types of experiments

• laboratory experiment:

  researchers can easily manipulate the IV for an outcome on DV

  in controlled setting

  usually artificial

  participants know they are being studied but dont know aim
• what are the strengths of lab experiment?

  high in internal validity

  control of extraneous variables as control setting

  easy to replicate

  demand characteristics likely
• what are the limitations of lab experiment ?

  lacks mundane realism

  low in external validity so cannot be generalised

  low in ecological validity

  demand characteristics
• field experiment:

  more natural setting

  participants dont know being studied
• what are the strengths of a field experiment?

  high in external validity

  less likely for demand characteristics

  high in ecological validity

  high in mundane realism

  easier to generalise findings
• what are the limitations of field experiment?


  extraneous variables more likely

  low in internal validity

  confounding variables more likely

  unethical

  harder to replicate
• natural experiments:

  iv varies naturally without the manipulation of researcher as unethical to do so but DV still can be tested in lab

  researchers just measure the change

  e.g romanian orphans
• what are strengths of natural experiments?

  high in ecological + external validity

  allow study of real life situation

  high in mundane realism

  cannot be replicated
• quasi experiment:

  where the iv doesnt vary

  just a difference in characteristics between participants
• strengths of quasi experiment?


  only way to study certain factors that are pre existing characteristics of participants
• limitations of quasi experiment?

  other factors such as confounding variables could have changed with IV and so changed the DV
• what is investigator effects/bias?

  anything investigator does that could effect participants performance

  can be indirect or direct
• ways of dealing with investigator effects:

  • single blind = participants unaware of some details of experiment
  • double blind = both participants and investigator dont know the aim of the study
  • experimental realism= experimenter makes tasks more engaging to maintain participants attention to tasks not to the fact they being observed