Research methods

• laboratory experiments


  performed in a controlled environment, using standardised procedure, with participants randomly allocated to experimental groups
• laboratory experiments --> advantages

  • higher degree of control --> all variables controlled and the IV and DV are precisely operationalised and measured, leading to greater accuracy and objectivity
  • replication --> other researchers can repeat to check results
  • cause and effect --> the effect must be caused solely by the manipulation of the IV as all other variables are controlled
  • isolation of variables --> individual pieces of behaviour can be isolated and vigorously tested
• laboratory experiments --> disadvantages

  • experimenter bias --> experimenters expectations can affect the results and participants may be influenced by these expectations
  • problems operationalising the IV and DV --> to gain precision measurements can become too specific and not relate to wider behaviour.
  • low external (ecological) validity
  • demand characteristics
• field experiments

  occur in 'real world' settings rather than the lab.

  the IV is manipulated by the experimenter and as many other variables as possible are controlled

  • try to show cause and effect
  • try to control variables
• field experiments - advantages

  • reliable
  • low demand characteristics
  • high ecological validity
• field experiments - disadvantages

  • hard to replicate as conditions are never exactly the same again
  • bias - Ps are not randomly allocated to groups
  • ethics - Ps are not aware that they are in an experiment - lack of informed consent
• natural and quasi experiments

  natural --> IV varies naturally; the experimenter does not manipulate, but records the effect on the DV (romanian orphans)

  quasi --> the IV occurs naturally, such as in the study of gender where males and females are compared

  • natural and quasi experiments are often used when it is unethical to manipulate an IV. in such studies random allocation of Ps is not possible
• natural and quasi experiments- disadvantages

  • very low reliability
  • no control of variables so cant manipulate them
  • hard to replicate
  • sample bias
• natural and quasi experiments- advantages

  • highest validity (ecological)
  • low demand characteristics