Psya1 Research Methods :
Strengths and Weaknesses Of Experimental Designs
Laboratory Experiments
In laboratory experiments researchers conduct the experiment in a specially controlled setting. Researchers control all the variables except the Independent variable (IV) which is the thing that is changed between the experimental conditions. Whatever effect the Independent variable has is called the dependant variable (DV). Participants are usually always aware of being observed however they may not necessarily know “what” is being measured.
Strengths Of Laboratory Experiments
- There is a high level of control which means that extraneous variables can be minimised and with less outside influences. As the only thing being changed between laboratory conditions is the Independent variable (IV), researchers can be more certain that the dependent variable (DV) they see are changes to the independent variable (IV) rather than anything else.
- Laboratory experiments have high internal validity as the high level of control and the altering of only the Independent variable (IV) between conditions allows researchers to be more sure they are measuring what they wish to measure.
- Changes to the IV make it possible to measure the effect on the DV. This allows cause and effect statements to be made and relationships established between two variables established.
- Laboratory experiments are easier to replicate and repeat to check the reliability of findings as procedures are standardised.
- Laboratory experiments allow researchers to create and measure experiments that would normally be difficult to set up or observe in real life.
Limitations/Weaknesses Of Laboratory Experiments
- Laboratory experiments may result in people behaving in an unnatural way different to what they would really be like in real life settings. Some tasks in laboratory experiments may be contrived hence the resulting behaviours may lack internal validity and not be indicative of real life.
- Participants are aware they are being observed and this could lead to demand characteristics and participants behaving in a way that is not representative of true behaviour. Therefore laboratory experiments may lack internal validity as the behaviour being measured is not the real behaviour.
- Laboratory experiments lack ecological validity and realism due to the artificial setting.
- Researchers involved in the experiment may result in experimenter effects where their own expectations influence the participants behaviour.
Field Experiments
Field experiments are controlled experiments which are conducted usually in everyday environments outside the laboratory. The independent variable (IV) is still manipulated by researchers and the effect on the dependent variable (DV) is measured. The main difference here is that field experiments tend to be more “natural”. Participants may or may not be aware of being observed in field experiments with behaviour believed to be more natural than laboratory experiments generally.
Strengths Of Field Experiments
- Field experiments have higher ecological validity as they tend to be conducted in more natural settings.
- Field experiments allow researchers to measure more natural behaviour in people due to the more natural environment. Therefore the findings may have high internal validity as the behaviour observed may be more “real” than in laboratory settings.
- When participants are unaware of being observed this helps minimise the risk of demand characteristics.
- There is still some control over environment and manipulation of the independent variable is still possible. This allows researchers to make statements about cause and effect.
Limitations/Weaknesses Of Field Experiments
- There is less control over field experiments compared to lab experiments meaning extraneous variables might affect the independent variable (IV) or dependent variable (DV). This means researchers cannot always be certain that changes to the DV are due to changes in the IV.
- Replication of field experiments are harder and therefore it is more difficult to check the reliability of findings.
- Ethical issues arise when participants are not aware of being observed as part of a study and therefore there is deception occurring. Informed consent may not always be possible either which breaches ethical guidelines.
- If participants are aware of being observed demand characteristics are still possible from participants.
Natural Experiments
Natural experiments are experiments where the independent variable (IV) is naturally occurring and is not manipulated by the researcher. Participants may or may not be aware of being observed.
Strengths Of Natural Experiments
- Natural experiments allow researchers to measure things that may be unethical to set up in a laboratory e.g. adoption studies or smoking effects.
- When participants are unaware of being observed the behaviour is high in internal validity and more realistic as demand characteristics are minimised.
- Natural experiments have high ecological validity as the settings are much more natural.
Weaknesses/Limitations Of Natural Experiments
- Natural experiments are harder to replicate meaning the reliability of findings cannot be checked.
- There is no control over the experiment by researchers as they merely observe. This means a number of extraneous variables could be contributing to the DV resulting in low internal validity. This makes it difficult to infer cause and effect.
- There is no control over the allocation of participants between conditions. Therefore individual differences are harder to control for.
- If participants are unaware of being observed this raises ethical issues as informed consent is not gained.
Saj Devshi
Jedi Master at Loopa
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