So  if you think about it a therapeutic group could certainly use suggestive therapy like hypnosis and my guess is that most successful groups like Alcoholics Anonymous or groups of people who wanna stop smoking or do slimming and things like that succeed for that reason, cos every member of the group reinforces every other member with a kind of group super ego and says look, you mustn't smoke, you mustn't drink, you mustn't put on weight and it, it reinforces every individual's erm  super ego by means of identification with the shared value of the group and  similarly reduces feelings of shame and guilt if the individual fails the group, cos next week when they come back they say oh dear, I've put on five pounds, erm that they're gonna feel bad about it because it offends against the ideal of the of the group if it's Weight Watchers or something.