1. Introduction

Creativity is one of the cognitive functions which contributes to sociobiological adaptation. It can be defined as the ability that allows the production of new or unusual associations among known ideas or concepts. This definition highlights those aspects most relevant to the creative process the elaboration of information (knowledge, what it is already known) through contrast and comparison of data; and the production of associations which are original, i.e. not already part of acquired knowledge (memory). Other definitions of creativity are quite possible. Frank Barron, one of the most authoritative researchers in this field offers an articulate description of creativity. Creativity is first conceived in terms of the characteristics of the creative product and the social acknowledgement it obtains creations in fact are products which appear new and are considered valuable by consensus. Secondly the creative product can be considered in its own context the difficulty of the problem resolved or identified, the elegance of the solution proposed, the impact of the product itself. Thirdly creativity can be conceived on the basis of the abilities that favour it, i.e. as skill or aptitude (Barron and Harrington, 1981). Many studies recognize creativity as a cognitive ability separate from other mental functions and particularly independent from the complex of abilities grouped under the word 'intelligence' (McKinnon, 1962; Dellas and Gaier, 1970). Although 'intelligence' ¾ the ability to deal with or process a large amount of data ¾ favours the development of creative potential, it is not synonymous with creativity. Higher scores in tests which measure intelligence factors do not guarantee expression of a creative talent. The two most complete studies on this subject, that of Terman, conducted on a group of talented children who were followed right through their lives, and the study of McKinnon on architects indicated as cleverer than the mean by their colleagues, showed that intelligence gifted individuals attain significantly higher levels of personal and social achievement than the mean of the general population with better physical and mental health (although with higher suicide rates), but they do not show greater creative abilities than others (see McKinnon, 1962; Richards, 1981).

2. The Psychoanalytic Approach

Psychoanalists were among the first to indicate the importance of subconscious elements in the production of a creative result (Kris, 1952). Sigmund Freud (1907) thought that unconscious conflicts concerning powerful biological drives, such as sexual impulses and even more archaic nutritional drives, provided motivation for creative effort in terms of the energy that must be harnessed for productive enterprise, thus diverting it from less controllable enterprise which could potentially generate anguish. Otto Rank noted that, in the artistic field at least, these same unconscious conflicts, disguised or revived, could offer matter other than energy, to the creative action, allowing the expression of socially condemned drives, such as those linked to envy, hate and jealousy, in a sublimated form. Melanie Klein (1948 see particularly 'A contribution to the psychogenesis of Manic-Depressive states'), and Donal Winnicott (1971) after her, indicated the importance of depressive feelings in the elaboration process of mourning that follows the recognition of the separateness of the Loved Object, a process which, according to psychoanalysts of the British School, constitutes the basis for the development of the ability to symbolize. If a symbol takes the place of something that is not there it can only come into being when the symbolised object is conceived as distant and separate from the Self and every separation contains the seeds of depressive grief <<thinking is thinking about what is not there>>. The desire to recover total appeasement close to the Loved Object imposes the need to reconstruct and re-integrate the object which separation has forced one to think of as broken. The control over this complex affective drive, which is provoked by elementary biological impulses and by the emotions linked to them, is sustained by the same forces that give rise to language as an instrument of communication. Language, like the arts, is based on a recourse to symbols in Greek language the word 'symbolon' derives from 'symballein', a verb meaning 'to reunite'. The etymology of the Greek word 'symbolon' is anecdotally described in the following story in ancient times, when two friends separated they broke a tablet which had a scroll carved into it. When they joined together again, they reunited (= 'symballein') the fragments of the tablet and so restored the broken scroll. The broken tablet (with the divided scroll) possessed by each friend was called a 'symbolon'. The creative character of the symbolon consists in its ability to complete the object, incorporating even the absent part a symbol, like an artistic work, invokes a uniqueness that can only be maintained by remembrance. At the origin of the symbol is a destructive act the breaking of the tablet bearing the carved scroll. This links the process of reintegration, offered by the act of symbolisation, to the process of restoration of the Loved Object by emotional forces moved in turn by depressive anguish.

The role of depressive feelings and, more generally, the role of perturbed psychic states in the development of creativity is indicated by studies that explore the relationship between mental disorders and creativity. In fact one characteristic seemingly linked to creative talent is the propensity to develop psychiatric disorders, the prevalence of which among creative individuals appears significantly higher than in the general population.

3. Creativity and Mental Illness

The Italian psychiatrist and criminologist Cesare Lombroso has over the past century been the most consistent supporter of the hypothesis which asserts that there is a close link between mental ilness and creative achievement (see Lombroso, 1891). He was not the first, however more than two millenia earlier, in the fragment known as 'Problemata XXX', Aristotle, or a disciple of his, raised the question as to why the vast majority of the eminent people are afflicted by 'melancholy', i. e. suffer from a mental disorder. The text, now accepted as part of the Aristotelian canon, is surprising in its modernity and accurately describes those characteristics peculiar to one of the most diffuse mental disorders, namely manic-depressive psychosis. The author of the Problemata XXX indicates many behavioural characteristics as attributes of the more eminent people of his time (attributes such as mood, instability, proneness to depressive withdrawal, impulsiveness, tendency to alcohol and drug abuse, high risk of suicide) all of which are peculiar to patients suffering from manic-depressive illnesses. In the Problemata XXX there are also illustrative stories taken from myth and literature, with a gallery of examples mixing both excellence and weirdness, often with a tragic outcome. Indeed, the image of madness as a result of genius has been repeatedly expressed in the history of the Western world, being codified during the Renaissance in the figure of the melancholic genius afflicted by Saturnian acedia, and resurfacing during Romanticism in the figure of the Deracine artist (see Starobinski, 1960; Klibansky et al., 1983). Cesare Lombroso was among the first to apply a less anecdotal method to the investigation of the relationship between the creative gift and the risk of a mental illness, offering an answer that is nevertheless the positivistic version of the romantic myth. Most studies performed in the positivistic era in order to either confirm, or refute, Lombroso's hypothesis rest on biographical evidence (see Richards, 1981). This raises the suspicion that these studies claiming a higher prevalence of psychopathologies among creative or eminent people, were biased by overexposure. For individuals in the public eye such as artists more information is available about their private lives this could determine an apparently higher prevalence of disorders that tend, as a result of negative stigma, to be hidden whenever possible. In addition, some temperamental traits widespread among creative people, like eccentricity, uneasiness, propensity to excess and experimentation, could be a reflection not only of an underlying mental disorder, but also, and above all, of the tolerance by society of the behaviour of high achieving individuals. In some way this behaviour will be a secondary product of the achievement, rewarded since it permits the expression of dissenting demands which the majority of people are not able to express and which are not directly linked to the creative utterance. Despite these reservations, even later studies, performed using methods applying specific nosographic categories and direct confrontation with the candidate through interviews and inventories, yielded similar results, with a higher prevalence of mental disorders among gifted people than among the general population (see Richards, 1981; Goodwin and Jamison, 1990, ch. 14).

The two principal studies performed in the era preceding the systematic ordering of the more recent classifications (DSM III, and now IV, and ICD 9, and now 10), show among both artists and scientists a prevalence of severe mental disorders significantly higher than among the general population, with a strong familial association between creativity, psychopathology, and higher suicide rates. In a study performed in Germany from 1927 to 1943 on 5000 individuals, Adele Juda, at that time researcher at the Munich Institute of Psychiatry, evaluated frequency and distribution of psychiatric disorders in a well selected sample of eminent artists, scientists and their relatives. The study shows a significantly higher prevalence of mental illnesses among eminent people and their families compared to the general population. Among artists, disorders of the schizophrenic spectrum and psychopathies were most common. Among scientists, on the other hand, disorders of the cyclotimic type, in particular manic-depressive psychoses, were more frequent. In both groups there was a high suicide rate and a strong familial heredity for the transmission of the psychopathological trait and of creative talent (see Juda, 1949). Some decades later, J.L. Karlsson, in a study of Iceland, reported a clear familial association between the diagnosis of psychosis, taken from hospital registers, and eminence in artistic or scientific fields, based on citations in Who's Who. A clearly recognisable creative talent was present in the relatives of schizophrenic patients twice as often as in the general population; and in the relatives of manic-depressive patients six times as often as in the general population. Karlsson, in his conclusion, suggests a familial link between creativity and psychoses, sustained by a common genetic basis (see Karlsson, 1978).

In both studie,s there is a clear association between the creative gift and the risk of schizophrenia, although mediated by a familial link this is surprising since in the concept itself of schizophrenia as illness there is implied a criterion of impairment. Schizophrenia, in fact, is a severe mental illness. It is a psychosis, i. e. a mental disorder which implies a severe distortion of reality testing. The clinical symptomatology can be traced back to the ex novo appearence of distortions in perception, such as illusions and hallucinations, and of thought disorders leading to delusions, and includes many different behavioural patterns, predominantly disorganized and inappropriate behaviour and speech, loss of will and drive, and a generalized lessening of the ability to express emotions. Positive symptoms, involving excess or distortion of normal functions, tend to fluctuate over time, whereas negative symptoms, involving loss or diminution of normal functions, seem to be more stable and less responsive to treatment. Studies performed with neuroimaging techniques indicate that brain abnormalities (i.e. signs of cerebral atrophy) can be the basis of schizophrenia, but the extent of such abnormalities depends on the characteristics of the control groups. The final step in the pathogenesis of schizophrenia appears to be a distortion of the systems involved in modulation or integration of information processing. A key role for dopaminergic pathways is suggested by the therapeutic efficacy of dopamine blocker agents, but, as the development of new 'atypical' neuroleptics with greater effects on serotonin indicate, many other neurotransmitters could be implicated in the defects in information processing.

The fact that such severe illness could in some way favour the expression of creative abilities, particularly in the artistic field, has raised enormous interest and provoked myriad studies. These studies were summarized in the Sixties by the Italian Silvano Arieti, an eminent researcher in the field of psychoses who for many years lived in the United States. In his book 'Creativity, the magic synthesis', Arieti elaborates his hypothesis that the thought processes typical of schizophrenic patients can favour the development of unusual mental associations which can, in turn, be inspiring to the creatively gifted individual, above all in the artistic field (see Arieti, 1976). Arieti supports his hypothesis in many ways, indicating the extraordinary talent of schizophrenic patients in coining new words, and giving many examples of the artistic production of patients confined in Asylums in the first half of this century. The works of these artists are often very odd and disquieting, but generally they do not possess the requisite of being 'socially enjoyable', essential if a product is to be judged creative. Interest in the artistic production of mentally ill patients lasted until the Sixties, when the introduction of more selective diagnostic categories lessened enthusiasm for the creativity enhancing virtues of schizophrenia. With the increase in the number of cases identified awareness was also raised that it was disorders with an affective (mood) component - those characterized by melancholy (i.e., severe depression) - that were more closely associated with creative achievement than disorders like schizophrenia, just as the author of the Problemata XXX asserted.

4. Melancholy and Creativity

Manic-depression or, as they are now called, 'bipolar' disorders are characterized by the alternation of depressive episodes (with melancholia, insomnia, loss of appetite, anxiety and restlessness) with other episodes with an opposite euphoric mood, excitement, higher energy and tirelessness, overconfidence, impulsiveness and imprudence (see Goodwin and Jamison, 1990). In the periods between two episodes those who are suffering from the disorder have a highly adaptive life style, sometime with very high level of functioning, thanks to the tenacity, tirelessness and social ease that are typical of these individuals. During an episode of illness, however, the social and occupational functioning of the afflicted individual is impaired, sometimes with irreparable consequences. As a whole the lives of bipolars are troubled, with a high risk of death by suicide one patient in ten dies by suicide, and the frequency of self-inflicted injuries is even higher (1 in 5 cases, according to studies). Nevertheless these individuals appear to have a unique gift for creative activity, and show a specific talent in the arts, sciences, philosophical speculation, and political and military leadership. The following all suffered from bipolar disorders in their lives the scientists Boltzmann and Babbage, the father of modern computer science; the composers Rossini and Tchaikovsky, who committed suicide drinking a cup of water contaminated with vibrio colerae; the statesmen Churchill and Lincoln; the painters van Gogh and Pollock; the philosophers Wittgenstein and Kierkegaard; the writers Pavese and Hemingway, both of whom died by suicide. Poets and writers seem to be particularly prone to developing mental problems, generally of a depressive type; it has even been asserted that one cannot write with success without being 'exposed to the Dark Sun of Melancholy'.

Nancy C. Andreasen, an eminent American psychiatrist who studied literature before devoting herself to medicine, performed an extensive study with her co-workers in the mid Seventies on the qualities which characterized the styles of thought of a group of writers who were participating in the annual Writer's Workshop of Iowa University, and, using the criteria of DSM-III, found a high prevalence among them of mood disorders of a bipolar type (see Andreasen and Glick, 1988). The style of thought of the writers investigated in addition showed more resemblances with the over-inclusive and imaginative style of thought of manic patients, than with that of schizophrenic patients examined in the same study. A clear prevalence of psychopathologies from the affective spectrum among creatively talented people was later reported by K.J. Jamison in a study dedicated to twentieth century English poets; by JJ Schildkraut and co-workers among American Abstract Expressionist Painters; and by AM Ludwig among 30 American female writers (see Jamison, 1989; Schildkraut et al, 1994; Ludwig, 1994).

Kay Jamison, in a study covering three centuries limited to writers and poets, found high rates of mood disorders, in most cases of a bipolar type (see Jamison, 1993). In the Jamison study, suicide and alcoholism rates were also very high as was the familial transmission of both psychopathological risk and creativity. Kay Jamison reports many examples in his study, among the more representative is one which concerns the poet George Gordon, known as Lord Byron, whose familial history was as replete with suicides and bizarre incidents no less clamorous than that which accompanied his own adventurous and unfortunate life.

The ability of bipolar patients and their relatives to express themselves successfully is not limited to the artistic field, however, and in fact achievement and ability seem to be attributes of the families of bipolar who appear time and again as motive powers for the advancement of mankind. Ruth Richards, who extensively studied this aspect of the relationship between mood disorders and creativity, found among bipolar patients and their relatives a high propensity to the development and expression of creative potential in every field, even those not mutually linked (see Richards et al., 1988). These abilities were evident mainly among individuals with slight or sub-clinical forms of the disorder. The healthy carriers of the genetic burden of manic-depressive psychosis seem in some way to draw an advantage from exactly the vulnerability they transmit.

5. The Gift of Saturn

One can only speculate as to the characteristics that confer such an advantage. In fact there are several aspects characteristic of manic-depressive psychosis which can offer a basis for these adaptive advantages. During euphoric phases cyclothymic individuals exhibit greater energy which can favour their involvement in productive activities and their ability to put up with fatigue. In addition, increased fluency of mental associations, which in mania is expressed in the dramatic experience of 'flight of ideas', allows a greater processing of information and a greater articulation of ideas, favouring original or unusual associations. This is often accompanied by improvements in both memory and concentration, which render even more productive the heightened imaginative potential of these individuals.

People with a bipolar mood disorder tend to be more emotionally reactive, which gives them greater sensitivity and acuteness. A lack of inhibitions permits them unrestrained and unconventional expression, less limited by accepted norms and customs. This makes them more open to experimentation and risk-taking behaviour, and, as a consequence, more assertive and resourceful than the mean. Sensitivity, lack of inhibition and hyper-activity make these subjects warmer in social intercourse and more friendly both aptitudes represent a clear advantage at work, particularly when competition is great. Even the depressive phases can favour abilities contributing to achievement introspection and reasoning are favoured during depressive withdrawn phases. Depressive episodes, in addition, give access to 'inner dimensions' of life, allowing considerations of themes linked to guilt, sorrow and death. The elaboration of these feelings can offer subject matter for creative expression in many fields, but particularly in the arts, as demonstrated by the high prevalence of depressive disorders among poets and writers. In effect, the experience of pain associated with a depressive episode can permit a better understanding of the human condition, allowing the transformation of this wider awareness in to a complete work. The extreme and sometimes very unusual experiences associated with more severe forms of the disorder can also offer access to uncharted existential dimensions, broadening the intellectual horizon of the subjects.

The creative process per se generates a sense of euphoria. This euphoric disinhibition could be sought in a active way by individuals such as bipolar patients who attribute a very great importance to sensations of excitement, often abusing drugs in a attempt to reproduce the euphoric mood. The reinforcing property of euphoria can direct these individuals towards risk-taking activities, increasing their chances of failure, but assuring greater glory when they attain their goal.

Other disorders show important links with creative abilities and achievement. Anorexia Nervosa, for example, is a disorder that is often associated with high performance in many fields people suffering from this disorder tend to show remarkable tenacity and determination.

6. Extra-Logical Aspects of the Creative Process

The aspects described above indicate extra-logical characteristics which could somehow be formalized. It is unlikely than an Artificial Intelligence program would develop habits reminiscent of alcoholism, but a program could develop social aptitudes in seeking to establish contacts with information sources (data banks) by itself, rather than waiting to be questioned about a particular subject. Software already exists which 'converses' with its users (e.g., Weizenbaum's 'Eliza' program, and its variants). Although these programs could not pass a rigorous Turing Test, they are certainly able to establish friendly relationships which can stimulate information exchange and reduce performance anxiety (at having to resolve a problem). Studies have also given evidence for other aspects of the relationship between mental disorders and creativity that could be useful to the 'planning' of creativity. The study of the style of thought of schizophrenic patients shows an interesting connection between some characteristics of schizophrenia and others that can be observed in creative people. Creative individuals often score higher on psychopathological scales in standardized tests, like the Minnesota Multiphasic Personality Inventory (MMPI), particularly on scales which measure traits of psychoticism. Often creative individuals report odd sensory and perceptual experiences, feelings of restlessness and inclination towards impulsive outbursts in association with rejection of common social values and highly unusual experiences, just like schizophrenic patients (see Cattell and Drevdahl, 1956; Dykes and McGhie, 1976; Woody and Claridge, 1977).

Highly creative normals also tend to show over-inclusive or 'allusive' thinking and, as pointed out by Albert Rothenberg (1971), show the capacity to conceive and utilize two or more opposite or contradictory ideas or concepts simultaneously, without being disturbed by this simultaneity of opposition, as happens to schizophrenics. It seems that creative individuals, like schizophrenics, are capable of a widening of selective attention, which renders them more aware of and receptive to experience, with a more intensive sampling of environmental stimuli (see Hansenfus and Magaro, 1976). In fact ideational fluency and a preference for complex and asymmetrical designs (two of the main factors contributing to creativity) could derive from higher levels of arousal and from faster stimulation of discrete cerebral areas. Schizophrenics tend to make unusual associations, resulting in ove-rinclusive thinking, with many irrelevant elements included in the reasoning this peculiar style of thought is conceived as deriving from a failure in the normal filtering of stimuli by dysfunctional gating systems (see Braff and Geyer, 1990; Preti, 1995a). Creative individuals, conversely, may draw advantage from higher levels of associative thinking, since they are capable of effectively processing these increased inputs without the risk of cognitive overload. Since to create consists essentially in making new combinations of associative elements, any ability which serves to bring otherwise mutually remote ideas into contiguity will facilitate a creative solution (see Mednick, 1968). This implies an extended knowledge of the argument under study (memory of ideas to be associated) and a restriction of inhibitory influences on the stimulation of remote cerebral areas which favours association. The more associations evoked by an element, the more likely it is that another element will be combined with it in a manageable form. Since inhibition or suppression (by anxiety or other more powerful competitive stimuli) would limit awareness and openess to both internal and external stimuli, their loosening would favour associative thinking, and so creativity.

Greater opportunity to combine dissociated items also leads to a greater openness to emotions and feelings. As noted earlier, this sometimes results in psychic turbulence and emotional instability, which can in itself, however, contribute to the expression of creative potential since it permits the radical re-structuring and continuous adjustment which respond to the subject's intense need for quality and novelty. In fact creative individuals are highly motivated and show a preference for activities allowing for self-expression and independence. The process of creating seems to be a highly adaptive function, and greatly contributes to success in continuously changing environments. This fact suggests that the same mental processes which can give rise to severe mental illnesses can also confer some advantage in their less dysfunctional forms which could account for the persistence in the population of maladaptive genotypes having lower fertility rates and higher mortality rates at younger ages.

7. A Kleinian Algorithm

Studies on the style of thought in schizophrenia highlight the importance of the systems that filter inputs to the production of mental associations which guide behavioural responses (see Perry and Braff, 1994; Preti, 1995b). A wide archive of data per se is not sufficient for the production of new and original ideas, whether useful or not. Each piece of information stored in the memory units (neurons) must be compared to the others, and this does not happen spontaneously. A restraint on the associative possibilities is constituted by the effective existence of circuits connecting one cerebral area (module) to other areas far from it. The existence of neural connections depends on genetic factors and on the remodelling of the neural links by developmental and environmental factors. Furthermore specific neural circuits can be activated by certain stimuli and not by others. The integration of the activated circuits, in their convergence towards a response to the stimuli, is guided by 'filtering' systems that favour the spread of the stimuli and linked responses, through inhibition of the weaker signals. An overly rigid system, however, which suppresses all under-threshold signals, can give only stereotyped responses. A more creative system might let even weaker signals pass, which enrich what Harnad called the 'symbolic grounding' of the system. These low-level signals can stimulate associations not predicted by the principal powerful signal. A self-activating system will be even more creative the emotional instability of many, though not all, creative individuals drives them towards enterprises which, by allowing the proper expression of their own potential, strengthen the Ego and reduce anxiety.

The link between a defective functioning in the neural circuits and a creative output is relevant for AI research. There are AI program that have outputs not predictable on the basis of the way they had been programmed. For example, Margaret Boden some time ago discussed the outputs from some AI musical composer programmes which had originated interesting and attractive styles of music composition of their own. These styles were not in any predictable way programmed in. If these creative results from the AI programmes were derived from some bugs, the observation of a link between creativity and mental disorders can also be extended to the AI world.

There is another aspect that has important implications for AI research. Mental disorders as a whole are rather widespread in the general population. About 25-30% of people suffer from a mental disorder severe enough to need psychiatric treatment; 1% of people suffer from a disorder of the schizophrenic spectrum, up to 10% of individuals in the general population suffer from a mood disorder. The style of thought in the general population is not uniform, and not for only cultural or social variety, but also as a consequence of profound biological differences in the functioning of neural circuits that allow mental computation. In fact some people may need programmes that 'think' in a way that is different from that of the majority of other people.

At the moment one can only imagine an AI which, like 'Wintermute' in William Gibson's 'Neuromancer', commits itself to the search for information in order to contain its grief due to the death of its creator. But an 'emotionally instable' program or machine that goes in search of lost information and looks for the opportunity to play and engage with others, like the Player Computer in 'Wargame', is already conceivable; one is merely waiting for the day when, in some remote room of a research centre there awakes an scientific realization of Hal 2000, needing the same care and attention as its forerunner did, when dreamed up by the film-maker Stanley Kubrick.

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