What are the 4 experimental methods?
- Laboratory
- Field
- Natural
- Quasi
What is the purpose of laboratory experiments?
To establish a cause and effect relationship between the IV and the DV
Where do laboratory experiments take place?
In a controlled environment so there are fewer extraneous variables such as noise and temperature
Describe the strengths of laboratory experiments
- Control of IV
- Accurate measurement of the DV (correct analysis of data)
- Control over extraneous variables which limits unwanted background variables which could effect the outcome of the experiment
- Limits confounding variables which limits any participant change
- Replication of results is possible using the same methods
Describe the limitations of laboratory experiments
- Lacks generalisability so can’t be applied to other situations
- Low ecological validity because its not a real world setting
- Demand characteristics mean that it doesn’t provide meaningful conclusions as people may act differently
- Low mundane realism as a lab isn’t a real world setting so people may act different
Describe field experiments
- Take place in a natural environment
- Basic scientific procedures are followed
Describe an example of a field experiment
The Subway Samaritan
- Passenger falls on the New York subway (38 drunk and 65 with a cane)
- Passengers were participants but they didn’t know and students amongst the public acted as observers
- The aim was to see what factors lead people to help someone
describe the strength of field experiments
higher ecological validity
describe the limitations of field experiments
- loss of control
- extraneous variables
- ethics - people don’t know they’re involved so they can’t consent
describe natural experiments
- researcher makes use of naturally occurring variables but they therefore can’t manipulate the IV
- they’re used to investigate topics that would be impossible r unethical to do in a lab/ the field
- e.g. the war in Finland
describe the strengths of natural experiments
- provides an opportunity for research that wouldn’t otherwise be possible
- high ecological validity
describe the limitations of natural experiments
- lacks generalisability
- lacks opportunity for study
- can’t randomly allocate participants to a condition
describe quasi experiments
- features of a lab experiment but the IV is a characteristic of the participant so therefore isn’t quite a ‘real’ experiment
- e.g. gender/age
describe the strengths of quasi experiments
- control of Iv
- accurate measurement of DV
- control over extraneous variables
- limits confounding variables
- replication of results is possible using the same methods
describe the limitation of quasi experiments
- can’t randomly allocate participants to a condition
