The experimenters took young adult volunteers and subjected an area of their skin to increasing levels of heat until it became painful, all the while scanning their brains. In another experiment they compared physical pain with social pain: the experimental subjects had recently had a broken relationship and their brain scans when being showed pictures of their late sexual partners were compared with those when subjected to painful warmth on their skins. They also studied the effect of painful stimuli when the patient had been administered a powerful analgesic.

The subjective feeling of physical pain correlated with activity in certain areas of the brain with considerable consistency. This, the authors stated, raises the hope that brain scans might be able to tell doctors when patients who are unable to express themselves for one reason or another are suffering pain, and thus treat their suffering.

The study has its limitations, however. It is an elementary logical error to say that because part x of a person’s brain lights up on a scan when he is suffering pain he must be suffering pain when part x of his brain lights up. This might be so, but it has to be shown to be so. In fact, it is prima facie rather unlikely, given the immense complexity of the brain and its vast numbers of interconnections. Furthermore, one must remember that the experiments were performed in a very simple situation, quite unlike the real-life situations that doctors actually face. Still, one cannot but admire the accumulated human ingenuity that made these experiments possible.