Although experiments typically manipulate some aspect of the environment to create different treatment conditions, it is also possible to manipulate characteristics of the participants. For example, researchers can give some participants a feeling of success and others a feeling of failure by giving false feedback about their performance or by rigging a task to make it easy or impossible (Thompson, Webber, & Montgomery, 2002). By manipulating the participants' experiences, it is possible to examine how people's performance and attitudes are influenced by success and failure. Other research has manipulated the participants' mood. Showing movies, playing music, or having participants read a series of positive (or negative) statements can induce different mood states (positive, negative, neutral). Being able to manipulate mood in the laboratory allows researchers to study how mood influences behaviors such as memory (Teasdale & Fogarty, 1979) or the ability to read emotions in facial expression (Bouhuys, Bloem, & Groothuis, 1995), and how other factors such as alcohol consumption affect mood (Van Tilburgh & Vingerhoets, 2002). Suppose you are planning a research study in which you intend to manipulate the participants' mood; that is, you plan to create a group of happy people and a group of sad people. For example, one group will spend the first 10 minutes of the experiment listening to upbeat, happy music, and the other group will listen to funeral dirges.
a. Do you consider the manipulation of people's moods to be ethical? Explain why or why not.
b. Would you tell your participants about the mood manipulation as part of the informed consent process before they begin the study? Explain why or why not.
c. Assuming that you decided to use deception and not tell your participants that their moods are being manipulated, how would you justify this procedure to an IRB? What could you do to minimize the negative effects of manipulating people's moods (especially the negative mood group)?
d. How could ou determine whether the different kinds of music really infl uenced people's moods? (Note: This is called a manipulation check, and is discussed in Chapter 7