Experimental Methods 🔬 Flashcards
What is the one thing that all experimental methods have in common?
They are attempting to find a cause and effect relationship between an independent variable (IV) and dependant variable (DV), and to measure the extent of this effect.
What are the four different types of experiments?
- Laboratory experiment
- Field experiment
- Natural experiment
- Quasi-experiment
What are Laboratory Experiments?
Laboratory experiments are conducted under specified controlled conditions in which the researcher manipulates the independent variable (IV to measure the effect on the dependent variable (DV).
— The conditions are heavily controlled in order to minimise the effect of any extraneous variables, to prevent them from becoming a confounding variable which might adversely affect the DV.
— Participants will be aware that they are taking part in an investigation due to the contrived nature of the situation which may feel unlike real life.
EVALUATION : Laboratory Experiments
STRENGTH - EXTRANEOUS VARIABLES
P: A strength of laboratory experiments is the high degree of control over extraneous variables which can be achieved.
E: A researcher is able, in most cases, to prevent extraneous variables from becoming confounding variables which negatively affect the DV.
E: This provides a high degree of internal validity, allowing for conclusions about cause and effect to be drawn between the IV and DV.
LIMITATION - LACKS EXTERNAL VALIDITY
P: A limitation of laboratory experiments is that they can lack external validity.
E: The artificial nature of the environment in which the investigation is taking place means that the study can lack ecological validity.
E: This means that the findings of the study cannot always be generalised to setting beyond the laboratory as the task often lacks mundane realism and would not be everyday life occurrences.
L: Since participants know they are being investigated, their behaviour can also change in an unnatural manner, resulting in demand characteristics being seen.
OVERVIEW : Laboratory Experiments
> SETTING:
— Controlled conditions
> MANIPULATION OF IV:
— The researcher
> STRENGTHS:
— High levels of control - reduces risk of extraneous variables
— Standardised measures used, so is easily replicable (high reliability)
— Internal validity
> LIMITATIONS:
— Low ecological validity (does not generalise outside of setting)
— Low mundane realism - does not generalise to real life specifically
— Demand characteristics change behaviour
What are Field Experiments?
Field experiments are carried out in natural conditions, in which the researcher manipulates the independent variable (IV) to measure the effect on the dependent variable (DV).
— The ‘field’ is considered any location which is not laboratory.
— Participants in a field experiment typically do not know that they are taking part in an investigation, with a view to observing more natural behaviour.
EVALUATION : Field Experiments
STRENGTH - ECOLOGICAL VALIDITY
P: The natural setting means that field experiments often have a higher level of ecological validity, in comparison to laboratory studies.
E: This means that the results are more likely to be representative of behaviour witnessed in everyday life.
E: However, because the setting is more natural, there is less control over extraneous variables.
L: These can then become confounding variables and distort the findings, meaning a firm cause and effect relationship cannot be drawn since other factors could have had an impact on the DV, other than the IV.
LIMITATION - ETHICAL ISSUES
P: On the other hand, there are important ethical issues associated with field experiments.
E: Since participants are often unaware that they are participants in a psychological investigation, they cannot give informed consent to take part.
E: As such, the research may involve a breach of their privacy rights and a cost-benefit analysis will need to be conducted before proceeding with any study to ensure the perceived outcomes from the research will outweigh any personal costs to those involved.
OVERVIEW : Field Experiments
> Setting:
— Natural conditions
> MANIPULATION OF IV:
— The researcher
> STRENGTHS:
— Higher ecological validity + mundane realism
— Higher internal validity than natural/quasi
— Reduced demand characteristics
> LIMITATIONS:
— Lack of informed consent / deception
— Reduced control - higher risk of extraneous + confounding variables
— Reliability could be lowered, not as easily replicable
What are Natural Experiments?
In a natural experiment, the researcher does not manipulate the IV and instead examines the effect of an existing IV on the dependent variable (DV).
— This IV is naturally occurring, such as a floor or earthquake, and the behaviour of people affected is either compared to their own behaviour beforehand, when possible, or with a control group who have not encountered the IV.
— It is important to take mote that this is the IV which is natural in this type of experiment, and not necessarily the context in which the investigation is taking place, since participants could be tested in laboratory as part of the study.
EVALUATION : Natural Experiments
STRENGTH - HIGH EXTERNAL VALIDITY + LIMITATION - NO CONTROL
P: The naturally occurring IV means that natural experiments often have a high level of external validity, compared to laboratory and field experiments.
E: Natural experiments have high levels of ecological validity because they examine real-life world issues in a natural setting.
E: However, natural experiments have no control over the environment and subsequent extraneous variables, which means that it is difficult for the researcher to accurately assess the effects of IV on the DV.
L: It may be that a confounding variable has affected the results to cause and effect relationship must be drawn with extreme caution, if at all.
STRENGTH - METHODOLOGY
P: A strength of using natural experiments is the unique insights gained into real-life situation from using this methodology.
E: Investigating a natural occurring IV allows for research to be conducted in areas of psychology that could not be generated for ethical reasons or because of logistical and practical constraints.
E: However, a naturally occurring event that interests researchers may only occur very rarely.
L: This limits the opportunity to generalise the results to other similar events or circumstances.
OVERVIEW : Natural Experiments
> SETTING:
— Natural conditions
> MANIPULATION OF IV:
— IV is naturally occurring
> STRENGTHS:
— High ecological validity / mundane realism
— Reduced risk of demand characteristics
> LIMITATIONS:
— Lack of control - high risk of confounding variable
— Lacks internal validity
— Ethical issues eg. consent, deception
— Lack of reliability
What is a Quasi-Experiment?
Quasi-experiments also contain a naturally occurring independent variable (IV), but one which already exists. However, in this instance, the IV is a difference between people such as gender, age or a personality trait.
— The researcher examines the effect of this IV on the dependent variable (DV).
— Quasi-experiments do not have to be conducted in a natural setting, although they often area. They may also be conducted in a laboratory setting, under controlled conditions.
EVALUATION : Quasi-Experiment
LIMITATION - BIAS
P: A limitation of quasi-experiments is that participants cannot be randomly allocated to research conditions to remove the issue of bias in the procedure.
E: Since the IV is a naturally occurring difference between the participants, the level of IV to which they belong is pre-decided.
E: This means that psychologists will be less certain that the IV alone will have caused the effect which is measured through the DV, as other dispositional or environmental factors may have played a role in the outcome.
L: That being said, quasi-experiments allow researchers to compare different types of people easily to provide insight into similarities or differences between these groups which could not be ethically generated otherwise.
LIMITATION - METHODOLOGICAL ISSUES
P: Another limitation is that there are methodological issues associated with conducting quasi-experiments.
E: When quasi-experiments take place under natural conditions, there is no control over the environment and subsequent extraneous variables, making it difficult ro be sure that factors such as age, gender or ethnicity have affected the DV.
E: On the other hand, when quasi-experiments take place under laboratory conditions, the high level of control means that the research often lacks ecological validity, and the findings cannot always be generalised to real-life setting since behaviour may not translate outside of the research environment.
OVERVIEW : Quasi-Experiments
> SETTING:
— Controlled/natural conditions
> MANIPULATION OF IV:
— IV is a difference between people, exists as it is.
> STRENGTHS:
— Allows us to study variables we cannot otherwise do so
> LIMITATIONS:
— Lack of control - possibility of extraneous variables
— Cannot manipulate the IV so may not be able to study behaviours exactly as we want to
