Diffusion of Intervention Effects
As a developmental methodologist, I was trained to design evaluations so as to avoid contamination effects, in which individuals in the treatment group impact individuals in the control group. Yet outside of the research context, such “contamination” is desirable, as it represents the diffusion of intervention effects from participants to non-participants. This diffusion of intervention effects through participants’ social networks can increase the reach and sustainability of intervention programs. Such diffusion may be particularly likely when the targeted behaviors are influenced by the normative social context (e.g., substance use) and when the behaviors involve dyadic relationships (e.g., sexual intercourse). For example, if one partner changes his or her normative beliefs about condom use after participating in an intervention, then he or she may insist on using a condom, thereby changing the behavioral outcome of partners who did not participate in the intervention. It is also possible that gender may alter the dynamics: Given the power differential within heterosexual partnerships, it is possible that diffusion may be more or less likely depending on the gender of the partner who participated in the intervention.
Read more about some of my work in this area in the Reuters Health article "Teens may not drink or smoke if friends are counseled not to" and in the NIDA Notes article "Prevention Program Reduces Substance Use By Participants' Friends"
Read more about some of my work in this area in the Reuters Health article "Teens may not drink or smoke if friends are counseled not to" and in the NIDA Notes article "Prevention Program Reduces Substance Use By Participants' Friends"
Resources for those interested in diffusion of intervention effects
Diffusion of Innovations Research:
Rogers, E.M. (2003). Diffusion of Innovations. New York: Free Press.
Classic overview of Diffusion of Innovations Theory. This book provides a great mix of research, theory, and case
examples that are great "cocktail party" trivia (For example, read this book to find out what Paul Revere, the QWERTY
keyboard, photovoltaic lights, the internet, and corn all tell us about diffusion processes!)
Valente, T. W. (1995). Network Models of the Diffusion of Innovations. Cresskill, NJ: Hampton Press.
Valente, T. W., Gallaher, P., & Mouttapa, M. (2004). Using social networks to understand and prevent substance use: A
transdisciplinary perspective. Substance Use & Misuse, 39, 10-12.