Want to reduce aggression in adolescents? Work on their beliefs

Want to reduce aggression in adolescents? Work on their beliefs
27 March 2013

Teenagers sometimes believe that bullies will always be bullies and victims will always be victims. An intervention teaching young people that other people really can change improved adolescents’ behavior and reduced conduct problems, a recent US study found.

Adolescence is a period when young people develop stronger beliefs in the fixed nature of personal characteristics, particularly aggression. This can make teens resistant to interventions that successfully reduce aggression in children.

Some adolescents believe that people’s traits are fixed and people who are “bullies” or “victims,” “winners” or “losers,” cannot change. These adolescents are likely to respond vengefully to bullying situations where they are victims. They are likely to wish to “get back at” peers who had insulted or excluded them, and to dream of ways to “give them what they deserved.”

Other adolescents, however, believe that people have the power to change. These adolescents are less likely to want to get back at their peers who have bullied, insulted or excluded them. Instead, they are likely to be more hopeful about their future and more understanding of wrongdoers.

In a recent study, a group of US researchers tested what would happen if they taught adolescents that people don’t have fixed personalities and that they are capable of changing. Could teens learn to apply this knowledge to conflict situations with peers? Would it reduce the aggressive desire to return like for like? The test showed promising results.

The current experiment

The study tested the effect of a six-session, school-based intervention. The program taught an “incremental theory” – that is, the idea that personal change is possible.

In a large, diverse San Francisco area high school, 230 students aged 14-16 were randomly assigned to a six-session incremental theory intervention or to one of two control groups. One control group received six sessions of instruction in social-emotional coping skills. The other control group received no treatment. The effects of the intervention were measured two weeks, one month, and three months after the program ended.

Before the trial, many students clearly felt that there were problems in the school: on a survey administered by the school, “70% of students did not agree that students treat each other with respect, and 40% said that they did not feel safe from threats at school.”

The interventions were delivered in biology classes: students were randomly assigned to one of nine biology classes, and then three of the nine classes were assigned to each of the conditions.

Both the intervention focusing on incremental theory and the coping skills intervention lasted three weeks and involved six 50-minute class sessions. There were two teams of facilitators, who were randomly assigned to train in and then to deliver either the incremental theory intervention or the coping skills intervention.

The two interventions were similar in many ways. The activities students completed, the texts they read, and the lectures they heard were similar or identical for much of the workshops. However, the main intervention taught the participants the idea that “people have the potential for change, especially in the context of victimization or exclusion.” The control group intervention taught “skills for thinking positively and coping productively in the face of victimization or exclusion.”

The main findings: The way young people think about others affects aggression

Compared to no-treatment and coping skills control groups, the incremental theory group behaved significantly less aggressively and more prosocially one month after the intervention. Furthermore, teachers reported fewer conduct problems for the intervention group three months after the intervention.

Interestingly, both the intervention group and the coping skills control group adolescents showed fewer depressive symptoms among those who reported being victimized by their peers.

These findings suggest that teaching adolescents that people have the potential to change could be successful in reducing levels of aggression, conduct problems and depression for racially and socioeconomically diverse students.

However, the authors say, “It is important to note that the ultimate goal of research in this area is to find ways to reduce bullying and victimization in general, and not only to help students cope with instances of victimization.”



Yeager, D. S., Trzesniewski, K. H., & Dweck, C. S. (2012). An implicit theories of personality intervention reduces adolescent aggression in response to victimization and exclusion. Child Development. DOI: 10.1111/cdev.12003


randomized controlled trials

Sometimes referred to as experimental evaluations, randomized controlled trials or RCTs randomly allocate potential beneficiaries of an intervention to a program or treatment group (who receive the intervention) or a control group (who do not). Outcomes for the two groups are then compared.

They are most often used to test medicines or medical procedures, but they are becoming more common in social interventions, particularly in relation to early years programs and education interventions in the US.

RCTs are considered the most reliable way of testing the effect of an intervention on outcomes for the potential beneficiary. Since the subjects of a trial are allocated at random to program and control groups, both are statistically equivalent and comparisons of outcome will reflect the effect of the intervention and not the characteristic of the groups.

Most importantly, RCTs eliminate selection effects. For example, if entry to the program tested was not random, the outcome might be the result of one group wanting the intervention more than another.

RCTs are strong at estimating the size of the difference in predefined outcomes between program and control groups. It is possible, therefore, to estimate how much change is the result of the intervention.

Other evaluation designs, including quasi-experimental designs that include a control group can detect associations between an intervention and an outcome but they cannot rule out the possibility that the association was caused by a third factor linked to both.

Incremental theory

 People hold different theories about the nature of individual characteristics such as personality or intelligence. People holding an incremental theory think of individual characteristics as malleable qualities that can be developed. See also “entity theory.”

Entity theory

 People hold different theories about the nature of individual characteristics such as personality or intelligence. People holding an entity theory believe that individual characteristics are unchangeable, fixed “entities”. See also “incremental theory.” 

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