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Research methods in psychology
Transcript of Research methods in psychology
in psychology Research
methods Experiments Lab experiment All the variables are controlled.
Participants know they are in an experiment. Low EV.
IV manipulated, DV measured. Field experiment Some variables are controlled.
Participants may not know they are in an experiment. Natural environment. Natural/Quasi experiment Occurs in a natural setting. The IV is naturally occurring. High EV. Strengths High levels of control over
variables means 'cause and effect' relationships can be established.
Easy to replicate so results can be checked for reliability. Weaknesses Artificial situation and usually unusual tasks so low ecological validity.
Participants may respond to demand characteristics so results less reliable and valid. Strengths As it is in a natural environment there is greater ecological validity, so more applicable in real life.
There are lower demand characteristics so results are more valid. Weaknesses Harder to control so difficult to replicate, therefore results may not be reliable.
May be unethical if people are not aware of being studied. Strengths There is greater ecological validity as real groups are used, so results are applicable to real life.
Allows researchers to investigate areas that would otherwise not be available to them so useful Weaknesses There is a lack of control over IV which makes it difficult to establish cause and effect between variables.
Difficult to replicate so results are less reliable. Correlations Positive correlation When one variable increases the other increases. Negative correlation When one variable increases the other decreases. Zero correlation No relationship
between the variables (The researcher does not manipulate the variables but only measures the relationship between them) Strengths They can be used where ethical manipulation would be unethical or impossible.
They can suggest further avenues of study to find causation. Weaknesses They examine the strength of a relationship only, not a cause and effect between variables.
The relationship may be affected by extraneous variables. Self Reports Interviews Involves face to face questioning
between researcher and participant, usually a discussion. Questionnaires A written or printed form used in gathering information on participants, consisting of a set of questions to be submitted to one or more persons. Structured self-reports: A researcher uses a list of pre-set questions and participants choose their responses from a list of fixed alternative responses, which can then be collated and analysed. Semi structured self reports A researcher uses a list of pre-set questions but the participants' responses are not fixed as they can express their own views. Open-ended self reports A researcher will not use pre-set questions, instead asking participants to comment on a particular topic in their own words, allowing them to express their views freely. Open ended questions A question with an open, qualitative option for response. Closed questions Requires a participant to choose from a limited number of options e.g. yes/no or the use of a rating scale e.g. likert scale. Strengths Allows research to find out things that cannot be easily discovered by other methods (attitudes, beliefs, opinion).
Structured questionnaires (closed questions) create quantitative data so are objective. Open ended questionnaires create qualitative data so are more detailed. Weaknesses Can't establish cause and effect as numerous factors may affect participants' responses to questions.
Participants may not respond truthfully, if they wish to present themselves in a socially acceptable manner. Strengths Structured interviews allow standardised procedures to be used (same questions in the same order), so results are more reliable.
Unstructured interviews provide information that is more spontaneous and realistic creating qualitative data that offers detailed insight into a person's beliefs and attitudes. Weaknesses Unstructured interviews don't allow generalisation of findings as different participants will offer different responses which can't be compared.
Structured interviews don't allow participants to express their opinions as freely so are less detailed. Observations Types of observations Natural observation An observation that contains no manipulations and participants are observed in their natural environment. Controlled observation Involves the researcher setting up situations which participants are then observed in (e.g. Milgram). Participant observation Some participants obtain data via their own observations in real life settings (e.g. Rosenhan). Structure of observations Unstructured observation Will largely be qualitative as a report of all behaviours may be taken down by the researcher e.g. Reicher and Haslam used some unstructured observation. Structured observation Uses specific categories (usually in a tally chart) to break the participants behaviour being investigated down into clear unambiguous categories (e.g. Bandura's categories). Time sampling Recordings are taken at a chosen time interval e.g. every 1 minute. Event sampling Recordings are taken every time a given behaviour is exhibited e.g. every time someone uses their phone - alone or in a group. Strengths Likely to provide inside information about people's behaviour.
Occurs in the participants natural environment while they are taking part in everyday activities so is higher in ecological validity. Weaknesses Objectivity may be reduced due to observer being involved with the participants.
Can't replicate as the situation is a one off and so can't check reliability. Strengths Help us identify actual behaviours rather than what people say they do in actual situations so should be a valid representation of behaviour.
Allows us to capture spontaneous and unexpected behaviour that occurs in the real world and so is higher in ecological validity. Weaknesses Ethics could be an issue if participants don't know they are being observed then this leads to deception and invasion of privacy , but if they do this may alter their behaviour leading to demand characteristics.
Observer bias may lead to unreliable data as observers may "see" what they expect to see. Strengths Enables systematic observation to be made, so controls can be implemented so that consistency of the data can be checked for reliability.
Allows quantitative data to be collected so results are more objective. Weaknesses Categories may not cover all possibilities so some behaviour may be left unrecorded or placed in different categories which will lower validity.
Collecting quantitative data only tells us that behaviour occured and not why, so may lack detail. Case studies Strengths Allows quantitative and qualitative data to be collected as a range of methods can be used to study a single person or small group.
More likely to reach a valid conclusion as it takes a holistic approach to studying a single person or small group. Weaknesses Tends to lack generalisability as only investigates causes of behaviour in a small sample of people.
Can be affected by subjectivity due to researcher bias due to forming a relationship with the researcher. Hypotheses Research/alternate hypothesis States that there will be a significant difference between the groups. There will be a significant correlation between the two variables (in correlational research). Null hypothesis States there will no significant difference or no significant correlation between the two variables. Difference would be due to chance. One tailed hypothesis States a direction the results will take e.g. which group will be significantly greater/lower than the other. Two tailed hypothesis Leaves the results open. Only predicts a difference between groups. Experimental
designs Independent measures
design Only take part in one condition.
+ Avoid practice/order effects.
- Individual differences reduce validity
and/or reliabilty. Repeated measures
design Participants take part in all conditions.
+ Avoid individual differences.
- Order effects do affect research. Matched pairs design One condition but participants matched on key personality variables.
+ No individual differences of order effects.
- Time consuming. (counterbalancing - first group -AB
second group BA) Extraneous Variables Situational variables Aspects of the research situation that could affect the outcomes, e.g. weather. Participant variables Aspects of the participants' characteristics or experiences (other than the IV) that could affect the outcomes. Experimenter variables The effects of the researcher's presence or expectations that could affect the outcomes (intentionally or unintentionally). Sampling Opportunity It involves the researcher selecting anyone who is available and willing to take part in research. Advantage Quick and easy to obtain so a large number of participants can be recruited without too much effort. Disadvantage Participants are likely to have a similar background so the results are likely to be biased and not generalisable to wider population. Self selected A self selected/volunteer sample involves participants selecting themselves, often through replying to an advertisement. Advantage Useful when the research requires specific type of participants. Anyone can apply to participate so could be considered random and therefore generalisable. Disadvantage Can be expensive and requires a lot of effort. The findings might be biased as only certain types of people are likely to apply, therefore not generalisable. Random Every person in a given target population stands an equal chance of being selected for inclusion. Advantages Most representative as everyone has an equal chance of participating, so the findings are generalisable. Disadvantage Unless the target population is small it is very difficult to obtain a list of all the people who would be required. Data analysis Nominal data The number is just a label or a name of a category. Nominal data counts the number of times something has occurred in a given category. This data only works out the proportion of something, it's not possible to work out central tendencies and is best displayed as a pie chart or tally chart. Ordinal data It involves numbers that can be put in order or ranked but don't have any other mathematical properties. Any data that creates a score can ordinal, especially data collected from self-reports, questionnaires, preference rating scales or observations. It can be displayed in a bar chart. It can't tell us the difference between scores that might vary. Interval and ratio data It allows us to understand the difference between scores rather than just the relationship between them. In internal data the points on a scale must be equally spaced - the data is measured in equal units e.g. temperature. It involves both positive and negative values, unlike ratio data that has an absolute zero - most precise. It is referred to as "at least interval data". Measures of central tendency - mean, median, mode.
Measures of dispersion - range. Levels of significance In psychology the minimum acceptable level of probability that the results was caused by chance is 5%, we have to be at least 95% confident that our findings were caused by the experimental manipulation of variables.
Significance levels can vary between 0.00 and 1.00 but the magic number is p≤0.05 (smaller to or equal 0.05). If results are found to be significant at this level, the null-hypothesis can be rejected and the alternate hypothesis can be accepted. Type 1 error - Accepting your experimental hypothesis but that was a mistake.
Type 2 error - Accepting the null hypothesis but that was a mistake. Types of inferential tests Chi-Square test Nominal data
Value of chi Sign test Nominal data
Difference between two conditions
Repeated measures design
Value of paired X and Y Wilcoxon Signed Rank Test Ordinal data (or internal if necessary)
Difference between two conditions
Repeated measures design
Value of W Mann-Whitney U Test Ordinal data (or interval if necessary)
Difference between two conditions
Independent measures design
Value of U Spearman's rank Correlation Coefficient Ordinal data (or interval if necessary)
Relationship between two variables
Value of rho Approaches and perspectives in psychology Physiological approach Assumptions All behaviour is due to nature - all behaviour that is psychological is first physiological. Since the mind appears to reside in the brain, all thoughts, feelings and behaviours ultimately have a physiological cause and therefore behaviour has a 'nature' basis.
Psychology is a science. Advanced technology can be used to investigate the effects of biological activity on behaviour in a very controlled and scientific way. AS study that supports the physiological approach - Dement & Kleitman This study relates to the assumptions of the approach because D+K are investigating a biological process (stages of sleep + REM causing dreaming) that we assume is universal and entirely due to nature. Sperry Maguire A2 study that supports the pysiological approach - Raine This study relates to the assumptions because he examines the role of the brain (functions of the brain) in causing criminal behaviour. Brain functioning is a biological process. Brunner Strengths of the pysiological approach This approach is reductionist as it focuses on studying the biological causes of human behaviour in order to establish cause and effect between different aspects of our physiology and behaviours.
Raine was able to show how abnormal functioning of different areas of the brain could determine the likelihood of someone committing a violent act such as murder by using a highly controlled reductionist peice of research.
This is useful because isolating biological factors that affect our behaviour can lead to many practical applications as drug treatments can be designed to help people with mental or social disorders. Strengths continued The physiological approach relies mostly on the use of scientific methods using highly controlled experiments since physiological processes are governed by the physical laws of science. Maguire uses MRI scans then pixel counting and voxel based morphometry to calculate the size of a participants hippocampi. Research can be checked for reliability both cross culturally in different parts of the world and at different times to check the reliability of the research. Weaknesses of the physiological approach Behaviour is often studied in artificial environments due to the use of technical equipment so the findings lack ecological validity as they are studied outside the social content in which the behaviour would usually occur. D+K could only tell what stage of sleep people were in (REM/NREM) and couldn't show in any concrete way whether the person really was dreaming or showing demand characteristics. Research is less useful as the results may not reflect how behaviour occurs in everyday life and so aren't a true representation of what has caused behaviour to occur thus reducing the validity of the research. Weaknesses continued This approach can also lead to ethical concerns as it argues that many behaviours have genetic origins which leaves open the possibility for society to eradicate behaviours that are undesirable (e.g. crime). Brunners research could lead to society testing individuals for genetic faults that cause abnormal levels of serotonin which could result in these people being removed before committing a crime. This could lead to issues with social control where research could be used for political motives causing psychological harm to individuals in society. Cognitive approach Assumptions Cognitive psychology is pure science, based mainly on lab experiments. Behaviour can largely be explained in terms of how the mind operates, i.e. the information processing approach (examining input, process and output). The mind works in a similar way to a computer: structure = hardware, mental processing = the software. Studies that support the cognitive approach - AS - Baron - Cohen The research examines the flow of information through different brains (tourettes/autistic/normal) in terms of input (eyes) and output (judgment on emotion) to infer what cognition is taking place within these participants. Studies that support the cognitive approach - A2 - Gudjohnsson & Bownes This research examines the flow of information through different brains (sex offenders/violent offenders) in terms of attribution of blame to infer what cognition is taking place within these participants. Strengths of the cognitive approach This approach is reductionist as it focuses narrowly on studying mental processes (memory, perception, reasoning, problem solving) in order to establish the extent to which these influence behaviour (cause and effect). Baron Cohen's study was reductionist by using a highly controlled matched pairs experiment using the eye task to demonstrate that the central deficit of autism is a failure to fully develop this cognitive process of theory of mind. This is useful because, isolating factors that affect our behaviour can lead to many practical applications as cognitive treatments can be designed to help people with mental or social disorders. Strengths continued Cognitive research also relies on the use of highly controlled scientific experiments to find out the extent to which our mental processes affect our behaviour and experiences. Loftus and Palmer were able to control the age of the participants, the use of video and the location of the experiment. All participants were asked the same questions (apart from changes in the critical words) and the position of the key question in the second was randomised. The research is likely to be reliable as it is easier to replicate due to using standardised procedures to consistently show that factors such as mental processing could be the cause of behaviour. Weaknesses of the cognitive approach Behaviours are studied in artificial and highly controlled environments so the findings lack ecological validity as they are studied outside the social context in which it would usually occur. Loftus used slides to present someone either pulling a gun or a cheque out in a restaurant. Viewing such incidents on slides wil not reflect the real life feeling such as arousal in a real life scenario where a gun is present. This makes research less useful as the results found may not reflect how behaviour occurs in everyday life and so are not a true representation of what has caused behaviour to occur thus reducing the validity of the research. Weaknesses continued Mental processes are very difficult to study
in isolation as they can't be directly seen but only inferred, which means that other factors could be influencing people's behaviour creating low validity as you can only measure what the person wants you to know rather than what they are actually thinking. Gudjohnsson and Bownes could only rely on what the convicted criminals reported to them, and the criminals may have had ulterior motives such as guilt or wanting to present themselves in a socially desirable way to researchers. This means that researchers can't be always confident that they are studying the effects of mental processes which make the findings less useful as the person could be displaying demand characteristics as they don't want the researcher to know what they are thinking. Developmental approach Assumptions Psychological changes occur through a person's lifespan, not only because of their physical maturation but also because of their experiences. Rapid changes occur during childhood and these should be studied in detail. It supports the nurture debate because it argues that we are born as "blank slates" and childhood experiences will affect later adult life. This approach studies behaviour from the moment of birth, to early childhood experience to later adult life. Studies that support the developmental approach - AS - Bandura This study supports the developmental approach because it demonstrates how children learn aggressive behaviour from same sex models and how girls and boys are socialised differently to display different types of aggression. Studies that support the developmental approach - A2 - Farrington This study supports the developmental approach because it demonstrates how children can learn criminal behaviour from their childhood experiences such as having a convicted parent or delinquent sibling but most of all how being brought up in a large family could result in poor parental discipline. Strengths of the developmental approach This approach is holistic as it considers a variety of social, cognitive and physiological factors as well as people's individual differences as influencing people's behaviour and experience as they develop. Farrington's cambridge study on disrupted families utilised a variety of resources in order to investigate why people TTC such as school truancy records , criminal records, interviews about their home life and personalities etc. This is useful because it allows a greater understanding of human behaviour by recognising that a combination of factors affect the way in which we develop over time. Strengths continued Developmental research uses case
studies which use a variety of methods when studying the ways in which people change over time which means that it tends to collect qualitative and quantitative data. Farrington's study was a longitudinal study, and was carried out over 40 years. During this time he collected qualitative data (e.g. reasons why they committed the crimes) and quantitative data. This is useful as it allows us to understand not only how people behave but also why they behave in certain ways, leading to practical applications such as policies that would help improve people's lives (e.g. education, care facilities for elderly etc). Weaknesses of the developmental approach The samples used in research are restricted to people of the same background or age group (often children) and are not representative of the target population. In Freud's study of a little boys phobia of horses, only Little Hans was studied in depth between the ages of 3 and 5 and his phobia was only unique to himself. The findings obtained in developmental psychology are often low in generalisability as they can't be applied to a wider group of people, making the findings less useful. Weaknesses continued Another problem with the developmental approach is ethics as the research often (although not always) involves studying children, some of whom don't give informed consent, or understand they have the right to withdraw. In Bandura's study on imitation of aggression, the children were exposed to an aggressive adult role model who was punching and kicking the bobo doll in a stylised manner, the children were to young to give consent or understand the concept of withdrawal. This is a problem because even if all the ethical guidelines are followed, critics would argue that children could never give informed consent as they may not understand the implications of taking part in research and so may cause psychological harm. Individual differences approach Assumptions All humans are different and it is important to consider the differences amongst people and how these affect behaviour as well as just considering the 'average person'. Each of us has a unique set of life experiences which has contributed to making us what we are and these can account for some of the differences between individuals. Studies that support the individual differences approach - AS - Thigpen & Cleckley Relates to individual differences approach because T+C studied someone who was not the average person (Eve) who was suffering from an unusual disorder (MPD). Studies that support the individual differences approach - A2 - Gudjohnsson Relates to the individual differences approach because FC was not the average person in terms of scoring 10 on the Gudjohnsson suggestibility scale and was also unusual to the norm because not many people would confess to a murder they had not committed. Strengths of the individual differences approach Allows psychologists to investigate individuals who don't fall into the norms of society allowing psychological disorders to be understood.Griffiths studied an abnormal group of gamblers to gain an insight into how cognitive bias can encourage gambling. This is useful because it helps us understand the differences between people, leads to practical applications in terms of treatments for psychological disorders. Strengths continued The approach often uses in-depth case studies allowing for plenty of qualitative data to vertify any quantitative measures taken. T+C, over a number of months, used experts to carry out quantitative psychometric tests on Eve and EEGs and qualitative data from interviews, family accounts and personality tests. Due to this level of depth of understanding, the research can be seen as valid in understanding some of the most vulnerable individuals in society. Weaknesses of the individual differences approach There is an over reliance on research which can have limited, often unrepresentative samples as case studies are frequently used. Gudjonsson's case of FC reports an individual who was highly suggestible (10 on G's scale) which means the research doesn't represent how the majority of people would react under questioning about a murder they didn't commit. This is a problem because research may be of limited use in understanding the significant majority of a population and will therefore be of limited use compared to other approaches. Weaknesses continued There are problems with ethics since research focusing on individual differences can create labels, such as "abnormality" which may cause people to become socially isolated. Rosenhan's study was particularly critical about both the reliability of labelling and the negative effects labelling has on a person. Such labels, particularly negative ones can lead to a self fulfilling prophecy in which expectations about a person or group can become true simply because of those expectations. This could cause serious psychological harm to certain groups of people as it could feed negative stereotypes, lead to social exclusion and discrimination against certain groups of people. Social approach Assumptions The social approach assumes that other people and the surrounding environment are major influences on an individuals behaviour, thought processes and emotions. The social approach therefore takes the view that our behaviour is nurture as it suggests all behaviour comes from our social environment. Studies that support the social approach - AS - Milgram Milgram can be considered a social approach study because the environment in which the participants were in was one of the factors as to whether the participants were obedient or not. Studies that support the social approach - A2 - Farrington Farrington can be considered a social approach study because it was due to the area that they lived in and family circumstances that the boys committed crime. Strengths of the social approach This approach is reductionist as it focuses narrowly on the social processes that occur between people (e.g. obedience) in order to establish the extent to which these influence behaviour (cause and effect). Piliavin can be useful in understanding why bystander apathy can occur and could recommend the introduction of a law that meant if you didn't help you would be liable for prosecution. This is useful because isolating factors that affect our behaviour can lead to many practical applications as different situations can be encouraged (e.g. helping) or avoided (e.g. discrimination) in order to avoid or encourage behaviours from occurring in the future. Strengths continued An advantage is that this approach is deterministic in understanding the development of extreme behaviours in society.
Reicher & Haslam's research argues that the emergence of a tyrannical regime is determined by factors such as the failure of democratic groups due to members of these groups not sharing values and ideas. This is useful because if we can determine the causes of behaviour such as prejudice, blind obedience and tyranny, then we can potentially reduce the chances of these recurring in society. Weaknesses of the social approach One problem is that research can place participants in extreme social situations, resulting in unethical research due to breaking guidelines like consent and protection from harm. In Milgram's research participants didn't give consent to take part in research into obedience, they were decieved. Also, they were put in stressful situations. This is a problem as it could lead to psychological harm of participants, and could deter participants from volunteering for future research, jeopardising the recruitment of future samples in psychology. Weaknesses continued Another problem is that research used to support the approach often uses restricted samples as most of the research has been conducted in the West (USA,UK). Farrington's research was conducted on 411 boys in East London who will not represent why young males from other cities with different socio-economic conditions would turn to crime. This is a problem because findings can't be generalised to similar populations in different cultures, making the findings less useful as they aren't representative of how social behaviour may occur in other places. Psychodynamic perspective Assumptions All behaviour can be explained in terms of inner conflicts of the mind. For example in Freud's study Hans' phobia of horses was caused by a displaced fear of his father.
The psychodynamic perspective emphasizes the role of the unconscious mind, the structure of personality and the influence that childhood experiences have on later life. Studies that support the psychodynamic perspective - AS - Freud Freud's study was psychodynamic because Hans was showing an unconscious desire for his mother which was a psychodynamic concept of the oedipus complex. Studies that support the psychodynamic approach - A2 - Gudjohnsson This is a psychodynamic study because FC used the unconscious defense mechanism of reaction formation which reduces anxiety by taking up the opposite feeling e.g. confessing even though not guilty. + Thigpen & Cleckley Strengths of the psychodynamic perspective This perspective relies largely on the use of case studies and qualitative data to investigate unique cases as means of finding out about the causes of people's behaviour and experiences. Freud used a case study to investigate Hans as an individual gaining extensive qualitative data e.g. written accounts of Hans' dreams which were interpreted to find the cause of his phobias. This is useful because it allows us to understand not only how people behave in certain situations but also the reasons why they behave in particular ways by investigating small groups in-depth. Strengths continued The psychodynamic perspective has highlighted the importance of early childhood interactions on the development of adult personality so increasing our understanding of human development. In T+C's study of Eve, it was later revealed that she had witnessed the death of a man when she was young which may have triggered her MPD as a defense mechanism. This is useful because it helps inform people working with children about the ways in which childhood interactions could be assisted to ensure healthy development of an adult (e.g. parenting classes, organisation of child care facilities) so has many practical applications. Weaknesses of the psychodynamic perspective A big problem is that it relies on the use of unique case studies as means of studying people's behaviour and so research may lack controls that would help determine the factors that affect that behaviour. Freud had limited contact with Hans, largely relying on subjective accounts from Max Graf (Hans' father) which opened the possibility of biased reports from Max and bias interpretation from Freud. This means that the findings may not be valid and not reliable as they are open to subjective interpretation by the researcher who may develop a close bond with the subject of the case study, therefore may be less useful. Weaknesses continued Another problem is the use of restricted samples as the research is often carried out using a very small number of participants. Gudjohnsson's case of FC reports an individual who was highly suggestible (10 on G's scale) which means the research does not represent how the majority of people would react under questioning about a murder they did not commit. This means the findings are low in generalisability as they can't be applied to a wider range of people since each person's experiences may be unique, so this makes it less useful. Behaviourist perspective Assumptions The behaviourist perspective believes
that observable behaviour can be studied,
as cognition and moods are subjective. Our responses to environmental stimuli shapes our behaviours e.g. Bandura studied aggression in children using lab experiments. We see people acting aggressively and copy this ourselves. Also assumes that behaviour is a product of our environment (nurture). Punishments and rewards determine the likelihood of it being reproduced e.g. Leyens. Studies that support the behaviourist perspective - AS - Bandura This relates to the behaviourist perspective because this research demonstrates that children learn behaviour through observation and imitation of those around us. It also supports the assumption that environmental influences affect our behaviour - thereby suggesting that aggressive behaviour is learnt via nurture rather than a genetic link. Studies that support the behaviourist perspective - A2 - Leyens Leyens research relates to the approach by showing that delinquent boys are more likely to be aggressive depending on their nurturing environment (level of aggression in the films viewed). It also supports the idea that our behaviour is moulded by our responses to environmental stimuli. Strengths of the behaviourist perspective This approach is deterministic as it suggests that any behaviour is learned and results directly from our interaction with the environment so predicting a cause and effect. Leyens demonstrates the clear effect that violent media like films can have on delinquent youths. This is useful because is behaviours are learned then they could also be unlearned, which can lead to many practical applications as the perspective can offer a range of behavioural therapies designed to help people with mental or social disorders. Strengths continued Research used relies on the use of highly controlled scientific experiments to find out the extent to which our learning from the environment affects our behaviours and experiences. Controls in Bandura's experiment investigating the imitation of aggression included the fact that children were matched on existing levels of aggression and the behaviour of the models was rehearsed to ensure the same conditions for all participants. This means the research is likely to be reliable as it is easier to replicate due to using standardised procedures to consistently show that factors such as the external world could be the cause of behaviour. Weaknesses of the behaviourist perspective The behaviourist perspective is reductionist as it assumes that all our behaviour is learned through our interaction with the environment, ignoring the influence of nature. Leyens research suggests that the media has a significant effect on easily influenced boys aggression, however this ignores the influence of genes and serotonin (Brunner). This means the perspective ignores dispositional factors by focusing on the situation which reduces the overall validity of the perspective as understanding of behaviour is limited. Weaknesses continued Another problem is that there can be ethical issues with some of the research as studying people's socially undesirable behaviours means that participants could be exposed to negative influences which could cause psychological harm. Leyen's research may have caused more problems for the delinquent boys as the films increased the likelihood of aggression amongst each other in the cottages, It was unethical of researchers to place the boys in a position where harm could be caused. This is a problem as it could lead to damaging the reputation of psychology and can deter participants from volunteering for future research, jeopardising the recruitment of future samples in psychology. Reductionism Whereever you can identify there is a limited explanation Determinism Determinism in psychology is the belief that behaviour is caused by factors outside of our control.