers carried in the blood that travel around whole of body and affect long-term changes. Produced and excreted by glands, system of glands is called endocrine system.
Affect behaviour and cause physical changes in the body i.e., oxytocin is released by pituitary gland and increases trust between people.
Testosterone is an androgen (Develops or maintains male characteristics) and is more prominent in males.
Antenatal exposure to testosterone increases spatial ability and competitive aggression. There’s a critical period where testosterone sensitises neural circuits: Stimulates cell growth in areas of hypothalamus and amygdala (Naftoli, Garcia-Segura, Keefe 1990)
Supporting evidence comes from rodent research, male rodents castrated (Stops testosterone production by removing testicles and behaviour will be compared with control under aspects such as threat and competition for mates, castrated rodents show little-to-no aggression, however if testosterone injections are used, typical aggressive behaviour shown. Injecting neonatal female rodents with testosterone made them act much more aggressively when given testosterone as adults compared to control females (Edwards, 1968), supports the idea that testosterone is implicated in aggressive behaviour and sensitisation of neural circuitry after birth is an important factor in the effect of testosterone release.
Evaluate effect of hormones on Aggression=
Credibility- Idea has research credibility from testosterone research in females, James Dabbs and Marian Hargrove (1997) measured testosterone in saliva of 87, female prison inmates. Degree of criminal violence positively correlated with testosterone level, as well as testosterone levels also correlated with aggressive dominance within prison. Aggression-testosterone link also found in male prisoners in replications, increasing validity of association.
Objections- Objecting theories such as idea of brain structure effect on aggression suggests that brain damage such as prefrontal cortex and amygdala may result in increased aggression due to causing behaviours such as irritability, impulsivity, lack of self-control, brain structure idea has more credibility than Hormone idea as has generalisable, supporting research evidence such as Phineas Gage (1954) who suffered prefrontal cortex damage and became more aggressive.
Differences- Differences in hormone levels, species, morals with humans and animals such as rats may result in limited generalisability of research of animal studies to aggression, which can suggest that humans may be affected differently by hormones in terms of aggression.
Application- Understanding the effects of hormones on aggression could lead to real practical benefits, for example, if aggression is chemically controlled it should be possible to manufacture a drug that influences the hormonal mechanism and reduces aggressive behaviour preferably without widespread effects on bodily effects and behaviours. Anti-testosterone drugs may have positive consequences for individuals, communities and societies.
To conclude, idea of hormones and aggression is credible due to supporting research evidence from Hargrove (1997) and having high applicability to hormone-influencing drugs as method of reducing aggression, however has been objected by more credible brain structure explanation of aggression and, as the research primarily uses animals, doesn’t acknowledge the differences animals and humans have (Species, Morals, Hormone levels) and can suggest these differences limit generalisability of idea of hormones and aggression to humans
Explain Psychodynamic Theory of Aggression
Two innate drives (Eros and Thanatos) would come together to form first part of personality from birth-2 years (The ID). The unconscious ID is most primitive part of personality that’s completely driven by impulses of Eros and Thanatos with no thought for consequences. ID operates on pleasure principle, demanding immediate gratification of urges.
Around age 3-4+ , new aspect emerged, the ego (Part of personality that attempts to satisfy the id within restrictions of reality). This is driven by reality principle (Rule of what’s socially acceptable). The norms and rules of society are learned and, although the ego doesn’t understand right from wrong, it understands when it’s appropriate to show behaviours such as aggression. Satisfies ID urges indirectly and symbolically, has no moral sense, doesn’t try judge ID, but tries to direct and control all their urges.
At some time between ages 5-6+ , the third and final aspect of personality emerged (Superego) and this operates morality principle (Understanding what’s right from what’s wrong), delays ID urges until appropriate time and place and allows child to feel pride for acting correctly (The ego ideal) or feel guilty for inappropriate behaviour (The conscience). Aggressive impulses should be well controlled if superego is properly developed.
Any issues in development of ego or superego will result in problems managing urges of id and aggressive behaviour could be frequent, for most people, ego and superego are well developed so id urges remain in unconscious mind and we’re unaware of violent urges, however may be aware of them through catharsis behaviours (Love of violent films and/or boxing), Ego balances out superego (Restricts, ID and thinks about consequences of doing action for pleasure)
When Ego fails to balance out demands of ID and superego, psychological difficulties can occur, if people have strong ID, this means that impulsive/aggressive behaviour is likely to satisfy these urges. Usually, these urges are managed by the other components of the personality and therefore are in the unconscious. The only time we may be aware of them is when we engage in aggressive activities such as sports by watching violent films (Catharsis).
Evaluate Effect of Psychodynamic on Aggression
Credibility comes from: Stephanie Gorka et al. (2013) used MRI scans to study activity of pre-frontal cortex and the amygdala. Showed that alcohol interferes with the brain’s ability to pass information between the two. This also backs up Freud’s idea that one part of the psyche generates aggression, and another part decides what to do about it.
Objected by Albert Bandura in his 1961 study makes a big point of the fact that the children who observed the aggressive role models displayed more aggression themselves, not less. This goes against what catharsis would suggest.
Doesn’t acknowledge role of individual differences such as brain damage on three parts aspects of the personality, for example prefrontal cortex damage may result in impulsivity, does this mean that the Id has become more dominant over the superego?
Freud’s theory has applicability to everyday life, for example catharsis which may be seen in boxing, playing violent video games and has no effect on self, adds to credibility of theory.
To conclude, Psychodynamic explanation has high credibility from research evidence such as Gorka et al’s MRI scans and the high applicability of concepts i.e., Catharsis in playing violent video games however lacks credibility due to being objected by research evidence (Bandura 1961) and Lacks explanation into individual differences i.e. brain damage inti aspects of personality.
Explain Classic Study Raine et al 1997
Aim: To investigate if there is a difference in the structure of the brain activity between people who have committed murders (NGRI’s- Not Guilty for Reason of Insanity) and non-murderers
Experimental group- 41 criminals with convictions for murder/manslaughter who were being tested to gain evidence to support claim of NGRI. Of these six had schizophrenia, 23 had suffered organic brain damage/head injury, three were substance abusers, two had affective disorder, three suffered with hyperactivity and/or learning disability, two diagnosed with aggressive/paranoid personality disorder.
Control group matched with experimental group on age and gender. Screened for general health (Physical examination, medical history, psychiatric interview), participants excluded if they had history of seizures, substance misuse, head trauma, consent obtained from all participants before PET was administered.
All participants given continuous performance task (CPT) to complete. Sequence of blurred numbers to focus on. Participants started CPT as a practice trial 10 minutes before being injected with Flucodeoxyglucose (FDG). After 32 minutes on CPT, PET scan completed to measure metabolic rate in different brain areas to look at activity levels in areas. Medication-free 2 weeks prior to PET scan.
Results
*Brain dysfunction in NGRI group was in areas previously implicated with violent behaviour. Compared to control groups, murderers shown-
*Lower activity in prefrontal cortex (Lateral and medial areas)
*Higher activity in occipital lobe
*Identical activity in temporal lobe
*Subcortical Areas
*Lower activity in corpus callosum
Asymmetrical Amygdala, Medial Temporal lobe, and thalamus activity (All had lower activity in left side but higher activity in right side)
Conclusion
Brain differences associated with many behavioural changes that can be related to violent behaviour. For example, dysfunction in prefrontal cortex linked to impulsivity, lack of self-control, inability to learn from behavioural consequences. Hippocampus, amygdala, thalamus related to learning, suggests criminals unable to modify behaviour as they can’t learn from consequences of actions.
Evaluate Raine et al 1997 Classic Study
Aim- To investigate brain abnormalities and aggressive behaviour in murderers (NGRI)
Sample- Two groups of 41 people, 39 males, 2 females in each group.
Control group matched with experimental group on age and gender and ppts excluded if they had history of seizures, substance misuse, head trauma,
AO3- Sample is somewhat large (82 People) which was largest at time for study, results representative of wider population. The sample is androcentric, uneven balance of males and females in group, this is a limitation as results regarding brain and behaviour may be difficult to generalise to females.
Method 1- The study used PET scanning.- AO3- PET is an objective, brain-imaging technique which can be easily replicated, re-tested for reliability, however the interpretations of the PET may be subjective due to the unclear images/results which can lower reliability.
Method 2- Numerous situational/social factors and extraneous variables which may contribute to violent behaviour and/or brain dysfunction. Low red internal validity of results regarding effect of brain differences and violent behaviour. CPT used by Raine can be criticised for being artificial, including the idea of participants using unusual task in unusual mental state, which can lower ecological validity of study as it’s unrepresentative of everyday life. Extra- Experimental and Control group were matched on age and gender, this has the strength of there being a higher internal validity of the study as individual
Results-Brain dysfunction in NGRI group was in areas previously implicated with violent behaviour. Compared to control groups, murderers shown-Lower activity in prefrontal cortex (Lateral and medial areas).Higher activity in occipital lobe, Identical activity in temporal lobe, Asymmetrical Amygdala, Medial Temporal lobe, and thalamus activity (All had lower in left side but higher in right)
Conclusion-Brain differences associated with many behavioural changes that can be related to violent behaviour. For example, dysfunction in prefrontal cortex linked to impulsivity, lack of self-control, inability to learn from behavioural consequences. Hippocampus, amygdala, thalamus related to learning, suggests criminals unable to modify behaviour as they can’t learn from consequences of actions.
Application- Application to real life because it provides the idea of treating brain deficits to reduce aggression.
Explain Brengden et al 2005 Contemporary Study
Contemporary Study- Brengden Et al 2005
Aims- To see if social aggression could be caused by genes or environment.
To see if social aggression shared the same cause as physical aggression.
To see if one type of aggression leads to another type.
Sample- Recruited from Quebec Newborn Twin Study (QNTS) and all were pairs of twins born between November 1995-July 1998.
At start of study, 322 pairs of twins tested, complete data at all stages only collected on 234 pairs. Of these, 44 pairs MZ males, 50 MZ females, 41 DZ males, 32 DZ females and 67 pairs were mixed-sex DZ twins.
Procedure- Data from sample gathered longitudinally at 5, 18, 30, 48, 60 months and then again at age 6.
Data gathered consisted of two ratings of each twins behaviour- one by teacher, one by classmates. Ratings gathered in spring term of school year to ensure twins were well known by providing ratings of behaviour.
Teacher ratings based on agreement with serries of statements taken from items on preschool social behaviour scale (PSBS) and direct and indirect aggression scales (Bjorkqvist, Lagerspetz et al, 1992) such as ‘To what extent does child get into fights’ (Physical Aggression) and “To what extent does the child try to make others dislike a child” (Social Aggression). Scores given by teachers on 3-point scale (0=never, 1=sometimes, 2=often). Peer ratings of twins done by giving each child in twins’ class booklet containing photos of every child in classes. Every child then asked to circle three pictures of children that they thought matched four behaviour descriptions, for example “Tell others not to play with a child” (Social aggression), “Gets into fights” (Physical Aggression). Each twin given physical and social aggression score from teacher ratings.
Any peer selections on social or physical aggression descriptors that were made of each twin were also recorded.
Results- Initial findings from study suggested much higher correlation of ratings of MZ twin pairs on physical aggression than between same-sex DZ twin pairs.
This was the case in both teacher and peer rating scores for the twins. On the other hand, scores for social aggression were roughly, equally correlated in MZ and DZ twin pairs. Findings would suggest that, in relation to first aim, physical aggression will be caused by genetic factors, whereas social aggression may be better explained by shared environmental factors. In relation to second aim of study, correlation was found between physical and social aggression in children that was best explained by genes rather than the fact that twins shared same environment,
This could be result of aggressive tendencies in general being result of genetic factors, but tendencies may be expressed by result of environment factors such as exposure to other people’s aggressive behaviours. Finally, when looking at third aim of study, data suggested that physical aggression may lead to social aggression but not other way round. They concluded that perhaps expression of aggressive tendencies changes as children grow as they may learn more ‘Socially acceptable” ways to show aggression. As Young children, they are only able to physically express aggression, but as their language and cognitive skills develop, so do their abilities to demonstrate aggressive behaviours in new ways.
Conclusion - The research concludes that there seems to be a strong genetic component to physical aggression but not social aggression, which is more likely due to environmental effects. Children who were physically aggressive were also more likely to display social aggression, probably because of interactions between genes and environment. As children grow, they tend to become more socially aggressive because of social conventions on physical violence and developing different ways to express themselves.
Evaluate Brengden et al 2005 Contemporary
Sample- 332 Twin pairs from Quebec New-born twin study, born between November 1995 and July 1998
234 participants used in results (All gathered)
MZ- Male- 44, Female- 50, DZ- Male- 41, Female-32, Mixed pairs – 67
Sample is strong in the fact that it is large, meaning that anomalies (Children with too high or too low aggression levels) will be averaged out, more representative and more generalisable, however a limitation of the sample is that it excluded 88 ppts who may have unique or unusual backgrounds, may limit generalisability of study (Limitation).
Method 1- Study didn’t control for extraneous variables i.e. twins influencing one another’s behaviour, which can limit internal validity of results (Limitation).Twin studies are a valid means of studying nature vs nurture - MZ twins share 100% of their genotype, DZ no more than 50% - both share same home life - if MZ twins share behaviour that DZ do not, it’s likely due to genotype (Strength).
Method 2- Study uses pre-existing questionnaires which can be replicated and results can be tested for reliability (Strength), the questionnaires are limited in reliability as they were translated, questions could be mistranslated and original question could be lost, resulting in inaccurate and unreliable answers (limitation).
Conclusion- Physical aggression caused by genetics and social aggression caused by environmental factors
Physical aggression can result in social aggression i.e. Young child may be physically aggressive, as they grow they may develop in language and cognition, leading to them developing more socially desirable way of aggression (Social aggression)
The conclusions have high application to early interventions for social aggression to prevent factors such as bullying occurring, if a child of young age is showing early signs of physical aggression, this insinuates social aggression may occur, so should provide anti-bullying classes alongside interventions for physical aggression (Anger-management). (Strength)
To conclude, study is highly strong in its replicable method of questionnaires which allows for results to be tested for reliability, the results are highly applicable to understanding and intervening in social aggression, however the study lacks control, resulting in lowered external validity of results, study involves limited, unrepresentative sample (88 Ppts excluded) which limits generalisability for results.
Name the Key Words for Correlational Research
- Correlation- Relationship between two co-variables
- Co-variables- Two quantitative variables that may change
- Positive correlation- Positive relationship between two co-variables, as one increases, so does the other
- Negative correlation- Negative relationship between two co-variables, as one increases, the other decreases
- Zero correlation- No pattern
- Scatter graph- Shows correlation/relationship between two sets of data/co-variables by means of using dots
- Correlational co-efficient/ spearman’s rho- Number between 1 (Pos) and -1 (-) to tell strength and direction of relationship between variables. If number Is close to 1, it’s strong positive, if it’s closer to -1, it’s strong negative
- Trend Line/ Line of Best Fit- The ‘line of best fit’ is a line that goes roughly through the middle of all the scatter points on a graph.
The closer the points are to the line of best fit the stronger the correlation is.
What are Issues with Correlational research?
- Cause-and-effect cannot be established- Relationship may be coincidental.
- If extraneous variables influenced results, we wouldn’t be able to tell with correlational research
- Correlations are a starting point for research- They use secondary research collected by other researchers to investigate relationship between two co-variables and then design experiment based on that
Correlational research relies heavily on self-reported data, which can be biased or inaccurate.
What is Spearman’s Rho?
- Spearman’s Rho is used for looking at the relationship between two co-variables (i.e. Pairs of scores)
- Data must be at least at an ordinal level (ordinal, interval or ratio)
- It is based on comparing ranks of the pairs of scores
- If ranks are similar, this would suggest a positive correlation
If they are not, it would suggest a negative correlation
Describe and Evaluate Computerised Axial Tomography
CAT
Passing X-rays into the head, but unlike a standard X-ray where beam is focused on specific area, multiple beams are passed around head at different angles to gather info. Detailed images developed by computer interpretation
- Strength- They’re quick to conduct and can give accurate details of brain structure to advise treatment and plan a surgery.
Limitation- X-rays in CAT can pose a risk to patients as they involve radiation exposure,
Strength- cost-benefit analysis conducted where they’re only used if benefit of diagnosis outweighs radiation risk.
* Limitation- X-ray exposure can damage unborn baby of pregnant women
Describe and Evaluate Positron Emmision Tomography
PET
Form of nuclear medicine procedure, they involve injecting the patient with a small amounts of radioactive material in order to conduct the scan. Patients having PET scan of brain will be injected by Fluorodeoxyglucose (FDG), which is tracer substance absorbed into the bloodstream. A task may be used to stimulate their brain (Raine et al 1997) and encourage activity. As brain is working, gamma rays produced in areas of high activity and these are picked up by scanner. Areas of high activity may have a red colour while areas of low activity may have blue colour.
- May predict what kind of issues patients may face in low brain activity areas.
- Useful In investigating brain areas which aren’t functioning properly.
- Compare functions between normal and abnormal brains so can identify causes of differences in behaviours.
- Produce quantitative data which is reliable.
- Used in research such as Raine et al (1997) where PET scans were used to investigate brain activity of murderers and control group of non-murderers
- Scans more invasive as patient may be injected with radioactive substance, but carries low risk due to very low levels of substance, unclear long-term effects may reduce use of PET.
- Carried out in controlled setting so cannot show how brain responds in real - life situations, therefore low in predictive validity.
- Involve use of unrealistic tasks so results are low in ecological validity.
