Experiments

• The experimental method has a high level of control over EV and manipulation of the IV. They include lab experiments and field experiments
• Non experimental methods have a low level of control. It includes observations questionaries interviews and case studies
• Experiments begin with the creation of a hypothesis. The aim is to establish a cause and effect relationship between the iv and the dv whilst controlling as many ev as they can.
• The Hawthorne effect was a study in 1927 seeing how different lighting affected their work ethic. It didn't as they worked consistently as they knew they were being observed
• Most psychology experiments are social so the interaction between the experimenter and participants may have an effect on the dv (cofounding or extraneous)
• Examples of experimenter bias

  • operationalising in a way that prompts desired results
  • mis-recording results
  • influencing the behaviour of participants verbally or non verbally
  • Failing to follow procedures accurately
• Socially desirable - participants changing their behaviour for what they feel they OUGHT to be like
• The single blind - a way of controlling demand characteristics. Participants don't know the aim of the study. This brings some ethical issues like informed consent and deception
• The double blind - A way of controlling demand characteristics and experimenter effects. Participants and experimenters don't know the aim of the study
• Lab experiments

  • high level of control with manipulation of the iv
  • an example is the Loftus and palmer 1974 - where participants where shown a traffic accident then asked to recall details but with leading questions
• Lab experiment strengths

  • Good for cause and effect
  • Standardised procedures mean greater reliability
  • Objective quantitative data
• Lab experiments weaknesses

  • May be artificial (lack in ecological validity) therefore validity is lowered
  • Unlike real life
  • High experimenter effects
  • Demand characteristics
  • Ethical problems
• Field experiments

  • Where the researcher manipulates the IV but in a natural environment. little control over ev
  • An example is piliavin et al 1969 - An experiment to see the behaviour of people when a victim suddenly collapses. They did not know they were being studied
• Strengths of a field experiment

  • A high ecological value
  • Low demand characteristics
  • Objective quantitive data
• Weaknesses of field experiments

  • Low internal validity as results may be caused by something other than the iv
  • Low reliability
  • Experimenter effects
  • Lack of informed consent
  • High deception and no right to withdraw also an invasion of privacy
• Internal validity - the extent to which the test measures accurately what its supposed to