Using Implementation Intentions to Reduce Anger and Aggression in Adolescence

This study aims to test whether aggression in adolescents can be reduced using implementation intentions. This technique involves identifying critical situations that might trigger the unwanted behaviour and making a plan to engage in an alternative course of action when those triggers are present. Implementation intentions formation has been found to be effective in reducing smoking uptake and consultations for emergency contraception in this age group.

A randomised controlled trial will be conducted. Students from 11 to 17 years old attending special schools for children with behavioural problems or referred for anger issues will be randomised to three conditions: attention control, specific triggers and general trigger. Participants in the attention control and specific triggers conditions will receive the same Volitional Help Sheet (VHS), composed of a list of 10 anger triggers (if statements) and a list of 10 anger management strategies (then statements). However, the instructions will be different. Participants in the attention control condition will be instructed to select the triggers that they encounter more often and the strategies that they consider more useful. In contrast, participants in the specific triggers condition will have to link each specific trigger that they encounter often with a specific strategy, thus creating action plans with an if-then structure. Participants assigned to the general trigger condition will also be instructed to make plans linking the trigger with a strategy, but the VHS they will receive will contain only one general trigger: "If I am getting angry".

Measures of anger and reactive physical aggression, reactive relational aggression, proactive physical aggression and proactive relation aggression will be collected at baseline, one month and six months after intervention. In addition, measures of negative urgency, violent intentions and callous-unemotional traits will be collected once.

Both intervention groups are hypothesised to reduce anger and reactive aggression in comparison to the control group. It is hypothesised that the reduction in anger acts as a mediator for the reduction of reactive aggression. It is also hypothesised that violent intentions, callous-unemotional traits and negative urgency act as moderators of effectiveness.

The effects of the intervention will be analysed on anger, on the aggression total score and on the four types of aggression separately using Multivariate Analysis of Covariance. In order to test whether the effect of the interventions on reactive aggression at follow-up is mediated by anger, a mediation analysis will be conducted using the PROCESS macro (Hayes, 2013). In the analysis, the intervention conditions (dummy coded) will be entered as the independent variable, anger as the mediator variable, reactive aggression at follow-up as the dependent variable, and reactive aggression at baseline as the covariate. The analysis will asses the strength of the direct and indirect effects of the interventions on reactive aggression via anger. In order to test whether the effect of the interventions on aggression at follow-up is moderated by violent intentions, callous-unemotional traits and negative urgency, a moderated regression analysis will be conducted using the PROCESS macro (Hayes, 2013). In the analysis, the intervention conditions (dummy coded) will be entered as the independent variable, violent intentions, callous-unemotional traits and negative urgency as the moderator variables, aggression at follow-up as the dependent variable, and aggression at baseline as covariates.