1. “Social Interaction” Threats to Internal Validity

2. What Are “Social” Threats?
All are related to social pressures in the research context, which can lead to posttest differences that are not directly caused by the treatment itself.
Most of these can be minimized by isolating the two groups from each other, but this leads to other problems (for example, hard to randomly assign and then isolate, or may reduce generalizability).

3. Diffusion or Imitation of Treatment
Controls might learn about the treatment from treated people (for example, kids in the school cafeteria).

4. Compensatory Equalization of Treatment
Diffusion or Imitation of Treatments
Compensatory Equalization
Compensatory Rivalry
controls compete to keep up with treatment group
Resentful Demoralization
controls "give up" or get discouraged

5. Compensatory Equalization of Treatment=
Diffusion or Imitation of Treatments
Compensatory Equalization
Compensatory Rivalry
controls compete to keep up with treatment group
Resentful Demoralization
controls "give up" or get discouraged
Administrators give a compensating treatment to controls.

6. Controls compete to keep up with treatment group.
Compensatory Rivalry
Compensatory Rivalry
Resentful Demoralization
controls "give up" or get discouraged
Controls compete to keep up with treatment group.

7. Resentful Demoralization
Controls "give up" or get discouraged.
The “screw you” effect.