Types of experiment

• Laboratory experiment

  • A experiment which takes place in highly controlled conditions
• Laboratory experiments - internal validity - :)

  1. High control over confounding and extraneous variables
  2. Ensures that the results of the DV are due to manipulation of the IV
  3. Allows for the researcher to establish a clear cause and effect relationship
  4. Increases internal validity
• Laboratory experiments - Replication - :)

  1. Replication more possible with lab experiments compared to all others due to the high levels of control
  2. Ensures no new extraneous variables are introduced during replication.
• Laboratory experiment - Genralisability - :(

  1. Laboratory experiments often lack genralisability
  2. Lab experiments are highly artificial and unlike everyday life
  3. Behaviour may not be able to be generalised outside research setting - low external validity
• Laboratory experiments - Demand characteristics - :(

  1. In most laboratory experiments participants are usually aware they're being tested
  2. This may mean that they were behaving in unnatural ways - demand characteristics
  3. Furthermore, the tasks may not be represent everyday life
  4. low mundane realism
• Field experiment

  • An experiment which takes place in a natural setting
  • The researcher goes to the participants usual environment
  • Setting is more like everyday
• Field experiment - :)

  1. Higher mundane realism compared to laboratory experiments because environment is more natural
  2. Therefore, field experiment may produce behaviour that is more valid and accurate
  3. Participants are unaware they're being studied
  4. Higher external validity
• Field experiments - Low internal validity :(

  1. Increased realism means loss of control over confounding and extraneous variables
  2. A cause and effect relationship between the IV and DV may not be possible
  3. May be much more difficult to establish cause and effect relationship
  4. Lower internal validity
• Field experiment - ethical issues - :(

  1. Participants in natural environments may be unaware they're being studied
  2. Unable to give informed consent
  3. Research may also be an invasion of privacy
  4. Rises important ethical issues
• Natural experiments

  • A experiment where the experimenter does not need to manipulate the IV.
  • The change in the IV would have occurred even if researcher had not been there
• Natural experiment - Unique - :)

  1. Provides opportunities for research that may other wise be unethical or impractical to conduct
  2. E.g research into Romanian orphans
• Natural experiments - external validity - :)

  1. Research involves the study of real-world issues and problems as they happen
  2. Increases external validity
• Natural experiments - Reduced research - :(

  1. A naturally occurring even may only happen rarely reducing the opportunities for research
  2. This limits the scope of generalisation to other similar situations
• Natural experiments - random allocation - :(

  1. Participant's can not be randomly allocated to experimental conditions
  2. Therefore, there may be differences between the groups studied
• Quasi experiments

  • An experiment where the IV is based on a existing difference between people
  • Placed in groups based on things they already have in common
  • This might be age, gender phobias or depression
• Quasi experiment - :)

  1. These experiments are often carried out under controlled conditions
  2. Share majority of the strengths of a laboratory experiments - replication
• Quasi experiment - :(

  1. Random allocation of participants may not occur - may be confounding variables
  2. The IV has not been manipulated by the researcher therefore changes observed in the DV may not be due to the IV