experimental method

Experimental Method

  • Definition: The experimental method involves the manipulation of an independent variable (IV) to measure the effect on a dependent variable (DV). This method is fundamental in psychological research.

Key Terms

  • Aims: A general statement of what the researcher intends to investigate, which describes the purpose of the study.
  • Hypothesis: A clear, precise, testable statement that states the relationship between the variables to be investigated, formulated at the outset of any study.
    • Directional Hypothesis: A hypothesis that states the direction of the anticipated difference or relationship between two groups (e.g., "more," "less," "higher," "lower").
    • Non-Directional Hypothesis: A hypothesis that does not specify the direction of the difference or relationship but states that there is a difference.
  • Variables: Anything that can vary or change within an investigation.
    • Independent Variable (IV): Some aspect of the experimental situation manipulated by the researcher, or changes that occur naturally, allowing for measurement of effects on the DV.
    • Dependent Variable (DV): The variable that is measured by the researcher, where any effect should be caused by changes in the IV.
    • Operationalisation: The process of clearly defining variables in terms of how they can be measured.

Application of the Experimental Method

Investigating Energy Drinks and Talkativeness
  • Initial Theory: Energy drinks affect how much people talk; based on research that indicates sugar and caffeine in energy drinks increase alertness and chattiness.
  • Specific Hypothesis: After identifying the theory, a specific aim can be formulated: "To investigate whether drinking energy drinks makes people more talkative."
  • Formulating a Hypothesis: The hypothesis can be formed as: "Drinking SpeedUpp causes people to become more talkative."
    • Directional Hypothesis Examples:
      • "People who drink SpeedUpp become more talkative than those who don't."
      • "People who drink water are less talkative than those who drink SpeedUpp."
    • Non-Directional Hypothesis Example:
      • "People who drink SpeedUpp differ in terms of talkativeness compared to people who don't drink SpeedUpp."

Conducting the Experiment

  • Procedure: Two groups of people will be gathered for the experiment: 10 participants will receive SpeedUpp and 10 will receive water. After consumption, the researcher will record how many words each participant says in a five-minute period.
  • Considering Types of Hypothesis:
    • Researchers usually choose a directional hypothesis based on previous theories or research suggesting an expected outcome.
    • The effects of caffeine and sugar are well-documented, leading to the decision to opt for a directional hypothesis in this investigation.

Writing Hypotheses

Study Tips
  • Formulating Clear Hypotheses: To create an effective hypothesis, ensure:
    1. The IV and DV are clear and measurable.
    2. The relationship between the IV and DV is explicitly stated, not mistaken for aims.
    3. The appropriate type of hypothesis (directional or non-directional) is selected based on given information.

Variables in Experiments

Manipulation of IV
  • In any experiment, a researcher manipulates the IV and measures its effects on the DV.
  • Control of Variables: All other variables should remain constant in a properly run experiment to ensure that changes in the DV are a result of the IV alone.

Levels of the IV

  • To analyze the effects of the IV, different experimental conditions are required:
    • Comparison between participants' talkativeness before and after drinking SpeedUpp.
    • Comparison between participants drinking SpeedUpp and those consuming water.
  • Conditions:
    • Control condition (water): No SpeedUpp.
    • Experimental condition (energy drink): Drinking SpeedUpp.

Operationalisation of Variables

  • Clear operationalisation is crucial to establish a testable hypothesis.
    • Revised Better Hypothesis:
      "After drinking 300 ml of SpeedUpp, participants will say more words in the next five minutes than participants who drink 300 ml of water."
    • The operationalisation clarifies the specifics for measurement and research outcomes.

Practice Applications and Questions

  1. Create Aims and Operationalise Variables: For various scenarios, define the IV and DV, and develop both directional and non-directional hypotheses.

    • Examples include investigating confidence levels in obedience, effects of a new drug on anxiety, the contagiousness of yawning, effects of goldfish ownership on well-being, and social behaviors related to hair color.

  2. Determine Hypotheses: Recognize if the provided hypotheses are directional or non-directional by identifying key features or wording.

    • Distinguish between differences depending on eye color, treatment effects with dogs, psychology grades based on gender, and the impact of horror films on friendships.

  3. Identify IVs and DVs: Practice identifying the IV and DV in various behavioral scenarios, such as the effect of conversing with children or temperature influence on aggression.

Understanding Hypotheses

  1. Difference between Aims and Hypotheses: Understand that aims are broader statements of investigation purpose, whereas hypotheses are precise, testable relationships involving specific variables.

    • Example: "To investigate whether energy drinks affect talkativeness" (aim) vs. "Drinking SpeedUpp increases talkativeness" (hypothesis).

  2. Operationalise Key Concepts: Explore methods for operationalising constructs such as memory, physical activity, and intelligence for measurable outcomes.

  3. Reasons for Non-Directional Hypotheses: Reflect on situations that may lead researchers to opt for non-directional hypotheses, such as the absence of established theories or conflicting previous findings.

End of Notes