Variables

• Confounding variable

  a kind of EV but it varies systematically with the independant variable. difficult for the researcher to be sure of the origin of the impact of the DV
• Demand Characteristics

  cues from the researcher or from the situation that mey be interpreted by participants as revealing the aim of an investigation,
• Demand characteristic problems

  • may lead to participants changing their behaviours due to second guessing.
  • Will give the 'please you': participants go along with it to please the researcher. Or the 'screw you effect': participants will sabotage the experiment.
  • Lowers the internal validity of the researche
• Investigator Effects

  Any effect of the investigators behaviour ( concious or unconcious) on the reserache outcome. it is another type of EV.

  Avoidance: Double blind procedure
• Randomisation

  • Controls the effects of bias
  • reduces investigator effects
• Standardisation

  • using exactly the same procedure for all participants in a researche study.
  • improves internal validity
• Experimental Design

  The ways in which participants are used in experiments
• Independant groups design 


  When two seperate groups of participants experience two different conditions of the experiment.
• Repeated Measures

  All participants experience both conditions of the experiment

  Example: Each participant would experience condition A, Each participant would then later be tested again in condition B. Then the two mean scores from both conditions would be compared to see if there was a difference.
• Matched Pairs Design


  participants are paired together on variables relevant to the experiment.
• Counterbalancing


  controls the order of effects
• Internal validity

  Internal validity refers to the extent to which an experiment accurately measures the relationship between the independent variable (IV) and the dependent variable (DV), without being affected by confounding variables.
• External Validity

  External validity refers to the extent to which the results of a study can be generalized beyond the specific conditions of the research. This includes generalizing to other people, places, times, and situations.
• Extraneous Variables

  -Any variables that are not the IV that may affect the DV if it is not controlled. 'Unwanted variables'