experiment types

• laboratory experiments is any special (controlled) environment where variables can be easily controlled
• one strength of a laboratory experiment is high internal validity, as extraneous variables can be controlled. this means we can be confindent any observed change in the DV is due to the manipulation of the IV.
• a limit of laboratory experiments:

  participants may show high DCs. this reduced ecological validity of the research (realness)

  also, the IV and DV may be operationalised in a way that doesnt represent everyday experiences. this means the research lacks mundane realism.
• a field experiment is conducted in an ordinary environment for the participant. the IV is deliberately manipulated and the DV is measured. Participants are usually unaware that they have been studied.
• one strength of a field experiment is that it is more realistic than lab experiments as it is more like the real world and therefore there are less demand characteristics, which means their behaviour is more 'real' and the results have higher ecological validity
• a strength of a feild investigation is participants may be more relaxed in their usual experiment meaning their behaviour is more likely to reflect real life
• a limitation of a feild experiment is that extraneous variables could confound results due to the reduced control experimenters have over them in a non-artificial environment, which makes it difficult to find truly causal effects between IVs and DVs
• a limitation of a field experiment can be ethical issues if people are unaware they are being studied (no informed consent)
• a limitation of field experiments is precise replication of the experiment is difficult as it is difficult to replicate the exact conditions so they have poor reliability, unlike experiments (lab) where exact results can be recreated
• an example of a lab experiment is Loftus and Palmer (1974). their experiment investigated the effect of leading questions on memory. they controlled all the variables to see how the use of different descriptive words such as smashed and bumped affected the recall of events that participants had seen
• an example of a field experiment is Bickman (1974) he investigated the effect of perceived authority on a persons obedience. a man dressed in different ways asked members of the public to pick up their litter. people were more likely to comply when he was dressed as a police guard
• a natural experiment is when the IV occurs naturally because it would be impractical or unethical for the researcher to manipulate it. however, the DV may still be tested/measured
• the disadvantage of a natural experiment is less control over extraneous variables due to research taking place outside of the lab. this means it's difficult to establish. causal relationships
• a limitation of a natural experiment is this method can only be used where the conditions vary naturally, meaning results can not be replicated
• a quasi experiment is when the IV is a difference that already exists between participants e.g. sex, gender. it has not been manipulated by the researcher.
• quasi: testing pre-existing differences between people

  natural: IV is naturally occuring