Social Interaction Threats
What are “Social” Threats?
Applied social research is a human activity. And, the results of such research are affected by the human interactions involved. The social threats to internal validity refer to the social pressures in the research context that can lead to posttest differences that are not directly caused by the treatment itself. Most of these threats occur because the various groups (e.g., program and comparison), or key people involved in carrying out the research (e.g., managers and administrators, teachers and principals) are aware of each other’s existence and of the role they play in the research project or are in contact with one another. Many of these threats can be minimized by isolating the two groups from each other, but this leads to other problems (e.g., it’s hard to randomly assign and then isolate; this is likely to reduce generalizability or external validity). Here are the major social interaction threats to internal validity:
Diffusion or Imitation of Treatment
This occurs when a comparison group learns about the program either directly or indirectly from program group participants. In a school context, children from different groups within the same school might share experiences during lunch hour. Or, comparison group students, seeing what the program group is getting, might set up their own experience to try to imitate that of the program group. In either case, if the diffusion of imitation affects the posttest performance of the comparison group, it can have an jeopardize your ability to assess whether your program is causing the outcome. Notice that this threat to validity tend to equalize the outcomes between groups, minimizing the chance of seeing a program effect even if there is one.
Here, the comparison group knows what the program group is getting and develops a competitive attitude with them. The students in the comparison group might see the special math tutoring program the program group is getting and feel jealous. This could lead them to deciding to compete with the program group “just to show them” how well they can do. Sometimes, in contexts like these, the participants are even encouraged by well-meaning teachers or administrators to compete with each other (while this might make educational sense as a motivation for the students in both groups to work harder, it works against our ability to see the effects of the program). If the rivalry between groups affects posttest performance, it could maker it more difficult to detect the effects of the program. As with diffusion and imitation, this threat generally works to in the direction of equalizing the posttest performance across groups, increasing the chance that you won’t see a program effect, even if the program is effective.
This is almost the opposite of compensatory rivalry. Here, students in the comparison group know what the program group is getting. But here, instead of developing a rivalry, they get discouraged or angry and they give up (sometimes referred to as the “screw you” effect!). Unlike the previous two threats, this one is likely to exaggerate posttest differences between groups, making your program look even more effective than it actually is.
Compensatory Equalization of Treatment
This is the only threat of the four that primarily involves the people who help manage the research context rather than the participants themselves. When program and comparison group participants are aware of each other’s conditions they may wish they were in the other group (depending on the perceived desirability of the program it could work either way). Often they or their parents or teachers will put pressure on the administrators to have them reassigned to the other group. The administrators may begin to feel that the allocation of goods to the groups is not “fair” and may be pressured to or independently undertake to compensate one group for the perceived advantage of the other. If the special math tutoring program was being done with state-of-the-art computers, you can bet that the parents of the children assigned to the traditional non-computerized comparison group will pressure the principal to “equalize” the situation. Perhaps the principal will give the comparison group some other good, or let them have access to the computers for other subjects. If these “compensating” programs equalize the groups on posttest performance, it will tend to work against your detecting an effective program even when it does work. For instance, a compensatory program might improve the self-esteem of the comparison group and eliminate your chance to discover whether the math program would cause changes in self-esteem relative to traditional math training.
As long as we engage in applied social research we will have to deal with the realities of human interaction and its effect on the research process. The threats described here can often be minimized by constructing multiple groups that are not aware of each other (e.g., program group from one school, comparison group from another) or by training administrators in the importance of preserving group membership and not instituting equalizing programs. But we will never be able to entirely eliminate the possibility that human interactions are making it more difficult for us to assess cause-effect relationships.