The main goal of this randomized controlled trial is to investigate the effectiveness of VR-TRAC (Virtual Reality TRaining for Aggression Control) for reducing aggression in a prison-based population. The study-design is a single-blind randomized controlled trial, comparing VR-TRAC to waiting-list control condition (WL). 128 male detainees with aggression regulation problems in the last month (measured with the Aggression Questionnaire [AQ]) and a minimum age of 18 years, recruited from the Penitentiary Institution (P.I.) Vught, the Netherlands will participate in this study. They are randomly allocated to VR-TRAC or control condition WL. The treatment group fills in questionnaires, participates in role-plays and follows the VR-TRAC. The control group filles in the same questionnaires as the treatment group and also participates in the role-plays, but does not participate in the VR-TRAC. Participants receive Care As Usual (CAU) when necessary.

To measure the effect of VR-TRAC on aggression, three different types of measurements are used: staff observation, self-report and performance-based. Self-report questionnaires will be scored on three different moments during the study: before the treatment starts, at the end of the treatment, and two- months after the treatment ended. Throughout the sessions, participants are also asked to answer questions to evaluate the sessions. Lastly, to measure the effectiveness of the skills trained in the VR-TRAC, performance-based assessments (role-play tests and vignettes) will be conducted before and after the treatment period.

In an earlier pilot study the Virtual Reality Aggression Prevention Training (VRAPT), developed by Klein Tuente, was explored and refined for a prison-based population. Changes were made and the training was adjusted to Virtual Reality Training Aggression Control (VR-TRAC). In this study the effectiveness of VR-TRAC will be explored.

The main goal of this randomized controlled trial is to investigate the effectiveness of VR-TRAC (Virtual Reality TRaining for Aggression Control) for reducing aggression in a prison-based population. The study-design is a single-blind randomized controlled trial, comparing VR-TRAC to waiting-list control condition (WL). 128 male detainees with aggression regulation problems in the last month (measured with the Aggression Questionnaire [AQ]) and a minimum age of 18 years, recruited from the Penitentiary Institution (P.I.) Vught, the Netherlands will participate in this study. They are randomly allocated to VR-TRAC or control condition WL. The treatment group fills in questionnaires, participates in role-plays and follows the VR-TRAC. The control group filles in the same questionnaires as the treatment group and also participates in the role-plays, but does not participate in the VR-TRAC. Participants receive Care As Usual (CAU) when necessary. CAU in prison consists of treatment with the main focus to stabilize a disrupted psychological state (such as pharmacological treatment, supportive contact or a transfer to a Penitentiary Psychiatric Centre where necessary interventions are applied to stabilize the disorder).

The training consists of 16 twice-weekly sessions, with a duration of 60 minutes each. The first four sessions focus on the early stages of information processing (what is happening and what does it mean). Session five through eight focus on the late information processing stages (what goals am I trying to achieve, what options do I have to react, what am I going to do, and what is the reaction or behavior). Session 10 through 15 combines the early and late stages, as all newly learned behavior will be incorporated in the interactive scenarios. To train the aforementioned stages, different aggressive-inducing situations are practiced in VR.

To measure the effect of VR-TRAC on aggression, three different types of measurements are used: staff observation, self-report and performance-based. Firstly, through staff-observation, using weekly scores of the Observation Scale for Aggressive Behaviour (OSAB) throughout the study period. Secondly, individual changes are measured through self-report measurements. The questionnaires will be scored on three different moments during the study: before the treatment starts, at the end of the treatment, and two- months after the treatment ended.

Four questionnaires will be used to measure different types of aggression, namely the Aggression Questionnaire (AQ) (which will also be used as a screening measurement), Difficulties in Emotion Regulation (DERS), the Novaco Anger Scale and Provocation Inventory (NAS-PI), and the Reactive-Proactive Questionnaire (RPQ). To measure impulsiveness the Barratt Impulsiveness Scale (BIS-11) will be used. One questionnaire, the Short Anger Measure (SAM), will be used to measure feelings of anger in the last week. It consists of 12 short items measuring feelings of anger. The questionnaire will be scored weekly and starts four weeks before the treatment starts and will end four weeks after the last treatment.

Participants are also asked to answer some questions to evaluate the session through the SRS (Session Rating Scale).

Two additional self-report questionnaires will be conducted, one on childhood trauma with the Adverse Childhood Experiences (ACE) and one on substance abuse with the Addiction for Triage & Evaluation (MATE), Lastly, to measure the effectiveness of the skills trained in the VR-TRAC, performance-based assessments (role-play tests and vignettes) will be conducted before and after the treatment period.

Inclusion Criteria:

• Detainees who are imprisoned in P.I. Vught, The Netherlands, for at least 20 weeks.
• Detainees with aggression regulation problems in the last month, as measured with the AQ (a minimum score of 70).
• Minimum age of 18 years old.

Exclusion Criteria:

• SCIL score of 14 or lower. (SCIL: a screener for IQ and is scored for every detainee as part of the reintegration plan inside detention).
• Acute suicidal behavior or current psychotic episode.
• Insufficient command and understanding of the Dutch language.
• Photosensitive epileptic seizure in the past year.
• An estimated stay of 5 months or shorter