John Harris: The consciousness of these people remains a closed door

To know whether or not someone is really 'there' involves more than evidence of consciousness

The fascinating work reported today in the New England Journal of Medicine from an Anglo-Belgian group raises a puzzling and deeply important question: how do you know when you are communicating with a real person when you cannot talk to them?

What happened in the experiments is that certain parts of the brains of people thought to have no consciousness at all were "activated" when they were asked to think about certain things, when they were asked to imagine playing tennis, for example. The same areas of the brain were activated when healthy control subjects were asked the same question.

The key question is: was the same "thing" going on in the healthy subjects and in those thought to be incapable of consciousness – in other words, was this brain activation actually brain activity?

This may sound like a rather sterile semantic distinction, but "activation" may be passive or a simple reflex, whereas "brain activity" implies conscious use of the brain by the individual whose brain it is; it implies deliberate action. Even, as in one of the cases, where there does seem to be communication, it is still difficult to have any idea what sort of consciousness it is that might be responding.

It is also important to note that even this activation of the brain occurred in a very small number of those brain-damaged individuals tested (only five out of 54). But even five people in every 54 who are still ghosts in their own bodily machine and who might be helped is a very significant number. If they are really still "in there" and trying to answer our questions and hoping to receive the help they need, then of course we should try to respond.

To know whether or not there is really someone in there involves more than evidence of consciousness or communication. We communicate with animals and they are conscious, but most of them are not persons whom it would be morally incumbent upon us to rescue at great cost if there is a chance that we can.

What's special about people is their capacity for what is sometimes called a "biographical life". Someone with a biographical life is aware of himself or herself, has hopes, fears, memories: he or she is someone with a past and a future of which they are aware, who can experience happiness and misery, and who wants to choose between them.

That's the sort of person we want to return to being if we suffer brain damage and the person that those who care about us want to welcome back.

If I was in a vegetative state I wouldn't want to come back without coming back to a biographical life. I would want those who were keeping my body going to know whether my brain was active or merely activated, whether I was living a life in there or whether my brain was simply responding to external stimuli. That is the question that still remains to be answered.

Professor John Harris is director of the Institute for Science, Ethics and Innovation at the University of Manchester