I have referenced the work of Jenny Hartley previously; she and Sarah Turvey are two UK academics who have done extensive research on reading groups and have worked with inmate book clubs. This Guardian UK article discusses their work with Wandsworth Jail inmates.
“It’s lovely to see people relax,” says [Niamh] Fahey, the librarian, who says it is her favourite part of the job. “The prison is full of tension. But there’s never any friction here. That’s quite special. It’s an oasis.”
The skills that emerge in reading groups, says Hartley, are respect for others’ opinions, learning to express oneself, and overcoming aggression. “Listening to each other’s opinions,” says Hartley, “is about learning you can disagree but remain friends. All sorts of arguments come out from a book or character. That’s what literature is for.”