types of experiment

Question 1

what are laboratory experiments?

Answer 1

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

Question 2

what the strengths of laboratory experiments?

Answer 2

• high control over confounding (CVs) and extraneous variables (EVs)
  > the researcher can ensure than any effect on the DV is likely to be the result of the IV
  > higher internal validity ie. we can be more certain about demonstrating cause and effect
• replication is more possible than in other types of experiments due to the high level of control
  > ensures that new extraneous variables are not introduced when repeating an experiment
  > checks the results of any study to see whether the finding is valid or a one-off

Question 3

what are the limitations of laboratory experiments?

Answer 3

• may lack generalisability
  > lab environment may be artificial, so in an unfamiliar context participants may behave in unusual ways so their behaviour cannot be generalised beyond the research setting (low external validity)
• participants are usually aware they are being tested in a lab experiment which may cause ‘unnatural’ behaviour
• low mundane realism
  > the tasks participants are asked to carry out in lab experiments may not represent everyday experience

Question 4

what are field experiments?

Answer 4

an experiment that takes place in a natural setting within which the researcher manipulates the IV and records the effect on the DV
> researcher goes to the participants’ usual environment

Question 5

what are the strengths of field experiments?

Answer 5

• higher mundane realism than lab experiments because environment is more natural
  > 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)

Question 6

what are the limitations of field experiments?

Answer 6

• loss of control of CVs and EVs
  > means cause and effect between the IV and 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 they are being studied they cannot consent to being studied and such research might constitute an invasion of privacy

Question 7

what are natural experiments?

Answer 7

an experiment where the change in 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
> the IV is natural, but the setting isn’t necessarily. the DV can also be naturally occurring or devised by experimenter

Question 8

what are the strengths of natural experiments?

Answer 8

• provides opportunities for research that may not otherwise be undertaken for practical or ethical reasons
  > st helena island introduction of TV (charlton et al. 2000)
• high external validity
  > involves the study of real-world issues and problems as they happen, such as the effects of a natural disaster on stress levels

Question 9

what are the limitations of natural experiments?

Answer 9

• naturally occurring events may only happen very rarely, reducing opportunities for research
  > may limit the scope for generalising findings to other similar situations
• in an independent groups design, participants may not be randomly allocated to experimental conditions
  > researcher high be less sure whether the IV affected the DV
• research conducted in a lab may lack realism and demand characteristics may be an issue

Question 10

what are quasi experiments?

Answer 10

experiments which have an IV that is based on an existing difference between people (eg. age and gender). no one has manipulated the IV; it simply exists. IV also cannot be changed
- DV can be naturally occurring or may be devised by the experiment and measured in the field or lab

Question 11

what are the strengths of quasi experiments?

Answer 11

• often carried out under controlled conditions
  > share some strengths with lab experiments eg. replication

Question 12

what are the limitations of quasi experiments?

Answer 12

• there may be confounding variables due to the fact that you cannot randomly allocate participants to conditions
• IV is not deliberately changed by the researcher so we cannot claim that the IV has caused any observed change