Schizotypy
Encyclopedia
Schizotypy is a psychological
Psychology
Psychology is the study of the mind and behavior. Its immediate goal is to understand individuals and groups by both establishing general principles and researching specific cases. For many, the ultimate goal of psychology is to benefit society...

 concept which describes a continuum
Continuum (theory)
Continuum theories or models explain variation as involving a gradual quantitative transition without abrupt changes or discontinuities. It can be contrasted with 'categorical' models which propose qualitatively different states.-In physics:...

 of personality
Personality psychology
Personality psychology is a branch of psychology that studies personality and individual differences. Its areas of focus include:* Constructing a coherent picture of the individual and his or her major psychological processes...

 characteristics and experiences ranging from normal dissociative, imaginative states to more extreme states related to psychosis
Psychosis
Psychosis means abnormal condition of the mind, and is a generic psychiatric term for a mental state often described as involving a "loss of contact with reality"...

 and in particular, schizophrenia
Schizophrenia
Schizophrenia is a mental disorder characterized by a disintegration of thought processes and of emotional responsiveness. It most commonly manifests itself as auditory hallucinations, paranoid or bizarre delusions, or disorganized speech and thinking, and it is accompanied by significant social...

. This is in contrast to a categorical view of psychosis, where psychosis is considered to be a particular (usually pathological) state, that someone either has, or has not.

Development of the concept

The categorical view of psychosis is most associated with Emil Kraepelin
Emil Kraepelin
Emil Kraepelin was a German psychiatrist. H.J. Eysenck's Encyclopedia of Psychology identifies him as the founder of modern scientific psychiatry, as well as of psychopharmacology and psychiatric genetics. Kraepelin believed the chief origin of psychiatric disease to be biological and genetic...

, who created criteria for the medical diagnosis
Medical diagnosis
Medical diagnosis refers both to the process of attempting to determine or identify a possible disease or disorder , and to the opinion reached by this process...

 and classification of different forms of psychotic illness. Particularly, he made the distinction between dementia praecox
Dementia praecox
Dementia praecox refers to a chronic, deteriorating psychotic disorder characterized by rapid cognitive disintegration, usually beginning in the late teens or early adulthood. It is a term first used in 1891 in this Latin form by Arnold Pick , a professor of psychiatry at the German branch of...

 (now called schizophrenia), manic depressive insanity and non-psychotic states. Modern diagnostic systems used in psychiatry
Psychiatry
Psychiatry is the medical specialty devoted to the study and treatment of mental disorders. These mental disorders include various affective, behavioural, cognitive and perceptual abnormalities...

 (such as the DSM
Diagnostic and Statistical Manual of Mental Disorders
The Diagnostic and Statistical Manual of Mental Disorders is published by the American Psychiatric Association and provides a common language and standard criteria for the classification of mental disorders...

) maintain this categorical view.

In contrast, psychiatrist Eugen Bleuler
Eugen Bleuler
Paul Eugen Bleuler was a Swiss psychiatrist most notable for his contributions to the understanding of mental illness and for coining the term "schizophrenia."-Biography:...

 did not believe there was a clear separation between sanity
Sanity
Sanity refers to the soundness, rationality and healthiness of the human mind, as opposed to insanity. A person is sane if they are rational...

 and madness
Insanity
Insanity, craziness or madness is a spectrum of behaviors characterized by certain abnormal mental or behavioral patterns. Insanity may manifest as violations of societal norms, including becoming a danger to themselves and others, though not all such acts are considered insanity...

, believing instead that psychosis was simply an extreme expression of thoughts and behaviours that could be present to varying degrees throughout the population.

This was picked up by psychologist
Psychologist
Psychologist is a professional or academic title used by individuals who are either:* Clinical professionals who work with patients in a variety of therapeutic contexts .* Scientists conducting psychological research or teaching psychology in a college...

s such as Hans Eysenck
Hans Eysenck
Hans Jürgen Eysenck was a German-British psychologist who spent most of his career in Britain, best remembered for his work on intelligence and personality, though he worked in a wide range of areas...

 and Gordon Claridge
Gordon Claridge
Gordon Sidney Claridge is a British psychologist and author, best known for his theoretical and empirical work on the concept of schizotypy or psychosis-proneness.- Biography :...

 who sought to understand this variation in unusual thought and behaviour in terms of personality theory. This was conceptualised by Eysenck as a single personality trait named psychoticism.

Claridge named his concept schizotypy and by examining unusual experiences in the general population and the clustering of symptom
Symptom
A symptom is a departure from normal function or feeling which is noticed by a patient, indicating the presence of disease or abnormality...

s in diagnosed schizophrenia, Claridge's work suggested that this personality trait was much more complex, and could break down into four factors.
  1. Unusual experiences: The disposition to have unusual perceptual
    Perception
    Perception is the process of attaining awareness or understanding of the environment by organizing and interpreting sensory information. All perception involves signals in the nervous system, which in turn result from physical stimulation of the sense organs...

     and other cognitive experiences, such as hallucination
    Hallucination
    A hallucination, in the broadest sense of the word, is a perception in the absence of a stimulus. In a stricter sense, hallucinations are defined as perceptions in a conscious and awake state in the absence of external stimuli which have qualities of real perception, in that they are vivid,...

    s, magical or superstitious belief and interpretation of events (see also delusion
    Delusion
    A delusion is a false belief held with absolute conviction despite superior evidence. Unlike hallucinations, delusions are always pathological...

    s).
  2. Cognitive disorganization: A tendency for thoughts to become derailed, disorganised or tangential (see also formal thought disorder).
  3. Introverted anhedonia
    Anhedonia
    In psychology and psychiatry, anhedonia is defined as the inability to experience pleasure from activities usually found enjoyable, e.g. hobbies, exercise, social interaction or sexual activity....

    : A tendency to introverted, emotionally flat and asocial behaviour, associated with a deficiency in the ability to feel pleasure from social and physical stimulation.
  4. Impulsive nonconformity: The disposition to unstable mood and behaviour particularly with regard to rules and social conventions.

The relationship between schizotypy 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 academic achievement. Jackson 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.

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
Factor analysis
Factor analysis is a statistical method used to describe variability among observed, correlated variables in terms of a potentially lower number of unobserved, uncorrelated variables called factors. In other words, it is possible, for example, that variations in three or four observed variables...

, do not suggest that schizotypy is a unified, homogeneous concept. The three main approaches have been labelled as the 'quasi-dimensional', the ‘dimensional’ and the ‘fully dimensional’.

Each approach is sometimes used to imply that schizotypy reflects a cognitive or biological
Biological process
A biological process is a process of a living organism. Biological processes are made up of any number of chemical reactions or other events that results in a transformation....

 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 his or her relatives, and that between the patient’s pre- 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.’

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 Rado and Meehl, 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 him or her a life-long 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.

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
Schizophrenia
Schizophrenia is a mental disorder characterized by a disintegration of thought processes and of emotional responsiveness. It most commonly manifests itself as auditory hallucinations, paranoid or bizarre delusions, or disorganized speech and thinking, and it is accompanied by significant social...

, schizoaffective disorder
Schizoaffective disorder
Schizoaffective disorder is a psychiatric diagnosis that describes a mental disorder characterized by recurring episodes of elevated or depressed mood, or of simultaneously elevated and depressed mood, that alternate with, or occur together with, distortions in perception.Schizoaffective disorder...

, schizoid personality disorder
Schizoid personality disorder
Schizoid personality disorder is a personality disorder characterized by a lack of interest in social relationships, a tendency towards a solitary lifestyle, secretiveness, emotional coldness, and sometimes apathy, with a simultaneous rich, elaborate, and exclusively internal fantasy world...

 and schizotypal personality disorder
Schizotypal personality disorder
Schizotypal personality disorder, or simply schizotypal disorder, is a personality disorder that is characterized by a need for social isolation, anxiety in social situations, odd behavior and thinking, and often unconventional beliefs.-Genetic:...

. Similarly, when analyzed, schizotypy traits often break down into similar groups as do symptoms from schizophrenia (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’. 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.

Anhedonia

Anhedonia
Anhedonia
In psychology and psychiatry, anhedonia is defined as the inability to experience pleasure from activities usually found enjoyable, e.g. hobbies, exercise, social interaction or sexual activity....

, or a reduced ability to experience pleasure, is a feature of full-blown schizophrenia that was commented on by both Kraepelin and Bleuler. However, they regarded it as just one among a number of features that tended to characterise the ‘deterioration’, as they saw it, of the schizophrenic’s emotional life. In other words, it was an effect, rather than a cause, of the disease process.

Rado reversed this way of thinking, and ascribed anhedonia a causal role. He considered that the crucial neural deficit in the schizotype was an ‘integrative pleasure deficiency’, i.e. an innate deficiency in the ability to experience pleasure. Meehl took on this view, and attempted to relate this deficiency to abnormality in the dopamine
Dopamine
Dopamine is a catecholamine neurotransmitter present in a wide variety of animals, including both vertebrates and invertebrates. In the brain, this substituted phenethylamine functions as a neurotransmitter, activating the five known types of dopamine receptors—D1, D2, D3, D4, and D5—and their...

 system in the brain, which is implicated in the human reward system
Reward system
In neuroscience, the reward system is a collection of brain structures which attempts to regulate and control behavior by inducing pleasurable effects...

.

Questionnaire research on schizotypy in normal subjects is ambiguous with regard to the causal role, if any, of anhedonia. Nettle and McCreery and Claridge found that high schizotypes as measured by factor 1 (above) scored lower than controls on the introverted anhedonia factor, as if they were particularly enjoying life.

Various writers, including Kelley and Coursey and L.J. and J.P. Chapman suggest that anhedonia, if present as a pre-existent trait in a person, may act as a potentiating factor, whereas a high capacity for hedonic enjoyment might act as a protecting one.

Weakness of inhibitory mechanisms

Various lines of evidence from experimental psychology have suggested a relative weakness of inhibitory mechanisms may be a characteristic of the schizotypal nervous system.

Negative priming

A number of studies have found that high schizotypes, as measured by questionnaire, show less negative priming
Negative Priming
Negative Priming is the implicit memory effect in which prior exposure to a stimulus unfavorably influences the response to the same stimulus. It falls under the category of priming, which is a memory effect in which exposure to a stimulus influences response to a later stimulus without any...

 than controls. Negative priming is said to occur when a person reacts more slowly than usual to a stimulus which has previously been presented as a distractor and which has therefore had to be ignored. Beech interprets the relative weakness of the negative priming effect in schizotypes as a sign that ‘inhibition of distracting information is reduced in schizophrenia and high schizotypes’.

The reduced negative priming shown by high schizotypes has the interesting effect that they actually perform better on certain tasks (those that require them to respond to previously ignored stimuli) than low schizotypes. This phenomenon may be of significance in the relation to the question of why schizotypy, and indeed schizophrenia itself, is not progressively ‘weeded out’ by the process of natural selection
Natural selection
Natural selection is the nonrandom process by which biologic traits become either more or less common in a population as a function of differential reproduction of their bearers. It is a key mechanism of evolution....

.

SAWCI

The phenomenon of semantic activation without conscious identification (SAWCI) is said to be displayed when a person shows a priming effect from the processing of consciously undetectable words. For example, a person who has just been shown the word ‘giraffe’, but at a speed at which he or she was not able consciously to report what it was, may nevertheless identify more quickly than usual another animal word on the next trial. Evans found that high schizotypes showed a greater priming effect than controls in such a situation. She argued that this could be accounted for by a relative weakness of inhibitory mechanisms in the semantic networks of high schizotypes.

Abnormalities of arousal

Claridge suggested that one consequence of a weakness of inhibitory mechanisms in high schizotypes and schizophrenics might be a relative failure of homeostasis
Homeostasis
Homeostasis is the property of a system that regulates its internal environment and tends to maintain a stable, constant condition of properties like temperature or pH...

 in the central nervous system. This, it was proposed, could lead, both to lability
Lability
Lability refers to something that is constantly undergoing change or something that is likely to undergo change.-Chemistry:The term is used to describe a relatively unstable and transient chemical species...

 of arousal
Arousal
Arousal is a physiological and psychological state of being awake or reactive to stimuli. It involves the activation of the reticular activating system in the brain stem, the autonomic nervous system and the endocrine system, leading to increased heart rate and blood pressure and a condition of...

, and to dissociation of arousal in different parts of the nervous system.

Dissociation of different arousal systems

Claridge and co-workers have found various types of abnormal co-variation between different psychophysiological variables in schizotypes, including between measures of cortical and autonomic
Autonomic nervous system
The autonomic nervous system is the part of the peripheral nervous system that acts as a control system functioning largely below the level of consciousness, and controls visceral functions. The ANS affects heart rate, digestion, respiration rate, salivation, perspiration, diameter of the pupils,...

 arousal.

McCreery and Claridge found evidence of a relative activation of the right cerebral hemisphere
Cerebral hemisphere
A cerebral hemisphere is one of the two regions of the eutherian brain that are delineated by the median plane, . The brain can thus be described as being divided into left and right cerebral hemispheres. Each of these hemispheres has an outer layer of grey matter called the cerebral cortex that is...

 as compared with the left in high schizotypes attempting to induce a hallucinatory episode in the laboratory. This suggested a relative dissociation
Dissociation
Dissociation is an altered state of consciousness characterized by partial or complete disruption of the normal integration of a person’s normal conscious or psychological functioning. Dissociation is most commonly experienced as a subjective perception of one's consciousness being detached from...

 of arousal between the two hemispheres in such people as compared with controls.

Hyperarousal

A failure of homeostasis in the central nervous system could lead to episodes of hyper-arousal. Oswald has pointed out that extreme stress and hyper-arousal can lead to sleep as a provoked reaction. McCreery has suggested that this could account for the phenomenological
Phenomenology (psychology)
Phenomenology is an approach to psychological subject matter that has its roots in the philosophical work of Edmund Husserl. Early phenomenologists such as Husserl, Jean-Paul Sartre, and Maurice Merleau-Ponty conducted their own psychological investigations in the early 20th century...

 similarities between Stage 1 sleep and psychosis, which include hallucinations, delusions, and flattened or inappropriate affect (emotions). On this model, high schizotypes and schizophrenics are people who are liable to what Oswald calls ‘micro-sleeps’, or intrusions of Stage 1 sleep
Sleep
Sleep is a naturally recurring state characterized by reduced or absent consciousness, relatively suspended sensory activity, and inactivity of nearly all voluntary muscles. It is distinguished from quiet wakefulness by a decreased ability to react to stimuli, and is more easily reversible than...

 phenomena into waking consciousness, on account of their tendency to high arousal.

In support of this view McCreery points to the high correlation that has been found to exist between scores on the Chapmans’ Perceptual Aberration scale, which measures proneness to perceptual anomalies such as hallucinations, and the Chapmans’ Hypomania scale, which measures a tendency to episodes of heightened arousal. This correlation is found despite the fact that there is no overlap of item content between the two scales.

In the clinical field there is also the paradoxical finding of Stevens and Darbyshire, that schizophrenic patients exhibiting the symptom of catatonia
Catatonia
Catatonia is a state of neurogenic motor immobility, and behavioral abnormality manifested by stupor. It was first described in 1874: Die Katatonie oder das Spannungsirresein ....

 can be aroused from their apparent stupor by the administration of sedative rather than stimulant drugs. They wrote: ‘The psychic state in catatonic schizophrenia can be described as one of great excitement (i.e., hyperalertness)[…] The inhibition of activity apparently does not alter the inner seething excitement.'

It is argued that such a view would be consistent with the model that suggests schizophrenics and high schizotypes are people with a tendency to hyper-arousal.

See also

  • Apparitional experience
    Apparitional experience
    In psychology and parapsychology, an apparitional experience is an anomalous, quasi-perceptual experience.It is characterized by the apparent perception of either a living being or an inanimate object without there being any material stimulus for such a perception...

  • Hallucinations
  • Hallucinations in the sane
    Hallucinations in the sane
    A hallucination may occur in a person in a state of good mental and physical health, even in the apparent absence of a transient trigger factor such as fatigue, intoxication or sensory deprivation....

  • Psychosis
    Psychosis
    Psychosis means abnormal condition of the mind, and is a generic psychiatric term for a mental state often described as involving a "loss of contact with reality"...

  • Psychoticism
    Psychoticism
    Psychoticism is one of the three traits used by the psychologist Hans Eysenck in his P-E-N model model of personality. Psychoticism refers to a personality pattern typified by aggressiveness and interpersonal hostility.High levels of this trait were believed by Eysenck to be linked to increased...

  • Schizoaffective disorder
    Schizoaffective disorder
    Schizoaffective disorder is a psychiatric diagnosis that describes a mental disorder characterized by recurring episodes of elevated or depressed mood, or of simultaneously elevated and depressed mood, that alternate with, or occur together with, distortions in perception.Schizoaffective disorder...

  • Schizophrenia
    Schizophrenia
    Schizophrenia is a mental disorder characterized by a disintegration of thought processes and of emotional responsiveness. It most commonly manifests itself as auditory hallucinations, paranoid or bizarre delusions, or disorganized speech and thinking, and it is accompanied by significant social...

  • Schizotypal personality disorder
    Schizotypal personality disorder
    Schizotypal personality disorder, or simply schizotypal disorder, is a personality disorder that is characterized by a need for social isolation, anxiety in social situations, odd behavior and thinking, and often unconventional beliefs.-Genetic:...

  • Transliminality
    Transliminality
    Transliminality was a concept introduced by the parapsychologist Michael Thalbourne, an Australian psychologist who is based at the University of Adelaide...


Further reading

  • Claridge, G. (1997) Schizotypy: Implications for Illness and Health. Oxford University Press. ISBN 0-19-852353-X
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