Types of experiment

• Lab experiments-

  • Takes place in a controlled and artificial environment.
  • Helps have contour over extraneous variables.
  • Not always in a lab, can be in a classroom, but it’s just set up and monitored with high control by the investigator. (Milgram, Zimbardo, Asch).
• Lab experiments- Strengths

  • S- High control of extraneous variables- changes of the DV can only be due to the IV making the results more certain – high internal validity.
  • S- Easily replicated without extraneous variables affecting the replication (essential to check validity).
• Lab experiments- Weaknesses

  • W- Lacks generalisability- artificial environment, unfamiliar setting may cause the participants to act unusually, results can’t be generalised to the outside world (lacking external validity).
  • W- Participants are aware that they are being observed – demand characteristics.
  • W- Tasks may not represent real life, making the experiment lack mundane realism.
• Field experiments-

  • Natural setting (school, street, workplace).
  • Direct control over the IV.
  • Participants are directly allocated to conditions.
  • Can be replicated.
  • Allows casual relationships to be detected.
• Field experiments-

  • S- High mundane realism due to the real environment.
  • S- May produce behaviour that is more real and natural – valid and authentic.
  • W- Loss of control over extraneous variables – not controlled environment.
  • W- Harder to identify cause and effect.
  • W- Harder to replicate- hard to test validity.
• Field experiments-

  • CPS- Participants may not know that they’re being studied – high external validity.
  • CPW- Ethical issues – if they are unaware of the experiment they can’t consent and may have privacy issues and are unable to withdraw or be debriefed.
• Natural experiments-

  • Naturally occurring event for research purposes.
  • Doesn’t directly manipulate the IV due to being naturally occurring.
  • IV would naturally change without the experiment.
  • Can be conducted in a lab.
• Natural experiments-

  • S- Research areas that may not have been able to be studied- ethical and practical.
  • S- High external validity due to often being related to real life issues whilst they happen.
  • W- Can’t be randomly allocated due to needing to be observed.
  • W- Differences may be due to the participants not the IV.
  • W- Hard to know which aspect of the IV causes the effect on behaviour.
• Quasi experiments-

  • Have IV based on existing differences that occur between people (IV hasn’t been changed).
  • Can’t randomly allocate groups (experimenter is less sure if the IV affects the DV).
  • IV can’t be changed, the DV may be naturally occurring/made.
• Quasi experiments- evaluations

  • S- Often carried out under controlled conditions (alike to lab experiments).
  • S- High internal validity.
  • S- Can be replicated.
  • W- Can’t randomly allocate participants to conditions.
  • W- Possible confounding variables.
  • W- IV isn’t deliberately changed, so can’t claim that it has caused any change.