Omar Khadr was not tortured. He may have been hooded, shoved, shackled to a wall, humiliated, threatened with guard dogs, told he was going to be sent to the Middle East for torture, forced into painful stress positions, and deprived of sleep. He may have been warned that another prisoner who had refused to co-operate had been gang-raped to death. But he wasn't tortured. We've heard variations on this claim all this week, as Khadr's hearing in Guantanamo staggers to its wretched conclusion. American officials did nothing wrong, many say. Khadr wasn't tortured. Is that true? There are two ways of tackling the question. One is legal analysis. International and national law is emphatic in forbidding torture, but it does not provide a precise, technique-by-technique definition of what is and what is not torture (or "ill treatment," a secondary category of acts that do not rise to the level of torture but are nonetheless forbidden). Agreements and precedents help clarify things. But still, there is plenty of room for argument. But before we get to the law, we have to investigate the reality and answer the most basic question: What is torture? Seven years ago, I spent six months answering that question. I travelled to Egypt, Turkey, and Uzbekistan. I spoke with physicians and psychologists. I spoke with police officers and activists struggling to stamp out endemic torture. I spoke with victims who had suffered every imaginable abuse of the body and spirit. It was a profoundly disturbing experience. At the end of it, I knew what is known to everyone who has suffered, inflicted, or treated torture. Torture may sometimes involve the deliberate infliction of severe physical pain, but that is not its core. Physical pain is merely one technique available to the torturer. At its core, torture is a psychological assault. "The basic goal of torture is to destroy the person's worldview, how they see the world, and their place in the world," I was told by Dr. Richard Mollica, a Harvard psychiatrist and a pioneer in the study of the trauma of torture. Torture is an attempt to smash the self, to "break" the person, said Judith Pilowsky, a Toronto psychologist who has treated hundreds of torture victims from around the world. "It's the same metaphor in every language. I'm broken, I'm destroyed, I'm nobody." In reality, there is no separate, lesser category of "psychological torture." All torture is "psychological torture" because all torture targets the mind. This is the essential insight needed to judge whether what was done to Khadr, or anyone else, constitutes torture. Consider threats. Reasonable people will agree that mauling a helpless prisoner with guard dogs is torture. But is it torture to threaten to do so? Many people would say no. What's a threat? Mere words. This thinking is deeply misguided. After assembling a group of volunteers in the Netherlands, researchers told half the participants they would receive 20 strong electric shocks. The other half were told they would get 17 mild electric shocks, plus three randomly interspersed electric shocks. All the volunteers were monitored for the standard physiological responses to fear, including elevated heart and respiration rates and sweaty palms. The researchers found that those who received 20 strong electric shocks experienced much less fear than the others. Why? Because the shocks they received were not only stronger, they were predictable. Those who received the mostly mild shocks couldn't be sure if any one shock would be mild or strong -- and so they experienced more fear even though they suffered less physical pain. Other research has come to similar conclusions. The threat of something bad can not only be as psychologically devastating as the bad thing itself, it can be worse. This is why threats are a standard part of the repertoire wherever torture is used, including in countries where officials can inflict physical pain with impunity: the threat of pain can break a prisoner more effectively than pain itself. Think I'm a crazy liberal bleeding-heart? Read this: "The threat of coercion usually weakens or destroys resistance more effectively than coercion itself." And this: "The threat to inflict pain, for example, can trigger fears more damaging than the immediate sensation of pain .... Sustained long enough, a strong feeling of anything vague or unknown induces regression, whereas the materialization of the fear, the infliction of some sort of punishment, is likely to come as a relief." These statements from a leaked Central Intelligence Agency manual on interrogation. In the annual U.S. State Department reports on human rights on other countries, threats are often described as a form of torture. Because they are. After his capture, the gravely wounded 15-year-old Omar Khadr was in an environment of radical uncertainty. It was two years before he was even allowed to speak to a lawyer. Now, imagine being threatened with rape, torture, death, or mauling by vicious dogs in that environment. Then go back and re-read what the CIA wrote about the power of threats. Was Omar Khadr tortured? Yes. He was tortured.