experimental methods

• 4 types

  • lab
  • field
  • natural
  • quasi
• Lab AO1

  An experiment conducted in a lab which is a highly controlled environment, where the researcher manipulates the independent variable (IV) and measures the effect on the dependent variable (DV)
• Lab A03

  STRENGTHS

  • High level of control over extraneous variables, cause and effect can be established, increases internal validity
  • High in reliability, easily repeated in same conditions to check for consistent results
• LAB AO3

  LIMITATIONS

  • Lacks Ecological validity, difficult to generalise the findings, lowering the external validity.
  • prone to demand characteristics, ppts change normal behaviour based on clues given off by researcher, ppts help or hinder the researcher, reducing internal validity
• Field A01

  An experiment which takes place in a natural environment (for the ppts) such as an office or school, where the researcher manipulates the independent variable (IV) and measures the effect on the dependent variable (DV)
• FIELD A03

  STRENGHTS

  • Less prone to demand characteristics, might not know they are being watched, less likely to guess clues given off by the researcher and change their natural behaviour, increases internal validity
  • High ecological validity, easier to generalise the findings, increases external validity
• FIELD AO3

  LIMITIONS

  • Low in reliability, difficult to repeat with exactly the same conditions to check for consistent results.
  • ethical issue of lack of informed consent, not aware they are being studied, become aware may become upset and wish to withdraw their data from the research
• NATURAL A01

  The researcher takes advantage of a naturally occurring IV (EVENT). This is a natural experiment because the variable would have changed even if the experimenter was not interested.
• NATURAL A03
• NATURAL A03

  STRENGHTS

  • High ecological validity ,real life setting therefore it is easier to generalise the finings, increasing external validity
  • Natural experiments provide opportunities, may not be undertaken for practical or ethical reasons, natural experiments contribute to a greater psychological understanding of behaviour.
• NATURAL A03

  LIMITIONS

  • Low control over extraneous variables, difficult to establish cause and effect between the IV and the DV, lowering the internal validity of the study.
  • Naturally occurring event may only happen very rarely, which limits opportunities for research, unlikely that the research can be repeated to check for consistent results so lacks reliability.
• QUASI A01

  An experiment which has an IV based on an existing individual difference between people (characteristic), which the researcher has not manipulated e.g. age or gender, and the researcher measures the effect on the DV
• QAUSI AO3

  LIMITIONS

  • Sample bias as the sample being studied may have unique characteristics (E.G), difficult to generalise to the target population, decreasing the external validity of the study