EXPERIMENTAL METHOD

• REMEMBER: METHODS/TYPES ARE DIFFERENT FROM DESIGNS  
• An experiment that involves the manipulation of the IV to measure the effect on the DV – measures cause and effect – causal relationship
• Lab experiment - true

  1. Takes place in a controlled or lab environment 
  2. Researcher manipulates the IV 
  3. Records effects of IV on DV 
  4. Control of all other (extraneous) variables 
• Strengths of lab experiments

  • High control over extraneous and confounding variables (high internal validity – measure what should be measuring) 
  • Replication is easier  
• Limitations of lab experiments

  • Lacks generalisability (low external validity) 
  • Demand characteristics 
  • Low mundane realism – artificial surroundings 
• Field experiments - true

  1. Real life setting 
  2. Researcher manipulates IV and records DV effect 
  3. Participants natural setting so more natural behaviour 
  4. Stooges/confederates/actors placed in real life environment 
• Strengths of field experiments

  • Higher mundane realism (more natural environment) 
  • Produces more authentic and real behaviour 
  • Participants may be unaware of study (high external validity) 
• Limitations of field experiments

  • Harder to control CVs and EVs due to increased realism 
  • Cause and effect may be more difficult to establish, and precise replication is difficult 
  • Ethical issues as unaware of study 
• Natural experiment - not true

  1. Pre-existing IV – no manipulation by researcher 
  2. IV would've changed regardless of research and DV may be naturally occurring 
  3. Records effect of IV on DV (e.g. effects of covid on mental health)  
• Strengths of natural experiments

  • Opportunity for research that may not otherwise happen for practical or ethical reasons 
  • High external validity (real life problems) 
• Limitations of natural experiments

  • Limits generalisability 
  • Participants may not be randomly allocated to conditions (only applies to IGD) 
  • Other factors may influence the DV so cannot be sure of the IV effect 
• Quasi experiments - not true

  1. IV is based on existing difference between people  
  2. IV cannot be changed or manipulated by the researcher 
  3. DV may be naturally occurring or devised by experimenter in lab or field 
  4. Effect of gender (F/M) on memory or effect of age (old/young) on memory 
• Strengths of quasi experiments

  • Controlled conditions (shared strengths with lab) 
  • Replication is easier 
• Limitations of quasi experiments

  • Cannot randomly allocate participants to conditions – may be CVs 
  • IV is not deliberately changed to no way of knowing whether the IV has caused any observed changes 
• True experiments - involves manipulation of IV
• Not true experiments - no manipulation of IV