To deal with these problems, a multifaceted approach has been adopted by the department. The standard of physical security has been improved by erecting perimeter fences, installing security devices, and creating more supervisory posts. In addition, secondary security mechanisms such as a categorization system and anti-Triad gang units aimed at monitoring the behavior of potential trouble makers in prisons has been introduced. An effort is also being made to encourage prisoners to utilize their spare time by becoming more actively involved in self study and educational classes, and a psychological service which has helped to deal with the more difficult prisoners through assessment exercises and psychotherapy. Finally, a more comprehensive program of staff training has been instituted which tackles the subject of training at all levels. Existing programs are constantly under review and legislative provisions are examined regularly to ensure that the prison service is adapting to changing social conditions.