Psychology, psychologists and research methods


Experimental method in psychology

  • Researcher always intervenes directly in a situation by manipulating at least one variable
  • Variable is anything that can be measured and that can change such as age, weight, response times
  • True experiment has 3 key features: Independent variable (IV)
                                                                      Dependent variable (DV)
                                                                      Controlled variables
  • researcher formulates hypothesis that IV will affect DV
  • in simple form of an experiment, researcher manipulates the IV to produce a change in the DV
  • variables must be held constant to ensure the change produced is not due to confounding variables 
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Experimental method

Principle of good experimental design is the random allocation of the groups in a study

Advantages of the experimental method:

  • By holding variables constant between groups, experimenter able to establish a cause-and-effect relationship between the IV and the DV
  • Use of experiments allows researchers to force the pace of research because they don't have to wait for natural events to reproduce the appropriate scenario needed to investigate a particular issue
  • experiment generates quantitative data which can be analysed using inferential statistical tests
  • once the data from research has been obtained and analysed, it can be generalised to the rest of the population


  • many investigations have participants who reflect an overrepresentation of males and of spcific cultures
  • participants usually know they're taking part in an experiment
  • not always possible to carry out an experiment as it may be inappropriate or unethical to do so  
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Lab experiments

Laboratory experiments


  • provide highest level of control over variables
  •  used widely in psychology
  • important to think carefully about the design of the study when reading an account of a lab experiment


  • replicability of procedures: lab experiment can easily be repeated by other researchers to see if similar results are obtained. When results are repeated, confidence is increased in them.
  • Sophisticated measuring and recording equipment is used
  • there is a high level of control over variables


  • loss of validity: experimental situation becomes artificial and different from real life situations
  • demand characteristics: occur when participants try to make sense of situation they find themselves in and adjust their behaviour accordingly 
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Field experiments


  • investigations carried out in natural environment of those being studied
  • experiments attempt to improve realism of research


  • Improved ecological validity: artificiality of the laboratory experiment is avoided, helps eliminate the main critism that findings can't be generalised to real life situations
  • reduction of demand characteristics: participants may be less conscious they're taking part in a research study hence reduction of demand characteristics


  • establishing controls: difficult to establish a high level of control in a field experiment 
  • generalizing to other situations: although realism is high, results can't be generalised to situations that differ from the one in which the expt took place
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Natural experiments


  • researcher makes use of naturally occurring differences in the independent variable
  • means researcher doesn't directly control the IV
  • approach is best described as a quasi-experiment
  • some purists regard it as a non-experimental study

Advantages of natural experiments:

  • reduction of demand characteristics: participants are less conscious they are taking part in an experiment
  • lack of direct intervention: experimenter doesn't intervene directly in the research situation

Disadvantags of natural experiments:

  • loss of control: overall degree of control exercised by the researcher is less than in a lab or field experiment
  • likelihood of desired behaviour being displayed: naturally occurring situation that researcher wishes to study may only occur rarely
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Correlational analysis

Term "correlation" refers to statistical technique that measures the relationship between 2 variables, i.e the extent of which high values on one variable are associatd with high values on another

Many correlation techniques calculate a "correlation co-efficient" a statistic that has a value on a scale between +1 and -1.

Advantages of correlational analysis:

  • measuring the strength of relationships: provide precise quantitative measure of the strength of relationship between variables
  • value to exploratory research: correlational techniques allow for measurement of many variables and relationships between them

Disadvantages of correlational analysis:

  • issue of causality: not possible to establish cause and effect through research investigations using correlational analysis
  • measurement of non linear relationships: cannot be measured by commonly used correlational techniques
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Observational techniques


  • Behaviour is observed and recorded and there is usually no deliberate manipulation of variables
  • provides an alternative to tightly controlled research methods such as lab experiments
  • no attempt is made to influence behaviour being investigated in any way
  • method can be used in situations where other form of intervention would be inappropriate or unethical
  • observational research can differ in several important ways, depends on:
  • setting in which setting is carried out
  • role of researcher
  • the amount of structure imposed
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Pros and Cons of observational techniques


  • value as a preliminary research tool: careful observation can lead to the identification of appropriate hypotheses for further investigation
  • Validity: naturalistic observation can provide a useful means of checking whether experimental findings apply outside lab conditions


  • control: level of control over confounding variables is poor
  • replication: can be difficult due to problems that arise when trying to control variables such as differences between naturalistic settings
  • observer effects: possible observer may change the behaviour of those being observed, especially when a small group is being studied
  • ecological validity and realism: likely to be lower in observational research
  • costs:  can be high
  • coding systems: may limit on constrain how the data gathered are categorized
  • generalizing findings: uniqueness of observational situation may make this difficult
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Self report techniques: Questionnaires

  • Can be used in a wide range of research situations
  • Allows researcher to ask participants about attitudes, behaviours or intentions
  • Can be conducted by post, telephone or via the internet
  • qualititative and quantitative data may be produced 
  • closed questions: researcher determines the range of possible answers, often by ticking boxes or circling answers
  • open ended questions: researcher doesn't restrict range of available answers
  • leading questions: choice of wording used suggests that the respondent should reply in a particular way

How to make a good questionnaire:

  • short questions
  • minimum number of questions
  • word questions carefully
  • avoid emotionally sensitive questions
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Pros and Cons of questionnaires


  • simplicity: questionnaires can be used with minimum training once developed and piloted
  • speed and cost: large amounts of into can be gathered quickly and cheaply within short time frame
  • less interpersonal influence: researchers don't sit with respondents when they complete a questionnaire


  • problem of question wording: ambiguity
  • leading questions
  • different interpreations of language
  • poorly designed questionnaires = poor data
  • response rates are low
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Self report techniques: Interviews


  • common way of carrying out research
  • 3 types of interview: structured, unstructured, semi-structured
  • Structured: aim to produce quantitative data and include pre-determined questions
  • pros of structured:
    - less likely to deviate from topic
    - simpler data analysis
    -less training required
  • Limitations:
    - cannot follow up any lines of enquiry that emerge
    - validity may be threatened due to formality of research situation
  • Unstructured interview: far less rigid and very little will be decidd in advance
  • Usually start of 1 or 2 set questions before broadening the focus
  • Semi structured: most successful approach
  • some questions pre-pared with additional questions giving inteviewee option of expanding 
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Pros and Cons of interviews


  • Flexibility: interview can enable researcher to explore complex issues that would be harder to do using other techniques
  • tackling senitive topics: allows researchers to identify private and personal aspects of behaviour


  • Interpreting data: can occur easily, had to transform qualititative data into quantitative data
  • time and effort required
  • limitations in interviewee's responses: may be unable to articulate thoughts clearly
  • effects of interpersonal variables e.g gender, ethnicity, personality, class or age
  • demand characteristics
  • need for training
  • costs a lot
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Case Studies


  • usually involve in-depth study over time of a "case"
  • usually a single individual or a small group
  • research undertaken within a real-life context
  • may involve a representative case
  • exceptional or unique circumstance may be studied e.g twins separated at birth
  • data mainly gathered through interviews and observation
  • data is usually qualititative


  • rich and interesting data: case studies produce data that has a high degree of realism and can provide valuable new insights into what is being studied
  • challenges existing theory: if findings contradict a well established theory, we have to consider modifying the theory in some way to accommodate for the new evidence


  • low reliability
  • findings may be subjuective: case studies usually based on lengthy in-depth interviews, relationship may be formed
  • distortions: if an individual is required to recall historical events, data can become distorted due to memory errors
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