Types of Experiments in Psychology

Experiments Types

• Laboratory Experiments:
  • Artificial setting
  • High levels of standardization
  • Tight control
  • Independent and dependent variables present
  • Aim to control extraneous variables, but this can be difficult
• Field Experiments:
  • Participants in natural setting
  • Independent variable manipulated
  • Dependent variable also measured
  • Attempt to control extraneous variables, but it can be difficult
  • More room for situational variables impacting the dependent variable

Problems with Laboratory Experiments

• Unnatural situations
• The more extraneous variables controlled, the less realistic the experiment becomes
• Manipulation of independent variable may not cause the change in dependent variable
• (Experiment) is unnatural and therefore doesn't generalize to real life.

Problems with Field Experiments

• Can't control all variables affecting the dependent variable
• Real-life situations are chaotic, which limits clear cause & effect
• Difficult to conclude that the manipulated variable necessarily caused the measured effect

Validity

• Validity:
  • A study is valid if it accurately represents what it intends to represent.
  • Experimental validity refers to how variables influence results and generalizability to the population.
  • Validity also refers to how well a test measures what it was designed to measure.
• Internal Validity:
  • How well a study establishes a cause-and-effect relationship
  • Crucial for determining if a treatment/intervention caused an outcome
• External Validity:
  • How well the study’s findings can be applied to other settings
  • How generalisable the results are to real-life situations
• Ecological Validity:
  • Extent to which the findings of a study can be generalised to real-life settings
  • Particularly useful for understanding how behaviors manifest in familiar contexts

Research Question Example

• Do violent video games make people more violent?

Evaluation of Experiment

• High Internal Validity, Low External Validity: Experiments can accurately measure the effect of video games on aggression, but the artificial situation might not reflect real-world reactions.

Spectrum of Experiments

• There is a spectrum of experimental methodologies.
• Laboratory experiments have high internal validity, but often lack external validity.
• Field experiments have higher external validity, but often lower internal validity.
• Natural experiments are often high external validity but often lack internal validity.

Triangulation

• Psychologists use various methods (e.g. different types of experiments, interviews) to analyze research questions—this is known as triangulation.

Homework

• Review material on validity and types of experiments,
• Focus on identifying subjective and objective aspects of research.
• Note different types of validity (internal, external)
• Note Generalizability- demand characteristics
• Note strengths and weaknesses of different experiment types (lab & field)

Strengths and Weaknesses of Lab Experiments

• Strengths: High standardization, replicability, high control over extraneous variables, confident the IV affects the DV
• Weaknesses: Artificial setting, tasks are often not real-life (lack mundane realism) participants know they're in an experiment (demand characteristics)

Strengths and Weaknesses of Field Experiments

• Strengths: Realistic settings, high ecological validity, participants are typically unaware, reduces demand characteristics
• Weaknesses: Difficulty controlling situational variables, uncertain if the IV is causing the effect or another uncontrolled variable, difficulty establishing cause/effect relationships. ethical issues (like informed consent)

This quiz explores different types of experiments used in psychology, focusing on laboratory and field experiments. It examines the strengths and weaknesses of each method, including issues with controlling variables and the generalizability of results. Test your knowledge on experimental design and its implications for psychological research.