What is an experimental method in psychology?
- The most scientific method psychologists use.
- Aim to find cause and effect relationship
What is the independent variable and how do you operationalise it?
- Variable that is manipulated to see its effect on the DV
- Must fully state the 2 conditions tested in the experiment.
What is the dependent variable and how do you operationalise it?
- The variable which is measured in the experiment
- For eg if you were measuring intelligence, you would have to do an IQ test to establish a score= operationalising DV
Give examples of participant extraneous variables, and how we would control them to stop them confounding results.
- Age
- Gender
- Height
- Weight
- Mental health
-these can be controlled by only comparing the results of participants from the same group (matched participants). Screening for metal problems, random allocating, double blind experiment
Give examples of situational extraneous variables, and how we would control them to stop them confounding results.
- location
- time of day
- weather
- noise
- temperature
-control the environment the experiment takes place in eg in a lab. Standardisation, pilot study
Give examples of experimenter bias extraneous variables, and how we would control them to stop them confounding results.
- Verbal prompts
- Body language
-Double blind trials, someone to supervise the experiment who is unaware of the aim and experimenter
What is meant by ‘the aim’ of an experiment?
What the research is being carried out for
What is meant by ‘the hypothesis’ of an experiment? Give the 4 different types and their definitions.
A prediction of what the experimenter expects the results of the study to be.
- experimental hypothesis= predicts that there will be an effect between the 2 variables. Results are said to be significant if so
- null hypothesis= predicts that there will be no difference between the 2 variables. Results are said to be not significant if so
- one tailed experimental hypothesis= predicts there’ll be a difference, but states the direction the difference will be. Eg one group will do better then the other
- two tailed experimental hypothesis= predicts there’ll be a difference, but does not state the direction of the difference
For the independent measures experimental design, give a description, strengths for the use of the method, and weaknesses against the use of the method
- when a group of participants are selected to take part in the experiment but are allocated to ONE experimental condition only. The results of the different conditions would then be compared
- Strengths: limited extraneous variables, less order effects, less chance of demand characteristics
- Weaknesses: results are harder to compare due to participant variables (lower internal validity) , require more participants to carry out experiment
For the repeated measures experimental design, give a description, strengths for the use of the method, and weaknesses against the use of the method
- when a group of participants take part in BOTH conditions of the experiment
- Strengths: limited participant variables effecting experiment as it’s the same people, fewer participants are needed to carry out the experiment
- Weaknesses: risk of order effects, risk of demand characteristics, 2 tests have to be carried out at different times=extraneous variables
For the matched pairs experimental design, give a description, strengths for the use of the method, and weaknesses against the use of the method
- Participants are tested and matched with another participant who has a similar skill ability to them. The 2 matched participants are then split into the experimental group OR control group, so that the results can be compared more accurately to demonstrate the effect of the IV.
- Strengths: high generalisability, lower chance of demand characteristics, less chance of order effects
- Weaknesses: hard, tiring and time consuming to accurately match participants, more participants needed to conduct experiment, expensive as equipment may need to be used eg for scanning
For the random sampling technique, give a description, strengths for the use of the method, and weaknesses against the use of the method
- involves identifying everyone in your target population and then choosing how many people you need from the group, giving a completely equal and random chance of being chosen
- Strengths: Best technique for providing an unbiased representation of the target population
- Weaknesses: Very time consuming, almost impossible to actually carry out, asking people to volunteer isn’t random
For the stratified sampling technique, give a description, strengths for the use of the method, and weaknesses against the use of the method
- Classifying the population into categories and then choosing a sample which consists of participants from each category in the same proportions to which they are in the wider population
- Strengths: Very representative of the population
- Weaknesses: Very time consuming
For the volunteer sampling technique, give a description, strengths for the use of the method, and weaknesses against the use of the method
- Participants become apart of the study because they have volunteered when asked or in response to an advert
- Strengths: Quick to carry out, relatively easy to do
- Weaknesses: Type of participants who volunteer may not be very representative of the wider population
For the opportunity sampling technique, give a description, strengths for the use of the method, and weaknesses against the use of the method
- Taking a sample of people from those that are available at the time the study is carried out and fir the correct criteria
- Strengths: Quick and cheap to carry out
- Weaknesses: Can provide a biased sample if the researcher chooses people who they know or are in their cultural group, and participants may decline taking part= self-selected sampling
Out of all 4 sampling techniques, which ones are the best and most commonly used by researchers?
Random and stratified sampling because the results can both be generalised well as there is no chance of bias and sample is very representative.
What sort of environment does a LAB experiment take place in?
-Very controlled and artificial, specialised equipment can be used here.
In a LAB experiment, what control does the experimenter have over the different variables?
- The IV can be manipulated easily
- the DV can be measured in a more in-depth way
- high control over extraneous variables due to the controlled environment
- less chance therefore of confounding variables.
In a LAB experiment, what is the participant selection like/ consist of?
- controlled selection/ grouping
- ppts may be screened
- ppts may volunteer, making them more motivated
Evaluate the use of LAB experiments for conducting psychological research.
STRENGTHS:
P: High internal validity
E: The strict levels of control over extraneous variables due to the controlled environment allows us to establish a trustworthy cause and effect relationship between the IV and DV
E: This is a strength because it means that we can be confident that a change in our DV is due to a change in the IV and nothing else, allowing for progressions in psychology to take place
P: High reliability
E: Lab experiments use standardised procedures and all the ppts receive the exact same instructions in the same conditions
E: This is a strength because it means the study can easily be replicated and results can be compared to test for reliability of conclusions
P: Highly ethical
E: As participants are in a lab setting, it is likely they have given some sort of consent and fully debriefed after the study
E: This is a strength as it means no harm has happened to the ppts and ppts are likely to be happy to be used again, allowing new experiments to take place for psychology
WEAKNESSES:
P: Low in generalisability
E: Lab experiments often use a voluntary sample of participants, meaning they are likely to be more motivated and aware of what the experiment is testing for
E: This is a weakness because it means the sample being used is not very representative of the wider population, making results harder to generalise beyond the people in the study, and the ppts may show demand characteristics due to being more motivated, meaning the results are not generalisable beyond the people in the study.
P: Low in ecological validity
E: Lab experiments take place in a very artificial and controlled setting to the participants
E: This is a weakness because it means ppts behaviour may be influenced by the environment and behaviour may not be as natural or representative of the real world
P: Low mundane realism
E: Lab experiments may use tasks or tests which are not commonly found in the real world, for example Perterson and Peterson’s trigram recall test
E: This is a weakness because this task is not representative of how we’d use our memories in our everyday lives, therefore making it harder to generalise the findings from the stimulated task
What sort of environment does a FIELD experiment take place in?
-Natural/ real life surroundings, with the tasks being representative of real life
In a FIELD experiment, what control does the experimenter have over the different variables?
- can still manipulate the IV
- can still measure the DV but in a less detailed way
- low control over extraneous variables (especially situational ones)
- high chance of confounding variables
In a FIELD experiment, what is the participant selection like/ consist of?
-sampling may be random or opportunity due to natural environment, ppts aren’t matched or screened
Evaluate the use of FIELD experiments for conducting psychological research.
STRENGTHS:
P: High reliability
E: Field experiments do still use standardised procedures and all participants receive the exact same instructions in the same conditions
E: This is a strength because it means results are accurate and comparable
P: High ecological validity
E: Field experiments take place in a more natural and real life location, therefore the results can easily be generalised to these locations
E: This is a strength because it means that the ppts’ behaviours should be natural and very representative of the behaviour seen in everyday life (less chance of demand characteristics), giving accurate results
WEAKNESSES:
P: Low generalisability
E: Field experiments often use opportunity sampling of ppts available at the time of research, which is biased
E: This is a weakness because the sample isn’t representative of the wider population, making results harder to generalise to a wider population
P: Low reliability
E: Field experiments have a lower amount of control over extraneous variables such as noise, weather etc
E: This is a weakness because it means the IV and DV don’t have as reliable or trustworthy cause and effect relationship, making it difficult to prove the effect of the IV on the DV
P: Lower internal validity
E: In a field experiment there is some degree of control over extraneous variables, but it is significantly less then in a lab experiment
E: This is a weakness as we can’t confidently establish a cause and effect relationship between the IV and DV
P: Lower then Lab in ethics
E: Ppts may not be aware they are taking part in the research of a field experiment, breaching the fully informed consent guideline
E: This is a weakness as ppts may wish to withdraw due to not wanting their privacy breached, leading to less results to use
