if it helps to calm them down and if it helps to make it easier to handle them, i think it can have a positive effect. since i'm no psychologist and since i don't know this guys and how it changed the situation in the prisons since they have videogames i can't really say if it works or not.
but i think you have to give them something so they don't get the worst depressions you can imagine in a prison which can convince those guys to make too much shit. as more avocation they have as better it could be for the situation for everyone in the prison and not only for the inmates.







