The authors of kubark working for the CIA were based on scientific studies making it a kind of synthesis of knowledge on this subject in 1963.
They present methods such as "sensory deprivation" also called "total isolation", the method of confusion generally applied method of regression. These seemingly innocuous methods or "relaxing" for the victims actually have devastating effects on their personality, generally leading to suicide. The definition of sensory deprivation on wikipedia actually a good summary.
The book "confession" that shows slow decline bringing the individual to a state of exhaustion and psychological suffering, and suicide.
Since 1978, the European Court of Human Rights continues for acts of torture users of methods of psychological disorientation and sensory deprivation as in the Irish case against the UK.
The International Committee of the Red Cross has also published a paper on the psychological torture that arrives at the same conclusion and where kubark cited therein: [...]
Today, these methods are used in companies. We found on the internet a watered down version to HR calling "management by terror".