Types of experiments

• Lab experiment

  • A controlled experiment
  • participants are aware they are taking part in an experiment.
  • The researcher deliberately manipulates (changes) the independent variable
• Field Experiment

  • An experiment conducted in a more natural environment.
  • The researcher would go to the participants 'usual environment'.
  • participants are not usually aware they are participating in an experiment.
• Natural experiment

  • The researcher still measures the effect of an Iv on a DV.
  • However the experimenter makes use of a natural IV.
  • The setting may not be natural, but the IV is something the researcher cannot manipulate/change e.g. natural disaster.
• Quasi Experiment

  • Has an IV based on existing difference between people e.g. age, gender, phobia, medical conditions and learning disability.
  • No one has manipulated this variable it already exists.
• Lab Experiment- Strengths

  • High control
  • high internal validity as you can establish a cause and effect relationship
  • replicable- can be tested for reliability
• Lab experiment- Weakness

  • Lacks ecological validity (external vaidity) this leads to findings cannot be easily generalised
  • low mundane realism
  • risk of demand characteristics
• Field experiment-Strengths

  • High ecological validity ( external validity) this means it can be easily generalised
  • High mundane realism
  • less of a risk of demand characteristics
• Field experiments- Weaknesses

  • No high control
  • Low internal validity
  • May not be replicable
  • low reliability, ethical issues
• Natural experiments- Weaknesses

  • Ethical issues
  • Events occur rarely
• Quasi experiments

  • Casual relationships are not demonstrated
  • Researcher does not manipulate the IV so therefore, we cannot say for certain that and change in the DV was due to the IV.
  • Participants are not randomly allocated- participant variables