Research methods in Psychology
Although you might not think about it immediately, how you conduct psychological research is at least as important [in fact more important] than subject of the research you conduct. Here is a quick introduction to some of the key ideas in psychological research.
Formulating research questions - aims and hypothesesAim – a general statement about the purpose of an investigation
Note that the variables are clearly operationalised [it is clear how we would measure them], a prediction is made and it could be easily tested. |
Creating aims and hypotheses allows Psychology to follow the SCIENTIFIC METHOD. This is one of the key things that differentiates Psychology from common sense explanations of behaviour [see the 'Psychology vs common sense' section below]
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| Extraneous and confounding variablesAn extraneous variable is a variable other than the IV that might affect the DV if it is not controlled. Extraneous variables must be carefully and systematically controlled so they don’t vary across any of the experimental conditions or, indeed, between participants. When designing an experiment, researchers should consider three main areas where extraneous variables may arise:-
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Confounding Variables - variables that do actually have an effect on the DV. A confounding variable could be an extraneous variable that has not been controlled.
If the IV is the only thing that is changed then it must be responsible for any change in the DV.
[N.B. - if we fail to identify & control for an extraneous variable, and we only notice afterwards that it has affected our results, then it
becomes known as a confounding variable.
EXAMPLE: if researchers wished to investigate the effect of background music [condition 1] or silence [condition2] on homework performance using two classes, they’d have to control a number of possible extraneous variables. These might include age, homework difficulty and so on. If these were all successfully controlled, then the results would probably be worthwhile. However, if the
researchers discovered that those in condition 1 were considerably brighter than those in condition 2, and then intelligence would be acting as a confounding variable. The researcher could no longer be sure whether any differences in homework performance were due to the presence of the music or due to intelligence levels. Results would be confounded and worthless.
Populations and sampling
Once we have our aim and hypothesis, we have to decide who we want to do our research on. Research will often only be relevant to certain groups of people [all females, or all teenagers, or people suffering from depression etc]. We call the group of people we want to apply our research to the target population.
Ideally we would do out research of all of the members of the target population, but this is almost never possible due to the constraints of time, cost and logistics. Instead, psychologists take a selection of the target population called a sample. Psychologists try not to use a biased sample -that is a sample that is not representative. Representative here means including members of each type of person in that population, usually in the correct proportion. It is difficult to get a representative sample because there are problems in obtaining participants, even if you can get access to relevant people, you still have to choose who will be involved. | Identify the target populations.Identify the target population in the following |
Sampling methods and their evaluations...
Opportunity sampling Is not really a true method of sampling because it means taking whoever is available. Researchers take whoever they can find to take part. The way participants are selected is not systematic or structured. Psychology students tend to use opportunity sampling as they have limited access to participants
| Random sampling Here every member of the target population has an equal chance of being selected. Everyone in the target population is available for selection each time a participant is picked out. Strengths
Weaknesses
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Stratified sampling
| Systematic Sampling
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Types of experiment in Psychology
Laboratory ExperimentsThese take place in either a lab or in a controlled environment setting, which is unnatural for the participants. They attempt to control all variables except the IV. By changing one variable [the IV] while measuring another [the DV] while we control all others, as far as possible, then the experimental method allows us to draw conclusions with far more certainty than any non-experimental method. If the IV is the only thing that is changed then a cause and effect relationship can be found between the IV ad the DV. | Field ExperimentsField experiments take place in 'the field'... not in a fieldSometimes it is possible to carry out experiments in a more natural setting, i.e. in ‘the field ’. A famous example of this is the series of studies carried out by
Piliavin et al [1969] in which they arranged for a person to collapse on an underground train and waited to see how long it was before the person was helped. | Quasi ExperimentsComparing men and women's performance on this task would be a quasi experiment as we cannot choose who is in each group in the experiment.May take place in the lab or field. Like other experiments they have an IV but in this type of experiment the experimenter does not directly manipulate the IV. Some IVs are not open to manipulation as some conditions are pre-decided by fixed characteristics. E.g. comparing men and women’s driving skills, they cannot be randomly allocated to be male or female. The IV is naturally occurring. Other examples of pre-existing variables might be age, IQ, position in the family and social background. |
Think like a Psychologist - evaluating types of experiment
| Evaluating the different types of experiment is very straightforward, as soon as you understand that THE ADVANTAGES OF ONE DESIGN ARE THE DISADVANTAGES OF THE OTHER. If you understand this then you actually don't have to revise as much information, as you can reuse the same ideas in a number of different places! For example, a lab experiment will try to tightly control variables in an artificial setting. This means that it is less likely that any confounding variables will affect the results [so cause and effect relationships can be discovered between the IV and DV], but is also means that the situation will have very low ecological validity. This means that the situation does not resemble real life, so there is a danger that the behaviour produced by participants will not be realistic as a result. If this is the case, then we cannot generalise the results of the experiment to real life behaviour [in effect the results of our experiment are worthless as they don't tell us anything about the real world]. A field experiment will be the opposite. It will have high ecological validity as it occurs in a natural setting, but the poor control of extraneous variables makes it much more likely that they could affect the DV and confound the results.A quasi experiment has the obvious drawback that the researcher is not properly in control of the variables involved, so again there is the possibility for the results to be confounded. |
Want another example of a place where you can save yourself work by just understanding that the strengths and weaknesses of different ideas will be related...? Look at the evaluations of the experimental designs section below, or of the sampling methods above! The same patterns occur...
Experimental designs
As well as the type of experiment that you conduct, there are a number of ways that experiments can be designed. What we mean by this is the way that the experiment puts people into groups. The three main examples of this are below:
Independent groups [or 'independent measures']Different people in each conditionTwo independent [separate] groups of participants. Disadvantages: | Repeated measuresThe same people do each conditionEach participant takes part in both conditions of the experiment. E.G. each participant learns in silence and with music and does the memory task after each. Advantages: | Matched pairsHere participants have been matched for age [e.g. as age might affect memory, we make sure that our two groups contain similar ages]. In a memory study, we might also match for IQ and so on...Like an independent groups design but you carefully match members of each group. If you have a 23yr old rugby player in one
group you need one in the other group. If you have a female with an IQ of 150 you need one in the other group and so on... Disadvantages: |
Non-experimental methods
Experiments are not the only way that psychologists can investigate behaviour. There are many other non-experimental methods which are widely used in the subject, such as correlation studies, content analyses, observational studies, case studies, questionnaires and interviews. Bandura et al [1961], Piliavin et al [1969] and Rosenhan [1973] are all good examples of observational studies from the CIE course.
Observational studiesOne of the simplest research methods, this simply involves observing and recording the behaviour that occurs. However, in order to make the process more scientific, a number of checks are often put in
place... Observation studies can be participant observations, where the researcher joins the group being studied, or non-participant observations, where the researcher stays apart and observes from a distance. | CorrelationsSometimes psychologists are interested in whether there is a relationship between two factors or variables, e.g. is there a relationship between how extrovert you are and how good at maths you are. In a case like this we might use a correlation. In a correlation
study the experimenter does not make any attempt to manipulate variables [so there is no IV or DV], he simply measures two things [e.g. maths scores and extroversion] and then compares them for a relationship [e.g. does it seem to be that as maths scores increase, so do extroversion scores].
| Case studiesThe case study of Phineas Gage is one of the most famous in PsychologyA case study involves a detailed investigation of a single individual or small group of individuals. Example of the type of research that would lend itself to a case study are investigations into the
effects of a stroke on later personality and behaviour, studying the effects of severe deprivation and the possibilities for recovery and so on. Freud's case study of Little Hans and Thigpen and Cleckley's report of 'The three faces of Eve' are both examples from the CIE specification of a case study. |
Applying your understanding to a real study - The Marshmallow Test
| First watch the video to the left, then open the document below. In the summary of the experiment table of the document, fill in the gaps in the description of the study with the appropriate answers, based on what we’ve done in the last few lessons. TIPS! |
Want more practice...? Firefly is your place
Log into the JIS Firefly page and find the 'Research methods' section in the 'Psychology' pages ['Humanities' section] for lots more resources and practice opportunities.