Can the psychological conditioning of soldiers explain the massacre of 16 civilians by a lone US soldier in Afghanistan? Photo: Tanya Lake

IN 1947, the official US historian of the Second World War, Brigadier General S.L.A. Marshall, published Men Against Fire. Marshall's astonishing contention, debated vigorously ever since, was that about 75 per cent of WWII troops were unable to fire their weapons on the enemy. Guns were discharged, but they would be deliberately aimed over the heads of the enemy. The majority of soldiers couldn't kill. And, in the midst of combat, they became de facto conscientious objectors.

Historians have questioned the way Marshall gathered his evidence. But few have denied that most people find it extremely difficult to kill another human being. It is one thing to sit in a bunker in Nevada and anonymously direct a drone into attack with a joystick. It is quite another to track a fellow human being in the sights of your rifle. Natural human empathy generates huge psychological resistance to up-close-and-personal killing. We have an inbuilt safety catch. So how is it that a US soldier can walk into an Afghan village in the middle of the night and calmly shoot 16 civilians dead? Nine of them were children.

One explanation is the use of psychological conditioning that the US army uses on its troops to prepare them to kill easily. Both the US and British armies took Marshall's book extremely seriously. A soldier who cannot kill is about as much use as an accountant who cannot count. So the military began to think harder about the ways in which they might override the natural human aversion to killing, turning to the developing science of cognitive behavioural psychology for advice. And it worked. When Marshall was sent back to the Korean War in 1953, he found that the training techniques developed by psychologists had begun to work. Now 55 per cent were able to fire on the enemy. By Vietnam, it was up to 90 per cent.

Since humans first went to war, soldiers have looked for ways to avoid the full reality of their work by the creation of emotional distance. The enemy is demeaned as less than human. And since the Second World War, two psychological categories in particular have been folded into the design of military training: desensitisation and conditioning. The use of violent films and video games make violence seem ordinary. The culture of barrack-room banter is aggressive and bloodthirsty.

As well as this, training is deliberately arranged so as to replicate a killing environment. No longer do soldiers shoot at circular targets; they shoot at dummies made to look as much like people as possible. Throughout training, killing is made all too familiar, the act of killing continually rehearsed. The process of becoming a modern soldier begins with behaviour modification. Following this latest massacre in Kandahar there will be much talk of a lone gunman going off the rails. But the truth is more disturbing. One cannot set in place the conditions for easy killing, removing the inbuilt human safety catch, and then simply blame an individual soldier who flips out.

GUARDIAN