Types of experiments? Flashcards
What are the 4 types of experiments?
- Lab
- Field
- Natural
- Quasi
What is a laboratory experiment
These are conducted in highly controlled environments within which the researcher manipulates the IV and records the effects on the DV whilst maintaining strict control of extraneous variables.
Strengths for a laboratory experiment?
Have high control over confounding and extraneous variables. This means that any effect on the DV is likely to be the result of manipulation of the IV.
Easy to establish cause and effect, meaning it has high internal validity.
Easy for others to replicate, as the high degree of control ensures that new extraneous variables are not introduced when repeating the experiment. This means it has high reliability
Limitations for a laboratory experiment?
Lack generalisability as the environment may be rather artificial and not like everyday life, meaning it has low external validity.
Experiments are of a greater risk to demand characteristics, as participants are usually aware they are being tested in a lab experiment and this may give rise to ‘unnatural’ behaviour.
Tasks participants are asked to carry out in a lab may not represent everyday experience, so it lacks mundane
realism.
What are field experiments?
Take place in a natural, more everyday setting within which the researcher manipulates the IV and records the effects on the DV. The researcher goes to the participants’ usual environment.
Strengths of field experiments?
Higher mundane realism because the environment is more natural.
Produces behaviour that is more valid and authentic. This is especially the case as participants may be unaware they are being studied, high external validity.
As behaviour is more natural, this means that participant behaviour is not being influenced by demand
characteristics.
Limitations of filed experiments?
There is a loss of control of confounding and extraneous variables. This means cause and effect between the IV and the DV may be much more difficult to establish.
Field studies are very difficult to replicate.
There are important ethical issues. If participants are unaware they are being studied they cannot consent and such research might constitute an invasion of privacy.
What are natural experiments?
The researcher measures the effect of an IV on a DV. However, what distinguishes a natural experiment is the researcher has no control over the IV and cannot change it. The DV is simply measured and judged as the effect of an IV. Rutter’s research investigating the effects of institutionalisation on Romanian orphans.
Strengths of natural experiments?
Provide opportunities for research that may not otherwise be undertaken for practical or ethical reasons, such as Rutter’s Romanian orphan research.
Have high external validity because they involve the study of real-world issues and problems as they happen.
High levels of mundane realism. The environment and tasks are similar to what would happen in real life since it is real life.
Limitations for natural experiments?
These studies lack generalisability as naturally occurring events may only happen very rarely, reducing the opportunities for research.
Participants may not be randomly allocated to experimental conditions meaning that the researcher might be less sure whether the IV affected the DV.
Because the IV is naturally occurring the researcher will have less chance of isolating extraneous variables.
What are quasi experiments?
V that is based on an existing difference between people (e.g. age or gender). No one has manipulated this variable, it simply exists. In quasi experiments, participants are not randomly assigned to conditions or order of conditions. They automatically fit into a particular category.
Strengths for quasi experiments?
As quasi experiments tend to be conducted in a lab, there is some degree of control over extraneous variables. This means that any effect on the DV is likely to be the result of manipulation of the IV.
Easy to establish cause and effect, meaning it has high internal validity.
Easy for others to replicate, as the high degree of control ensures that new extraneous variables are not introduced when repeating the experiment. This means it has high reliability.
Limitations for quasi experiments?
Cannot randomly allocate participants to conditions, meaning there may be confounding variables.
The IV is not deliberately changed by the researcher and therefore we cannot claim that the IV has caused any observed change to the DV.
