Antonio Damasio

DESCARTES' ERROR

Emotion, reason, and the human brain

There's a tendency for writers on the mind/brain problem to concentrate on reasoning and the logical faculty and to regard the emotions as a rather regrettable complication, of no real importance to our understanding of how our minds work. And even if they do accord importance to emotion, they often seem to regard it as something separate from intellectual activity. (For understandable reasons this is particularly true of those who favour the view that the brain is more or less a computer.)

This is "Descartes' error", according to Damasio. He is a neurologist who has become convinced, by his observation of patients with brain damage, that reason alone is insufficient even for the efficient operation of the intellect. Damage to certain brain areas, notably the prefrontal cortex, can leave the patient apparently intellectually unimpaired but incapable of making complex decisions. Such a patient, for example, may understand the factors involved in conducting his business but may nevertheless keep reaching decisions that are manifestly disastrous.

The cold robotic decision-making that, for many science fiction writers, characterizes the mental processes of super-computers or Star trek's Mr Spock is really typical of brain-damaged individuals; it doesn't work well in the real world. In other words, we need our emotional biases in order for our complicated decision-making to work. The prefrontal areas of the brain are critical here.

The archetypal instance of the effects of prefrontal damage is Phineas Gage. In 1848, in New England, Gage suffered an injury in which a tamping rod he was using to compress a blasting charge was blown through his skull by an explosion. It destroyed much of the front part of his brain, but he survived and, at first, appeared to be largely unaffected. However, his personality was profoundly altered; from being a responsible foreman he became feckless and irresponsible, unable to hold down a job for any length of time.

Damasio describes this case at length and also discusses other broadly similar cases of which he has personal experience. He gives details of how his patients performed on mental tests and how their lives were affected. Like Gage, these patients were apparently more or less intact intellectually but their ability to function as complete human beings was subtly but profoundly impaired.

For example, one of these patients had a brain tumour successfully removed but his frontal lobes were inevitably damaged during the operation. Although his intelligence was unaffected, he could no longer carry on his professional work. He had to be prompted to go to work, and when he got there he might start on one task and persist with it even when it was time to change to something else, or he might spend the whole day pondering how to classify a paper he had just read. Thus he could manage isolated tasks well but couldn't integrate them into a wider frame of reference. He lost his job, became involved in unwise financial speculations, and ended up bankrupt. In spite of being confronted with the diastrous consequences of his decisions, he was unable to learn from them.

So what is wrong with patients like these? What is missing? The answer, according to Damasio, is emotional biasing. In people with normal brains, their decisions are "weighted" by emotions and this enables them to take decisions quickly according to how they feel. Patients with damaged prefrontal lobes, in contrast, are robot-like. He illustrates this vividly by means of an anecdote.

A patient with this kind of brain damage had driven to the hospital on icy roads; he recounted his experiences en route logically and dispassionately, describing how he had avoided accidents by calmly applying the rules for driving on ice, while others about him were panicking and skidding by slamming on the brakes. Yet when he had to decide between two dates for his next appointment, he spent half an hour listing the advantages and disadvantages for each of the proposed dates, until at last, in desperation, Damasio told him which date to come, whereupon the man thanked him, put away his diary, and left. This episode, Damasio says, illustrates the limitations of pure reason in making decisions.

Descartes' famous cogito—I think, therefore I am—is profoundly mistaken, according to Damasio. Thinking is a late evolutionary development. Long before there was thought, there was feeling; and we are still primarily feeling organisms. The same mistaken idea underlies the currently fashionable view that mind is a software program embodied in a brain. Those cognitive scientists who talk in this way are unconsciously falling into dualism--something they would no doubt fervently deny if it were suggested to them! There are important implications here for medicine, which Damasio touches on in a postscript.

Much of the book deals with the brain, but Damasio makes the important point that it is not only the brain that we need to focus on; feeling includes the body as a whole. He uses the metaphor of a landscape to describe this idea. The viscera (heart, lungs, gut) and the muscles are the components of this landscape, and a "feeling" is a momentary view of part of that landscape. These feelings are totally essential to the quality of being human. "Were it not for the possibility of sensing body states that are inherently ordained to be painful or pleasurable, there would be no suffering or bliss, no longing or mercy, no tragedy or glory in the human condition."

This is a book that should be high on the reading list of anyone who is interested in mind-brain questions or psychology and should also, I suggest, be read by doctors and members of other professions involved in dealing with patients; they will learn a lot from it.