Types of experiments Flashcards
(13 cards)
What is a laboratory experiment?
An experiment that takes place in a highly controlled environment within which the researcher manipulates the IV and records the effect of the dv, whilst maintaining strict control of extraneous variables
(These are not always in a lab, they could be in a classroom where the conditions are well-controlled)
What are some strengths of laboratory experiments?
- There is a high degree of control over extraneous variables, preventing them from affecting the DV
- Replication is easier because of the high levels of control
- High degree of internal validity
Give some limitations of laboratory experiments
- They can lack generalisability - the lab is artificial and not like everyday life
- Participants may behave in unusual ways because they know they are being tested - low external validity and demand characteristics
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 of the DV
Participants are not usually aware they are taking part in the study
What are some strengths of field experiments?
- High levels of ecological validity and authentic- the results are more likely to be representative of behaviour witnessed in real life
- More natural environment- results may be more generalisable to everyday life
Give some weaknesses of field experiments
- Less control over extraneous variables - This means that cause and effect between the IV and the DV may be more difficult to establish
- Replication is often not possible
- Ethical issues- if participants are not aware that they are being studied they cannot consent
Could become an invasion of privacy
What is a natural experiment?
An experiment where the change in the IV is not brought about by the researcher but would have happened if the researcher had not been there. The researcher records the effect on the DV they had decided on
Researcher has no control over the IV- it’s natural and they cannot change it e.g. Bowlby’s maternal deprivation and Romanian orphanages studies- these were things that would have happened anyway and the researcher just decided to study it
Participants may still be tested in a lab
The DV may also be naturally occurring but could also be devised by the experimenter- an IQ study that compares football players to rugby players
What are some strengths of natural experiments?
- These provide opportunities for research that may not otherwise be undertaken for practical or ethical reasons (e.g. Romanian orphans)
- They have high external validity because they involve the study of real-world issues and problems e.g. effects of natural disasters on stress
What are some limitations of natural experiments?
- A naturally occurring event may happen rarely, reducing opportunities
- Participants may not be randomly allocated, therefore the researcher may be less sure whether the IV affected the DV
- This research can be conducted in a lab and therefore lacks realism and demand characteristics may be an issue
What is a quasi-experiment
A study that is almost an experiment but lacks key ingredients. The IV has not been demonstrated by anyone (the researcher or any other person)- the ‘variables’ simply exist, such as being young or old. Strictly speaking this is not an experiment
The IV is pre-existing (e.g. age, gender)
No one has manipulated the variables they simply exist
As with natural experiments, the DV may be naturally occurring or may be devised by the experimenter and measure in the field or a lab
What are some strengths of quasi-experiments?
- Quasi experiments are carried out under controlled conditions
- Allows researchers to compare different types of people to look into similarities and differences (gender, ethnicity)
Give some limitations of quasi-experiments
- Participants cannot be randomly allocated- the researcher could be bias
- Because the IV is naturally occurring, psychologists cannot be sure that the IV alone caused the effect on the DV
What are the 4 different types of experiments?
Laboratory experiment, field experiment, natural experiment and quasi-experiment
