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Hallmarks of True Experimental Approaches

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In experimental approaches, participants are randomly assigned to conditions in which one or more variables of interest have been manipulated. There is an attempt to control extraneous variables and to measure as many potential third variables as necessary. The outcomes you measure test the effect of these manipulations. As an example, in Devlin et al. (2013), participants (students and adults from the community) viewed one of four photographs of the office of a psychotherapist that varied in the kind of art displayed (Western vs. Multicultural) and the number of art objects on view (1 vs. 6). Participants were randomly assigned to one of the four conditions generated by crossing the two art traditions (Western vs. Multicultural) with the two different numbers of art objects (1 vs. 6) (see Figure 3.1).

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Figure 3.1 Four Types of Photographs Displayed in a Psychotherapist’s Office

Source: Copyright © 2013 by the American Psychological Association. Devlin, Borenstein, Finch, Hassan, Iannotti, and Koufopoulos, 2013. Multicultural art in the therapy office: Community and student perceptions of the therapist. Professional Psychology: Research & Practice, 44, 168–176. The use of this information does not imply endorsement by the publisher.

Between-subjects design: Research in which the conditions of an experiment are distributed across participants such that each participant is in only one condition.

Within-subjects design: Type of experimental design in which participants are exposed to all of the conditions.

Participants answered a series of questions about the characteristics of the therapist whose office they viewed; the office was created for the purposes of the research. The research question was whether the display of art that differed in (a) cultural tradition and (b) number of art objects would impact participants’ judgments of therapists, in particular, their openness to multiculturalism. This experimental approach is called a between-subjects design because the conditions are distributed between (across) participants. In the between subjects approach, each person participates in only one condition. This approach is often used because the researcher is concerned that participating in more than one condition would produce different results than participating in a single condition and that the impact of a given condition could not be isolated. Moreover, the between subjects approach reduces the likelihood that participants will guess the hypothesis of the research. In contrast, in the experimental approach called a within-subjects design, all participants would have seen all four photographs; that is, they would have been exposed to all of the conditions. Researchers often select a within-subjects design when (a) effects of participating in one condition on another are unlikely or (b) there are such effects that carry over and researchers want to study them. Between- and within-subjects approaches are covered in more depth in Chapters 9 and 10, respectively.

The Research Experience

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