Types of experiments

• Lab experiments

  In a controlled lab

  Strength: control over extraneous variables

  Weakness: artificial tasks so demand characteristics lowering ecological validity
• Field experiments

  In natural setting

  Strength: generalise to real world & high ecological validity

  Weakness: low control over extraneous variables so lowered internal validity
• Natural experiment's

  Researcher uses pre-existing IV e.g. Romanian orphans are already orphans

  Strength: opportunity to research IV that may normally be unethical

  Weakness: lack of control over other variables e.g. what they experienced
• Quasi experiments

  IV is based on pre existing difference between people & its never been changed its always existed e.g. age or gender

  Strength: same as lab

  Weakness: confounding variables because no random allocation, they already exist in groups