In the past I heard that people who live long‑term in a pure white‑light environment have their circadian rhythms and mental state distorted. The “loneliness punishment” of prohibiting any contact with others sounds milder, but it’s unclear what degree of effect it can achieve.
Today I heard Ko Wen‑je say that when detainees are under a no‑contact restriction, they must leave the cell, and everyone else must pause their actions, turn their backs to the wall and refuse contact. I immediately thought of the extreme punishment in The Country of Wheels where Higuchi Ririko forbids any contact with anyone, yet they can move around freely. Of course, in literary works the protagonists are naturally lively; Ko’s speech was also clear, but he can still communicate with his cellmate while in the cell. In the past, there were wild people who lived on a mountain for over a decade, who could speak but were easily alert and startled; however, wilderness survival adds extra pressures and animal threats.
If the punishment is simply a prohibition on any contact with others, perhaps the consequences aren’t especially severe. I have imagined that atomic beings might develop extreme thoughts due to lack of communication, but that process is slow and subtle, seemingly unlikely to cause mental or physiological injury.