Many problems can’t be solved by traditional systems of intelligence. Sometimes ‘sleeping on it’ can be more fruitful. You never know what might fall out of the tree, writes Anthony Storr

In the Western world, intelligence is often equated with the kind of directed, logical thinking which perceives the essence of a problem, reviews possible answers, rejects those which are obviously wrong, and then reaches the correct solution. Solving a difficult crossword puzzle is one example of this type of mental functioning; and the faster the puzzle is completed, the more likely we are to regard the solver as “bright” or “smart” or “clever”.

Guy Claxton, visiting professor of psychology and education at the University of Bristol, acknowledges the importance of this variety of thinking, which he calls “d-mode”, but his main concern is with those mysterious, subterranean mental processes which cannot be voluntarily controlled. These may eventually present the subject with a creative solution which appears to “come to” him or her from some source beyond the ego. Such processes go along at their own pace, which is often very slow, so that it may be months or years before the solution manifests itself. Hence Claxton’s title, contrasting hare and tortoise.

Anyone who has read or written about creativity knows this to be true. Graham Wallas described the creative process in terms of Preparation, Incubation, Illumination, and Verification in his book The Art of Thought as long ago as 1926, and Rosamond Harding’s invaluable An Anatomy of Inspiration was published in 1940. Hadamard’s book, The Psychology of Invention in the Mathematical Field, appeared in 1945. Many people know the stories of Poincare and Gauss fruitlessly pondering over mathematical problems for months, and then finding that the solution suddenly occurred to them when they were thinking about something else.

Everyone from Koestler to Claxton and myself acknowledges the irrationality and unpredictability of creative insight and quotes what has now become a cliche: Kekule’s discovery of the ring structure of organic molecules, which originated from his vision, while dozing, of chains of atoms coiling themselves into snakes eating their own tails. It has long been accepted that much of our information processing proceeds unconsciously. So what has Claxton got to tell us that is new?

Claxton, a well-read experimental psychologist, backs up anecdotal studies of creativity with up-to-date information about the latest research into brain function. The result is a fascinating book which told me many things I ought to know but didn’t. I am hugely grateful to him.

At last, we are beginning to perceive bridges between “mind” and “brain”.Admittedly, these are rickety, insecure links, more like rope bridges over Himalayan torrents than the solid structure spanning the Golden Gate. New discoveries may reveal our ignorance and plunge us into the abyss; but research into unconscious perception makes it clear that conscious deliberation is only a small part of mental functioning. In fact, this book resuscitates the importance of the “unconscious” in a way which is closer to Jung than it is to Freud.

The picture I gain from it is of a cerebral activity quite independent of the will that is ceaselessly striving to make sense of the world and of one’s own subjective experience by creating new schemata or neuron A1 networks, which are the anatomical substrate of schemata.

In fact, the d-mode of thought, though indispensable on occasions, can actually impede understanding because it depends on tunnel vision. The searchlight of consciousness brightly illuminates a tiny area of the field,but takes no notice of the shadowy remainder. There is experimental evidence which shows that certain types of competence can actually be diminished if subjects try to articulate verbally the rules which govern what they do.

Some of the most intelligent people in the world are not particularly creative. Philosophers sometimes have a marvellous critical capacity which instantly detects flaws in any argument, but remain incapable of producing a novel or original conceptual scheme because they rely on d-mode functioning to the exclusion of intuition. (This used to be known as being “too clever by half”.) Research programmes that demand d-mode functioning be-cause they are sharply focused and oriented to-ward obtaining quick re-sults are less likely to produce original discoveries than programmes which allow for day-dreaming and serendipity. As Howard Gardner has shown in his book, Frames of Mind (Fontana), there are varieties of intelligence which do not employ d-mode functioning and which cannot be measured by conventional IQ tests.

There is now experimental evidence which demonstrates the value of incubation or “sleeping on it” when faced with problems. Einstein once defined thinking as “playing with concepts”. In answer to a question as to how he came to make his discoveries, Newton said: “I keep the subject constantly before me, and wait till the first dawnings open slowly by little and little into the full and clear light.” Kekule said to his students: “Let us learn to dream, gentlemen. ” He might have added, “Let us learn to meditate and to play.”

Anthony Storr is the author of Feet of Clay: a Study of Gurus (HarperCollins)