Not having access to adequate forms of mental stimulation and activities for normal socialization, however, can reach the standard of torture, before long. Ramp it up enough, and eventually you're inflicting irreversible brain damage.
Whether it's either cruel or unusual is a subjective question.
What I asked was whether it's ok for a prisoner's quality of life to be determined by the whims of the prison. I'm of the opinion that whatever the right quality of life is, it should be consistent across the board. If I commit a federal crime, the punishment shouldn't vary based on which prison I get sent to.
In other words, if you think it's perfectly reasonable for, say, a murderer to be placed in extended isolation (as an example), then that should be applied evenly to all murderers.
Surely we agree on that much? Or do you believe being a criminal means you should be subject to arbitrary punishments at the whims of your captors?
It's pretty cruel to allow a person's mind to decay due to lack of stimulus. Prisoners need something to do. Books and board games are cheap and keep people occupied.
"Not having access to entertainment is not cruel or unusual"
Do you mean by some legal definition, psychological, or personal opinion?
Personally, I don't see how spending most of your day in a cell without a book or game, for years, wouldn't result in severe psychological damage. Damage that might have consequences for others once you're eventually released.