How Can A Nurturing Environment Reduce Bias, Prejudice and Conflict Between Groups?

The classic experiment that shows this happened in the 1950s, the Robbers Cave study (Sherif, Harvey, Hood, Sherif, & White, 1988).  An excellent 3-minute video summarizes how this classic experiment worked, which you can view at  Now that study happened more than 60 years ago with some middle-class boys in state park by the name of Robbers Cave in Oklahoma.  The experiment happened in three stages:

  • Stage one: The boys were randomly assigned to two groups, and never knew about the other group for a week. During the first week, each “team” (self named as the Rattlers or the Eagles), bonded together with fun camp activities.
  • Stage two: The two groups were brought together physically for week, and given competitive tasks for scarce resources. Hard feelings, name calling, conflict, and retribution started to happen between the two groups.
  • Stage three: The experimenters arranged common tasks for the kids to solve such fixing the water supply supposedly caused by vandals.  More and more activities were introduced that required them to work together to achieve a common, reinforcing goal. With that intervention, significant positive, pro-social behavior and cohesion happened among all the boys.

This study reveals the huge paradox in human behavior and evolution.  Human pro-sociality within groups (tribes, clans, etc.) evolved from threat from outside or other groups of humans. For us as a species, our gift of pro-social, nurturing behaviors evolved in context of external threats from the other. Since the invention of stone tools, humans became the principal predator of other humans, and other humans became our principal source of safety.

Appreciation of this paradox is necessary to create a more peaceful, nurturing environment for our children.  The PAX Good Behavior Game (see consciously acknowledges the paradox to create sustained positive, pro-social, and nurturing environments with long-term positive benefits.  Children are typically randomized to teams in the classroom, which are changed or rotated frequently. The children work to create a group reward for the whole class, which you can easily hear when students excitedly proclaim, “everybody won.”  How do we know that PAX really, cross your heart, pinky swear helps children be more pro-social, with less bullying, more positive or inclusive interactions with each and more successful? By measuring the impact.

How do we do that?

First, we measure disturbing, disruptive, aggressive, and/or inattentive behaviors using a standard minute-by-minute observation protocol. We teach local PAX Partners and community groups to collect such measures that get fed into our web-based data system. The system creates graphs of results, and if the predicted results don’t happen, we arrange a technical assistance call to find out why and provide strategies to meet unique needs. In most all of the cases, PAX GBG dramatically improves children’s behaviors rapidly.

Second, many implementing partners as teachers to fill out standardized surveys on children called the Strengths and Difficulties Questionnaire (visit The instrument is short and sweet, predictive of either lifetime risk or lifetime protection.

Third, we keep running new randomized longitudinal trials to test our assumptions and make improvements, since the world never stays the same. Right now, there are new studies with pre-service teachers, with early career teachers, in after-school programs, in the entire province of Manitoba, and more. Your community can easily test the value of creating a nurturing classroom environment with PAX GBG in your community, and we encourage you to do so.

Of course, there are our colleagues at Johns Hopkins continue to follow students who got what is PAX GBG 20 to 30 years ago, which produce new results each year like the report this December, 2013, showing that exposure to what is now PAX GBG caused the protective expression of Brain Derived Neurotropic Factor (BDNF) genes against mental illness (Musci, et al., 2013).  What all these studies show is that it possible for the findings of the Robber’s Cave study to be used to improve the well-being and futures of children, which is why the study was done in the first place.


Musci, R. J., Bradshaw, C. P., Maher, B., Uhl, G. R., Kellam, S. G., & Ialongo, N. S. (2013). Reducing aggression and impulsivity through school-based prevention programs: A gene by intervention interaction. Prevention Science, No Pagination Specified. doi: 10.1007/s11121-013-0441-3

Sherif, M., Harvey, O. J., Hood, W. R., Sherif, C. W., & White, J. (1988). The Robbers Cave Experiment: Intergroup Conflict and Cooperation. [Orig. pub. as Intergroup Conflict and Group Relations in 1954]. Middletown, CT: Westlyan Unversity Press.


About Dennis Embry

Since 1979, Dennis D. Embry, now president/senior scientist at PAXIS Institute in Tucson, AZ, has been designing, testing and disseminating interventions that prevent or reduce the risk from mental, emotional and behavioral disorders among children and youth in the United States and other countries. All of these interventions have dealt with a variety of troubling problems: issues of inattentive, disturbing, disruptive or impulsive behaviors, military deployments, or the effects of such behaviors (e.g., injuries, substance abuse, tobacco use, school failure, child maltreatment). Since the late 1990s, Dr. Embry’s papers and projects have integrated behavioral science, brain science and evolutionary theory to create effective practices and policies, particularly testing large-scale strategies for prevention. He is one of the few prevention scientists in the world to have conducted multiple population-level prevention efforts for communities, counties, states/provinces, tribes, or nations. For example, one of Dr. Embry’s NREPP cited efforts (Reward & Reminder) is the only scientifically proven environmental policy documented to produced state level prevention effects using a controlled study across multiple states. In the 1990s, he developed the largest youth violence prevention study in the US, called PeaceBuilders, with an implementation in more than 80 schools in Tucson with an embedded randomized-control trial and a community-wide social marketing campaign. In the early 1990s, Secretary of Defense hired Dr. Embry to recommend and implement protocols to help children and families of deployed military during the Gulf War and the efforts in Somalia, and to prevent or reduce trauma effects. In the 1980s, Dr. Embry worked with Sesame Street and, later, the Government of New Zealand on the first scientifically proven strategies to prevent one of the leading causes of death to preschool age children: being struck by a car while playing outside. Today, Dr. Embry and his colleagues at PAXIS Institute: 1) deliver prevention services all over the country and help private and public entities set up prevention services, 2) teach public and private entities how to improve the quality of those services and measures results, 3) promote prevention strategies for the large and small business in communities, and 4) develop and map prevention to multiple systems in the public and private sectors internationally. Dr. Embry and his colleagues are also technical assistance and training providers for 38 SAMHSA sites using the PAX Good Behavior Game. Dr. Embry’s work is being widely implemented in the United States, Canada, First Nations (Native American Tribes) with new projects beginning in Ireland, Estonia, New Zealand and Australia.

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