Experimental Designs for Relationship Research

Experimental Designs

The main focus of experimental research methods is on how different social or situational contexts influence people's responses (e.g., their thoughts, feelings, or behaviors). In a basic experiment, the researcher introduces a treatment to one group of participants (i.e., the experimental group) and withholds treatment to another group of participants (i.e., the control group). Critically, all study participants are randomly assigned to each group, helping ensure that participants in each group do not differ, on average, in any meaningful way from each other. Additionally, all study procedures are identical across the groups except for the treatment introduced by the researcher. The researcher then assesses all participants on the same dependent variable(s) of interest, and compares the scores from participants in the experimental and control groups to determine if the treatment had the intended effect. Any differences that emerge between participants placed into the experimental or control conditions are attributed to the treatment rather than extraneous factors. The control of extraneous factors and the isolation of key experimental manipulations allow the researcher to make cause and effect conclusions, which is the major benefit of experimental methods.

To illustrate the implementation of an experimental design in relationship research, consider a study conducted by Clive Seligman and colleagues that tested the hypothesis that in the context of a committed romantic relationship people would feel more love for their partners when they perceived their own motives for being with their partners as intrinsic (i.e., enjoying the qualities of their partners for their own sake) rather than extrinsic (i.e., enjoying the qualities of their partners because they serve other ends). Couples participating in this research were randomly assigned to one of three treatment conditions. Participants were asked to complete a number of open-ended sentences containing either the prepositional phrase because I (e.g., I seek out my girlfriend/boyfriend because I …), or in order to (e.g., I seek out my girlfriend/boyfriend in order to …). Prior research had shown that the phrase because I established an intrinsic mindset and the phrase in order to established an extrinsic mindset. In a third (control) condition, participants simply completed the set of dependent variables. The primary dependent variable was the degree to which participants reported loving their partner, assessed after the experimental treatments had taken effect. Compared with people in the control and intrinsic motivation conditions, people in the extrinsic motivation condition reported lower levels of love for the partner when led to believe that they were with their partner as a means to achieve other ends. No mean differences in reported love emerged, however, between the control and intrinsic motivation conditions. The use of an experimental design allowed the researchers to conclude that an extrinsic motivation for maintaining a romantic relationship caused people to feel less love for their partners.

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