In psychology, schizotypy is a theoretical concept that posits a continuum of personality characteristics and experiences, ranging from normal dissociative, imaginative states to extreme states of mind related to psychosis, especially schizophrenia. The continuum of personality proposed in schizotypy is in contrast to a categorical view of psychosis, wherein psychosis is considered a particular (usually pathological) state of mind, which the person either has or does not have.
Development of the concept
The categorical view of psychosis is most associated with Emil Kraepelin, who created criteria for the medical diagnosis and classification of different forms of psychotic illness. Particularly, he made the distinction between dementia praecox (now called schizophrenia), manic depressive insanity and non-psychotic states. Modern diagnostic systems used in psychiatry (such as the DSM) maintain this categorical view.American Psychiatric Association (1994). DSM IV: Diagnostic and Statistical Manual of Mental Disorders, 4th Edition. Washington: APA.
In contrast, psychiatrist Eugen Bleuler did not believe there was a clear separation between sanity and madness, believing instead that psychosis was simply an extreme expression of thoughts and behaviours that could be present to varying degrees throughout the population.Bleuler, E. (1911). Dementia Praecox or the Group of Schizophrenias. Translated by J. Zinkin. New York: International Universities Press, Inc. (1950).
The concept of psychosis as a spectrum was further developed by psychologists such as Hans Eysenck and Gordon Claridge, who sought to understand unusual variations in thought and behaviour in terms of personality theory. Eysenck conceptualised cognitive and behavioral variations as all together forming a single personality trait, psychoticism.See, for example, Eysenck, H.J. (1992). The Definition and Meaning of Psychoticism. Personality and Individual Differences, 13, 757-785.
Meehl et al. 1964 first coined the term 'schizotypy,' and through examination of unusual experiences in the general population and clustering of symptoms in individuals diagnosed with schizophrenia. The work of Claridge suggested that this personality trait was more complex than had been previously thought and could be broken down into four factors.Bentall, R.P., Claridge, G. and Slade, P.D. (1989). The multi dimensional nature of schizotypal traits: a factor analytic study with normal subjects. British Journal of Clinical Psychology, 28, 363-375.Claridge, G., McCreery, C., Mason, O., Bentall, R., Boyle, G., Slade, P., & Popplewell, D. (1996). The factor structure of 'schizotypal' traits: A large replication study. British Journal of Clinical Psychology, 35, 103-115.
Unusual experiences: The disposition to have unusual perceptual and other cognitive experiences, such as hallucinations, magical or superstitious belief and interpretation of events (see also delusions). This factor is also often referred to as "positive schizotypy" and "cognitive-perceptual" schizotypy Cognitive disorganization: A tendency for thoughts to become derailed, disorganised or tangential (see also formal thought disorder). This factor is also often referred to as "disorganized schizotypy" Introverted anhedonia: A tendency to introverted, emotionally flat and asocial behaviour, associated with a deficiency in the ability to feel pleasure from social and physical stimulation. This factor is also often referred to as "negative schizotypy" and "schizoidia" Impulsive nonconformity: The disposition to unstable mood and behaviour particularly with regard to rules and social conventions.
The relationship between schizotypy, mental health and mental illness
Although aiming to reflect some of the features present in diagnosable mental illness, schizotypy does not necessarily imply that someone who is more schizotypal than someone else is more ill. For example, certain aspects of schizotypy may be beneficial. Both the unusual experiences and cognitive disorganisation aspects have been linked to creativity and artistic achievement.Nettle, D. (2006). Schizotypy and mental health amongst poets, visual artist, and mathematicians. Journal of Research in Personality, 40, 876-890. Also available online: Nettle, 2006 JacksonJackson, M. (1997). Benign schizotypy? The case of religious experience. In G. Claridge, ed., Schizotypy, implications for illness and health. Oxford: Oxford University Press. Pp. 227-250 proposed the concept of 'benign schizotypy' in relation to certain classes of religious experience, which he suggested might be regarded as a form of problem-solving and therefore of adaptive value. The link between positive schizotypy and certain facets of creativity^ Tsakanikos, E. & Claridge, G. (2005). More words, less words: Verbal fluency as a function of 'positive' and 'negative' schizotypy. Personality and Individual Differences, 39, 705-713 is consistent with the notion of a "healthy schizotypy", which may account for the persistence of schizophrenia-related genes in the population despite their many dysfunctional aspects. The extent of schizotypy can be measured using certain diagnostic tests, such as the O-LIFE.
However, the exact nature of the relationship between schizotypy and diagnosable psychotic illness is still controversial. One of the key concerns that researchers have had is that questionnaire-based measures of schizotypy, when analysed using factor analysis, do not suggest that schizotypy is a unified, homogeneous concept. The three main approaches have been labelled as 'quasi-dimensional', 'dimensional' and 'fully dimensional'.For a discussion of these three variant models, see McCreery, C. and Claridge, G. (2002). Healthy schizotypy: the case of out-of-the-body experiences. Personality and Individual Differences, 32, 141-154.
Each approach is sometimes used to imply that schizotypy reflects a cognitive or biological vulnerability to psychosis, although this may remain dormant and never express itself, unless triggered by appropriate environmental events or conditions (such as certain doses of drugs or high levels of stress).
Quasi-dimensional approach
The quasi-dimensional model may be traced back to Bleuler (the inventor of the term 'schizophrenia'), who commented on two types of continuity between normality and psychosis: that between the schizophrenic and their relatives, and that between the patient's premorbid and post-morbid personalities (i.e. their personality before and after the onset of overt psychosis).
On the first score he commented: 'If one observes the relatives of our patients, one often finds in them peculiarities which are qualitatively identical with those of the patients themselves, so that the disease appears to be only a quantitative increase of the anomalies seen in the parents and siblings.'Bleuler, E. (1911). Dementia Praecox or the Group of Schizophrenias. Translated by J. Zinkin. New York: International Universities Press, Inc. (1950), p. 238.
On the second point, Bleuler discusses in a number of places whether peculiarities displayed by the patient before admission to hospital should be regarded as premonitory symptoms of the disease or merely indications of a predisposition to develop it.
Despite these observations of continuity Bleuler himself remained an advocate of the disease model of schizophrenia. To this end he invoked a concept of latent schizophrenia, writing: 'In [the latent] form, we can see in nuce [in a nutshell] all the symptoms and all the combinations of symptoms which are present in the manifest types of the disease.'
Later advocates of the quasi-dimensional view of schizotypy are RadoRado, S. (1953). Dynamics and classification of disordered behaviour. American Journal of Psychiatry, 110, 406 416. and Meehl,Meehl, P.E. (1962). Schizotaxia, schizotypy, schizophrenia. American Psychologist, 17, 827 838. according to both of whom schizotypal symptoms merely represent less explicitly expressed manifestations of the underlying disease process which is schizophrenia. Rado proposed the term 'schizotype' to describe the person whose genetic make-up gave them a lifelong predisposition to schizophrenia.
The quasi-dimensional model is so called because the only dimension it postulates is that of gradations of severity or explicitness in relation to the symptoms of a disease process: namely schizophrenia.
Dimensional approach
The dimensional approach, influenced by personality theory, argues that full blown psychotic illness is just the most extreme end of the schizotypy spectrum and there is a natural continuum between people with low and high levels of schizotypy. This model is most closely associated with the work of Hans Eysenck, who regarded the person exhibiting the full-blown manifestations of psychosis as simply someone occupying the extreme upper end of his 'psychoticism' dimension.Eysenck, H.J. (1960). Classification and the problems of diagnosis. In H.J. Eysenck, ed., Handbook of Abnormal Psychology. London: Pitman. Pp.1-31.
Support for the dimensional model comes from the fact that high-scorers on measures of schizotypy may meet, or partially fulfill, the diagnostic criteria for schizophrenia spectrum disorders, such as schizophrenia, schizoaffective disorder, schizoid personality disorder and schizotypal personality disorder. Similarly, when analyzed, schizotypy traits often break down into similar groups as do symptoms from schizophreniaLiddle, P.F. (1987). The symptoms of chronic schizophrenia: A re-examination of the positive negative dichotomy. British Journal of Psychology, 151, 145 151. (although they are typically present in much less intense forms).
Fully dimensional approach
Claridge calls the latest version of his model 'the fully dimensional approach'.See, for example, Claridge, G. and Beech, T. (1995). Fully and quasi-dimensional constructions of schizotypy. In Raine, A., Lencz, T., and Mednick, S.A., Schizotypal Personality. Cambridge: Cambridge University Press. However, it might also be characterised as the hybrid or composite approach, as it incorporates elements of both the disease model and the dimensional one.
On this latest Claridge model, schizotypy is regarded as a dimension of personality, normally distributed throughout the population, as in the Eysenck model. However, schizophrenia itself is regarded as a breakdown process, quite distinct from the continuously distributed trait of schizotypy, and forming a second, graded continuum, ranging from schizotypal personality disorder to full-blown schizophrenic psychosis.
The model is characterised as fully dimensional because, not only is the personality trait of schizotypy continuously graded, but the independent continuum of the breakdown processes is also graded rather than categorical.
The fully dimensional approach argues that full blown psychosis is not just high schizotypy, but must involve other factors that make it qualitatively different and pathological.
Recent evolutionary models support a fully dimensional view of schizotypy. This framework posits schizotypy as a multifaceted continuum. Within this continuum, the phylogenetic evolution of the social brain and the coexistence of traits like openness to experience and introversion are associated with both fitness advantages (such as creativity) and an increased risk for schizotypal symptoms. Severe forms of schizotypy, consequently, represent a failure to integrate individual creativity within a social species.
Relationship to other personality traits and sociodemographics