7.4: Control Conditions and Manipulation Checks

• Experimental Condition


  The condition in which the treatment is administered.
• Control Condition

  The condition in which the treatment is not administered.
• No-Treatment Control Condition


  In an experiment, a group of/or condition in which the participants do not receive the treatment being evaluated.
• A treatment versus no treatment experiment eliminates the independent variable; however...

  The researcher still creates treatment conditions by manipulating different values of the treatment variable. The no treatment condition is simply a zero value of the independent variable.
• Placebo Control Conditions

  A condition in which participants receive a placebo instead of the actual treatment.
• The Placebo Effect

  A participant's response to an inert medication or treatment that has no real effect on the body; occurs simply because the individual thinks the placebo is effective.
• Nocebo

  An inert substance that produces a negative or harmful effect simply because an individual expects or believes it will happen.
• What are the two types of research investigators differentiate due to the placebo effect?

  1. Outcome Research
  2. Process Research
• Outcome Research

  Investigates the effectiveness of a treatment. The goal is to determine whether a treatment produces a substantial or clinically significant effect. It is concerned with the general outcome of the treatment rather than identifying the specific components that cause the treatment to be effective.
• Process Research

  Attempts to identify the active components of the treatment. In process research, it is essential that the placebo effect be separated from other, active components of the treatment.
• Why is it important to know that using a control condition and the control extraneous variables are two completely different aspects of an experiment?

  Control of extraneous variables is an essential component of all experiments and is required to prevent extraneous variables from becoming confounding variable and threatening the internal validity of the study.
• Manipulation Checks

  In an experiment, an additional measure used to assess how the participants perceive and interpret the manipulation and/or to assess the direct effect of the manipulation.
• What are the two ways to check the manipulation?

  1. A manipulation check may be an explicit measure of the independent variable.
  2. A way to check the manipulation is to embed specific questions about the manipulation in a questionnaire that participants complete after their participants in the experiment.
• What are four times in which manipulation check is important?

  1. Participant Manipulations
  2. Subtle Manipulations
  3. Placebo Control
  4. Simulations
• Participant Manipulation

  Although researchers can be confident of the success of environmental manipulations, there is good reason to question the success of manipulations that affect the participants.
• Subtle Manipulation


  The variable being manipulated is not particularly salient and may not be noticed by the participants.
• Placebo Control


  The effectiveness of a placebo depends on its credibility. A manipulation check can be used to assess the realism of the placebo.
• Simulations


  The researcher attempts to create a real-world environment by manipulating elements within the experimental situation. A manipulation check can be used to assess how participants perceive and respond to an attempted simulation.