• Experimental method. Types of experiment, laboratory and field experiments; natural and quasi- experiments.
AO1 for natural experiment
A natural experiment is conducted when it is not possible for the researcher to deliberately manipulate the IV. Therefore it is said that the IV varies 'naturally' The DV can be measured in a laboratory.
AO3 for laboratory experiment
A strength is the control the experimenter has over the research, therefore they are contrived. It is high in internal validity because we can be certain that any observed change in the DV is because of the IV. A limitation is that they are often low in ecological validity, it is not just because of the controlled environment, it is also because the participants know they are being studied which is likely to affect their behaviour. The low ecological validity can be explained in terms of the setting. The operationalisation of the variables and the setting is described as being low in mundane realism. People behave more like they 'normally' do when a study is high in mundane realism. Therefore participants in a lab experiment are less likely to behave as they would in everyday life. The IV or DV may also be operationalised in a way that isn't applicable to real life such as film clips to test eyewitness memory.
What is a Quasi experiment?
An experiment in which the IV is not manipulated by the researcher, it is the characteristic of a person, e.g gender.
What is a laboratory experiment?
An experiment that is conducted in a highly controlled environment.
AO1 for Laboratory experiment What it is Participants awareness what they involve.
An experiment that is conducted in a highly controlled environment. Participants are aware they are in an experiment however the contrived nature of the experiment may cause the participants to alter their behaviour because they know it is being recorded. Laboratory experiments also often involved artificial materials such as consonant syllables, this makes the experience less like everyday life.
What is a Field experiment?
An experiment that is conducted in a more natural environment.
What is a natural experiment?
An experiment which the researcher has not deliberately manipulated the IV.
AO1 for Field experiment
It is similar to a laboratory experiment in that the IV is still deliberately manipulated by the researcher and the DV is still measured. A key feature is that the participants are usually not aware that they are participating in an experiment therefore their behaviour may be more natural.
AO3 for Field experiment?
The IV in a field experiment may lack realism therefore field experiment are not necessarily more like everyday life than lab experiments. They tend to be more natural but it is more difficult to control extraneous variables. There is also an ethical issue- if participants don't know they are being studied and it is difficult to debrief the, there are ethical issues with manipulating and recording their behaviour.
AO1 for Quasi experiment
The IV is naturally occurring and the DV can be measured in a lab. The IV has not been made to vary by anyone. It is simply a difference between people that exist
AO3 for natural experiment
The lack of control over the IV means that we cannot say for certain that the change in the DV was purely due to the IV. For example if there were uncontrolled confounding variables then observed changes in the DV may not be due to the IV. Casual conclusions can only be tentatively drawn. independent group design, participants are randomly allocated to conditions. The lack of random allocation means there may be uncontrolled confounding variables.
AO3 for Quasi experiment
independent group design- Lack of random allocation means that there may be uncontrolled confounding variables. Casual conclusions can only be tentatively drawn.