EXPERIMENTAL METHOD

Laboratory experiment

  • An experiment carried out in a controlled environment
  • All situational variables are controlled
  • Participants are aware they are in an experiment, but might not know the aims
  • Participants are randomly allocated to each condition (when appropriate) so that the experimenter has no control over which participants are in each condition, reducing bias

Strengths:

Weaknesses:

  • One variable can be manipulated (IV)

  • High level of control over EVs – high internal validity
  • Reliably establish cause and effect (change in the DV due to the manipulation of the IV)
  • Can be replicated (high external validity) as they are highly scientific
  • May not represent behaviour in a real life setting: Lacks ecological validity and mundane realism (as they know they are being studied)
  • Participants are likely to know that they are taking part in an experiment and may alter their behaviour due to demand characteristic (participant effects)
  • Control causes artificial setting

Mundane realism

  • Lab experiments lack mundane realism
  • Mundane realism = how a study mirrors the real every world day

Field experiment

  • An experiment carried out in the natural environment
  • Some situational variables are controlled
  • The IV is manipulated by the experimenter
  • In most (but not all) – participants are unaware they are taking part, which reduces problems like demand characteristics

Example

  • Hofling et al (1966) – pg 198
  • IV – order over the phone from ‘Doctor smith’ to give a patient 20mg of Astroten
  • DV – whether they gave the patient the drug or not
  • 21 out of 22 nurses did as they were told

Strengths

  • IV can be manipulated
  • Some control over EVs
  • Participants in natural environment, so findings likely to represent what you’d usually find in a real life setting: More ecological validity.
  • Avoids demand characteristics (as they are not aware)

Weaknesses

  • Confounding variables are more likely, so cause and effect may be less reliable – less internal validity
  • More time consuming
  • Participants may not know they are being studied = ethical issues