SINCE the death of Kim Jong-il, images of weeping North Koreans have filled the western media. But is their grief real? Some have suggested that the hysterical displays of mourning were staged. Others have a shorter answer: brainwashing. But what does that mean?

The word ‘brainwashing’ was coined in the Korean war: it was CIA man Edward Hunter’s attempt to explain footage of captured US personnel supporting communism and denouncing the West. The soldiers had undergone a process of ‘thought-reform’ in Chinese prison camps.

For westerners raised to believe in strength of mind and individual free will, brainwashing was a nightmare. Zombies and demonic possession have staying power in our cultures for good reason: they represent the terror of mind control. And as possession was all about black magic, so brainwashing reeks of dark science. What else could explain those US soldiers’ behaviour but mind-altering technology? Except that, even in secretive North Korea, we can be pretty sure there is no such thing. So what, apart from propaganda, is it?

The thought-reform did not use new technology but old psychology, cleverly applied. Chinese culture was more aware of how groups can manipulate individuals. They used that social power on American prisoners and in their own societies. We see it now at work in North Korea. In this sense, brainwashing does exist. People can be made to believe things.

Brainwashing pushes to extremes persuasion techniques developed over centuries, using a highly coercive, controlled environment. A prison camp is ideal; an authoritarian dictatorship can come close. The intense social pressures make adopting — or appearing to adopt — new beliefs the easiest course of action.

The five basic techniques use isolation, control, uncertainty, repetition and emotions. They work because our brains are not static and self-sufficient, but constantly updating information.

First, move the person somewhere new. Isolation changes the brain’s inputs. Second, control the new environment, especially inputs that might trigger former beliefs. Surround the person with believers. Ban media and Internet, or govern what they show.

Use uncertainty. We humans hate it. Challenge old beliefs until they seem ridiculous. Chinese thought-reform used intensive criticism. People wrote their thoughts in diaries, which were subjected to group analysis: a hunt for signs of ideological deviance, which could be extremely hostile and psychologically devastating.

Use repetition. Brainwashing doesn’t happen fast; it takes time and effort. Chinese dissidents, sent for re-education far from home, could be interned for years. Finally, use strong emotions. Punish when former beliefs are mentioned; reward support for new ones.

Combined over years, these techniques are immensely powerful. Yet even North Korea’s control is far from total. The more the regime is seen as a source of uncertainty and hardship, rather than a protection, the likelier it is to crumble — and that collapse could be very rapid. Not all the tears are genuine.

But nor are they all fake. Kim Jong-il offered stability. However he abused his long-suffering people, the fear they must now be feeling is surely real.

— The Guardian, London