Types of Experiment, Chapter 6, 4 Flashcards
What is a laboratory experiment?
An experiment that takes place in a controlled environment within which the researcher manipulates the IV and records the effect on the DV, whilst maintaining strict control of extraneous variables
What is a field experiment?
An experiment that takes place in a natural setting within which the researcher manipulates the IV and records the effect on the DV
What is a Quasi-experiment?
A study that is almost an experiment but lacks key ingredients. The IV has not been determined by anyone (the researcher or any other person)- the ‘variables’ simply exist, such as being old or young. Strictly speaking, this is not an experiment. DV may be naturally occurring or devised by the experimenter and measured in the field or a lab
Where are lab experiments conducted?
In highly controlled environments. This is not always a laboratory it could be a classroom where conditions can be well-controlled
What are the strengths of lab experiments?
They have high control over confounding and extraneous variables.
Replication is more possible than in other types of experiment because of the high level of control
What does lab experiments having high control over confounding and extraneous variables mean?
This means that the researcher can ensure that any effect on the dependent variable is likely to be the result of manipulation of the independent variable
Thus, we can be more certain about demonstrating a cause and effect (high internal validity)
What lab experiments having an increased possibility of replication mean?
This ensures that new extraneous variables are not introduced when repeating an experiment.
Replication is vital to check the results of any study to see whether the finding is valid and not just a one-off
What are the limitations of laboratory experiments?
Lab experiments may lack generalisability
The participants are usually aware they are being tested in a lab experiment (though they may not know why) giving rise to unnatural behaviour due to demand characteristics
The tasks participants are asked to carry out in a lab experiment may not represent everyday experience (e.g. recalling unconnected lists of words as part of a memory experiment ( low mundane realism))
What does lab experiments maybe lacking generalisability mean?
The lab environment may be rather artificial and not like everyday life. In an unfamiliar context participants may behave in unusual ways so their behaviour can not always be generalised beyond the research setting (low external validity)
What are the strengths of field experiments?
They have a higher mundane realism than lab experiments because the environment is more natural. Thus field experiments may produce behaviour that is more valid and authentic. This is especially the case as participants may be unaware they are being studied (high external validity)
Why do field experiments have a higher mundane realism than lab experiments?
Because the environment is more natural. Thus field experiments may produce behaviour that is more valid and authentic. This is especially the case as participants may be unaware they are being studied (high external validity)
What are the limitations of field experiments?
There is a price to pay for increased realism due to the loss of control of CVs and EVs, this means cause and effect between the IV and the DV in field studies may be much more difficult to establish and precise replication is often not possible
Important ethical issues, if participants are unaware that they’re being studied, they cannot consent to being studied and such research might constitute an invasion of privacy
What does increased realism in field experiments mean?
This means cause and effect between the IV and the DV in field studies may be much more difficult to establish and precise replication is often not possible
What is a natural experiment?
An experiment where the change in the IV is not brought about by the researcher but would have happened even if the researcher had not been there. The researcher records the effect on a DV they have decided on
What are strengths of a natural experiment?
They provide opportunities for research that may not otherwise be undertaken for practical or ethical reasons, such as the studies of institutionalised Romanian orphans (Rutter, et al)
They often have high external validity because they involve the study of real-world issues and problems as they happen, such as the effects of a natural disaster on stress levels
What are the limitations of a natural experiment?
A naturally occurring event may only happen very rarely, reducing the opportunities for research.
This may also limit the scope for generalising findings to other similar situations
Another issue: participants may not be randomly allocated to experimental conditions(only applies where there is an independent groups design). This means the researcher might be less sure whether the IV affected the DV. Such research may be conducted in a lab and therefore may lack realism and demand characteristics may be an issue
What does natural experiments not randomly allocating participants mean?
This means the researcher might be less sure whether the IV affected the DV. Such research may be conducted in a lab and therefore may lack realism and demand characteristics may be an issue
What is an example of the issues faced by natural experiments not randomly allocating participants?
For example, in the study of Romanian orphans, the IV was whether children were adopted early or late. However there were lots of other differences between these groups such as those who were adopted late may also have been less sociable than some of the other children which may have made them less appealing for prospective parents
What are the strengths of a quasi-experiment?
They are often carried out under controlled conditions and therefore share some strengths of a lab experiment (e.g. replication)
What are the limitations of a quasi-experiment?
Like natural experiments , we cannot randomly allocate participants to conditions and therefore there may be confounding variables
Also like in natural experiments, the IV is not deliberately changed by the researcher and therefore we cannot claim that the IV has caused any observed change
