Schizotypy

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.<ref>American Psychiatric Association (1994). DSM IV: Diagnostic and Statistical Manual of Mental Disorders, 4th Edition. Washington: APA.</ref>

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.<ref name="Bleuler, E. 1911">Bleuler, E. (1911). Dementia Praecox or the Group of Schizophrenias. Translated by J. Zinkin. New York: International Universities Press, Inc. (1950).</ref>

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.<ref>See, for example, Eysenck, H.J. (1992). The Definition and Meaning of Psychoticism. Personality and Individual Differences, 13, 757-785.</ref>

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.<ref>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.</ref><ref name="ClaridgeMcCreery">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.</ref>

1. 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
2. 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"
3. 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"
4. 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.<ref name="Nettle, 2006">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 Template:Webarchive</ref> Jackson<ref>Jackson, 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</ref> 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<ref>^ 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</ref> 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.<ref>Template:Cite journal</ref>

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'.<ref>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.</ref>

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<ref name="Bleuler, E. 1911"/> (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.'<ref name="Bleuler, E. 1911 p. 238">Bleuler, E. (1911). Dementia Praecox or the Group of Schizophrenias. Translated by J. Zinkin. New York: International Universities Press, Inc. (1950), p. 238.</ref>

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.'<ref name="Bleuler, E. 1911 p. 238"/>

Later advocates of the quasi-dimensional view of schizotypy are Rado<ref>Rado, S. (1953). Dynamics and classification of disordered behaviour. American Journal of Psychiatry, 110, 406 416.</ref> and Meehl,<ref>Meehl, P.E. (1962). Schizotaxia, schizotypy, schizophrenia. American Psychologist, 17, 827 838. </ref> 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.<ref>Eysenck, H.J. (1960). Classification and the problems of diagnosis. In H.J. Eysenck, ed., Handbook of Abnormal Psychology. London: Pitman. Pp.1-31.</ref>

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 schizophrenia<ref>Liddle, P.F. (1987). The symptoms of chronic schizophrenia: A re-examination of the positive negative dichotomy. British Journal of Psychology, 151, 145 151.</ref> (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'.<ref>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.</ref> 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.<ref>Template:Cite journal</ref><ref>Template:Citation</ref> 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

Many research studies have examined the relationship between schizotypy and various standard models of personality, such as the five factor model.<ref name=hierarchic>Template:Cite journal</ref> Research has linked the unusual experiences factor to high neuroticism and openness to experience. Unusual experience in combination with positive affectivity also appears to predict religiosity/spirituality.<ref>Template:Cite journal</ref> One study found that a moderate level of unusual experiences predicted increased religiosity, but a high level of unusual experiences predicted lower religiosity, and that impulsive non-conformity was associated with lower religiosity, as well as lower values of tradition and conformity.<ref>Template:Cite journal</ref> The introvertive anhedonia factor has been linked to high neuroticism and low extraversion. The cognitive disorganisation factor as well as the impulsive non-conformity factor have been linked to low conscientiousness. It has been argued that these findings provide evidence for a fully dimensional model of schizotypy and that there is a continuum between normal personality and schizotypy.<ref name=hierarchic/>

Relationships between schizotypy and the Temperament and Character Inventory have also been examined.<ref name=laidlaw>Template:Cite journal</ref> Self-transcendence, a trait associated with openness to "spiritual" ideas and experiences, has moderate positive associations with schizotypy, particularly with unusual experiences. Cloninger described the specific combination of high self-transcendence, low cooperativeness, and low self-directedness as a "schizotypal personality style"<ref name=laidlaw/> and research has found that this specific combination of traits is associated with a "high risk" of schizotypy.<ref name=Danelluzo>Template:Cite journal</ref> Low cooperativeness and self-directedness combined with high self-transcendence may result in openness to odd or unusual ideas and behaviours associated with distorted perceptions of reality.<ref name=laidlaw/> On the other hand, high levels of cooperativeness and self-directedness may protect against the schizotypal tendencies associated with high self-transcendence.<ref name=siblings>Template:Cite journal</ref>

One study examined the relationship between the dimensional MBTI scales, and found that schizotypy was associated with a tendency toward introversion, intuition (as opposed to sensing), thinking (as opposed to feeling), and prospecting (as opposed to judging), which can be represented by the "INTP" personality type in the MBTI model.<ref name="Coolidge Segal Hook Yamazaki 2001 pp. 33–36">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Intuition is conceptually similar to the Big Five "openness to experience" trait which is thought to be increased in schizotypy, thinking represents the tendency to prefer objectivity and evidence in making decisions and forming beliefs and is conceptually similar to the lower level "intellect" factor of openness in the Big Five, and prospecting is conceptually similar to low conscientiousness in the Big Five.

Schizotypy shows positive associations with traits that are associated with fast life history strategies, including increased sociosexuality (characterized by increased effort for short term sexual relationships, lower effort for long term sexual relationships, increased total amount of sexual partners, and lower sexual disgust) and impulsivity.<ref>Template:Cite journal</ref><ref name="sciencedirect.com">Template:Cite journal</ref>

Personality disorders

Schizotypy shows positive associations with overall psychopathy, however when considering the primary and secondary factors of psychopathy, schizotypy is associated with lower primary psychopathy (also called fearless dominance) and higher secondary psychopathy (also called self-centered impulsivity, or disinhibition).<ref>Template:Cite journal</ref> Narcissism is negatively associated with schizotypy,<ref>Template:Cite journal</ref> (though persons high in schizotypy may experience grandiose delusions<ref>Template:Cite journal</ref> along with idionomia,<ref name="psycnet.apa.org">Template:Cite journal</ref> a sense of deviance and enlightenment, which may be mistaken for narcissism), and borderline personality traits are positively associated with schizotypy <ref>Template:Cite journal</ref> as well hypomanic personality traits.<ref>Template:Cite journal</ref> Schizotypy also shows positive relationships with schizoid, paranoid, and avoidant personality traits,<ref>Template:Cite journal</ref> and a negative relationship with obsessive-compulsive personality traits (particularly with disorganized schizotypy).<ref>Template:Cite journal</ref> In contrast to obsessive-compulsive personality disorder, obsessive-compulsive disorder shows a positive relationship with schizotypy.<ref name="Do the traits of autism-spectrum ov">Template:Cite journal</ref>

Cognitive function

There is evidence that schizotypy correlates with differentially enhanced and impaired aspects of cognitive function. These findings include schizotypy being positively associated with enhanced global processing over local processing,<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> lower latent inhibition,<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> attention & memory deficits,<ref>Template:Cite journal</ref> enhanced creativity & imagination,<ref>Template:Cite journal</ref> and enhanced associative thinking.<ref name="academic.oup.com">Template:Cite journal</ref>

Autism

Correlational studies of schizotypy and autistic traits tend to find positive correlations, most strongly with negative schizotypy, to a lesser extent disorganized schizotypy, and weak, absent, or negative correlations with positive schizotypy.<ref>Template:Cite journal</ref><ref name="Do the traits of autism-spectrum ov"/><ref name="Validation of the French Autism Spe">Template:Cite journal</ref> Diagnosed schizophrenia and autism spectrum disorder (ASD) also overlap statistically.

However, several researchers have suggested that positive correlations between schizotypy and autism are not necessarily evidence of overlap, but rather are due to a lack of specificity of measurements for autistic and schizotypal traits, and the confounding variable of social difficulties and social-cognitive dysfunction which occur in both autism and schizotypy.<ref name="cambridge.org">Template:Cite journal</ref><ref name="Evolutionary psychopathology: A uni">Template:Cite journal</ref><ref name="philpapers.org">Template:Cite journal</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>Template:Cite journal</ref> Researchers have suggested that high comorbidity between diagnosed ASD and schizophrenia are highly unreliable and misleading due to a severe inadequacy of the DSM and diagnostic interviews for differential diagnosis.<ref>Template:Cite book</ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref name="researchgate.net">Template:Cite book</ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> Studies which show apparent overlap between the causes of autism and the causes of schizotypy also have significant methodological issues.<ref name="Konstantin Nordgaard Henriksen 2023 pp. 1–12">Template:Cite journal</ref><ref name="cambridge.org" /><ref name="Stanghellini Ballerini 2011 pp. 183–192">Template:Cite journal</ref>

Multiple evolutionary theories of schizotypy place schizotypy and autistic traits at opposite poles of a continuum, with relation to traits such as theory of mind,<ref name="philpapers.org" /><ref>Template:Cite journal</ref> life history and mating strategies,<ref name="Evolutionary psychopathology: A uni" /> "mentalistic" or creative cognition and "mechanistic" cognition,<ref>Template:Cite journal</ref><ref name="researchgate.net" /> and predictive processing.<ref name="Autistic-Like Traits and Positive S">Template:Cite journal</ref> In agreement with this, schizotypy (particularly positive, impulsive, and disorganized schizotypy) shows a negative association with autistic traits when controlling for social difficulty, which has been well replicated across different countries, scales, methods, and independent research teams, and a diametric autism-schizotypy continuum factor emerges through factor analysis.<ref name="Validation of the French Autism Spe" /><ref>Template:Cite journal</ref><ref name="sciencedirect.com" /><ref>Template:Cite journal</ref><ref name="Subclinical schizotypal vs. autisti">Template:Cite journal</ref><ref name="ZhangZhouWang2019">Template:Cite journal</ref><ref name="ZhouYangGong2019">Template:Cite journal</ref> Notably, some studies find a direct negative association with positive schizotypy and autistic traits even when social difficulty is not controlled for.<ref name="HudsonSantavirtaPutkinen2022">Template:Citation</ref><ref name="Do the traits of autism-spectrum ov" />

Some researchers have interpreted these findings as indicating that autistic and schizotypal traits are both overlapping and diametrical in different aspects, with autistic social difficulties and negative schizotypal symptoms being a shared dimension, and positive, disorganized, and impulsive schizotypy as a dimension that is diametrically opposed to autism.<ref name="Subclinical schizotypal vs. autisti" /><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Possible biological bases of schizotypy

Cognitive imbalances and tradeoffs

Predictive processing

Andersen (2022) put forth a model of schizotypy based on the predictive processing framework, where lower importance is attributed to sensory prediction errors for updating beliefs in individuals with high schizotypy.<ref name="Autistic-Like Traits and Positive S"/> Essentially, this means that schizotypy is a cognitive-perceptual specialization for processing chaotic and noisy data, where patterns and relationships exist but can only be detected if minor inconsistencies are ignored (i.e., focusing on the 'big picture'). Andersen suggests that a tradeoff exists in predictive processing, where giving higher weight to prediction errors prevents the detection of false patterns (i.e. apophenia) at the cost of being unable to detect higher level patterns, and giving lower weight to prediction errors allows for the detection of higher level patterns at the cost of occasionally detecting patterns that don't exist, as in delusions and hallucinations that occur in schizotypy. This model explains features of schizotypy and previous models of schizotypy, such as the hyper-mentalizing model originally proposed by Abu-Akel (1999),<ref name="philpapers.org"/> hyper-associative cognition,<ref>Template:Cite journal</ref> the hyper-imagination model by Crespi (2016),<ref>Template:Cite journal</ref> antagonomia (acting in ways directly opposing societal values) and idiosyncratic worldviews,<ref name="psycnet.apa.org"/> attentional differences such as latent inhibition,<ref name="Shrira, A. 2009">Shrira, A. & Tsakanikos, E. (2009). Latent inhibition as a function of schizotypal symptoms: evidence for a bi-directional model. Personality and Individual Differences, 47, 922-927.</ref> hyper-openness,<ref>Template:Cite journal</ref> increased exploratory behavior,<ref>Template:Cite journal</ref> and enhanced cognitive abilities in insight problem solving, creativity, and global processing.<ref>Template:Cite journal</ref>

Hormone abnormalities

Oxytocin & testosterone

There is some evidence to suggest that abnormalities in the regulation of oxytocin and testosterone are related to schizotypy. Crespi (2015) provides evidence that schizophrenia and related disorders may involve increased or dysregulated oxytocin, and relatively decreased testosterone, leading to "hyper-developed" social cognition,<ref>Template:Cite journal</ref> although Crespi's model of schizotypy has been criticized.<ref>Template:Cite journal</ref> Evidence for oxytocin's role in schizotypy includes genes associated with higher oxytocin levels being associated with higher levels of positive schizotypy,<ref>Template:Cite journal</ref> blood oxytocin levels positively associated with schizotypy in females,<ref>Template:Cite journal</ref> ratio of genes associated with low testosterone and high oxytocin positively associated with schizotypy and negatively with autistic traits,<ref>Template:Cite journal</ref> oxytocin levels being associated with higher social anxiety,<ref>Template:Cite journal</ref> and oxytocin being associated with global processing, divergent thinking, and creativity,<ref>Template:Cite journal</ref> which are also strongly associated with schizotypy.<ref name="academic.oup.com"/>

Anhedonia

Anhedonia, or a reduced ability to experience pleasure, is a feature of full-blown schizophrenia that was commented on by both Kraepelin<ref>Kraepelin, E. (1913). Dementia Praecox and Paraphrenia. Translated by R.M. Barclay. Edinburgh: Livingston, (1919).</ref> and Bleuler.<ref name="Bleuler, E. 1911"/> 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<ref>Rado, S. (1953). Dynamics and classification of disordered behaviour. American Journal of Psychiatry, 110, 406 416.</ref> 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<ref>Meehl, P.E. (1962). Schizotaxia, schizotypy, schizophrenia. American Psychologist, 17, 827 838.</ref> took on this view, and attempted to relate this deficiency to abnormality in the dopamine system in the brain, which is implicated in the human reward system.

Questionnaire research on schizotypy in normal subjects is ambiguous with regard to the causal role, if any, of anhedonia. Nettle<ref name="Nettle, 2006"/> and McCreery and Claridge<ref>McCreery, C. and Claridge, G. (2002). Healthy schizotypy: the case of out-of-the-body experiences. Personality and Individual Differences, 32, 141-154.</ref> 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<ref>Kelley, M.P. and Coursey, R.D. (1992). Factor structure of schizotypy scales. Personality and Individual Differences, 13, 723-731.</ref> and L.J. and J.P. Chapman<ref>Chapman, L.J., Chapman, J.P., Kwapil, T.R, Eckblad, M., & Zinser, M.C. (1994). Putatively psychosis-prone subjects 10 years later. Journal of Abnormal Psychology, 103, 171 183.</ref> 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.

Evolutionary Perspectives

Within evolutionary psychology and evolutionary psychiatry, schizotypy is viewed as part of a spectrum of variation potentially maintained by evolutionary trade-offs rather than as purely maladaptive.<ref>Template:Cite journal</ref> Moderate expressions of schizotypal traits—such as divergent thinking, unusual associations, or social intuition—may have conferred adaptive advantages related to creativity, exploration, or mating success, even though extreme forms can lead to functional impairment or psychosis.<ref>Template:Cite journal</ref> Hypotheses including sexual selection models, the imprinted brain hypothesis, and life-history theory suggest that schizotypy may represent one pole of an evolved cognitive continuum, balanced by opposite traits such as autism. These accounts propose that selection pressures preserved schizotypal traits through their benefits in communication and innovation, offsetting costs at the pathological extreme.

Weakness of inhibitory mechanisms

Negative priming

Negative priming is "the ability of a preceding stimulus to inhibit the response to a subsequent stimulus."<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Individuals diagnosed with schizophrenia or schizotypy exhibit "reduced or abolished NP [negative priming], especially in the presence of positive symptomatology, acute psychosis, high severity of symptoms, and/or lack of medication."<ref>Template:Cite journal</ref>

Semantic activation without conscious identification

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<ref>Evans, J.L. (1992). Schizotypy and Preconscious Processing. Unpublished D.Phil. thesis, University of Oxford.</ref> 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.

Attention, working memory, and executive functions

Schizotypy symptoms have been related to deficits in executive functions, which entails the psychological processes that supersede habitual inclinations with novel responses and behaviors to fulfill important goals. In particular, when schizotypy is elevated, the ability to filter out task-irrelevant stimuli may be impaired.<ref name="Shrira, A. 2009"/> That is, participants who score highly on schizotypy tend to fail to ignore a previously preexposed, non-reinforced stimulus as compared to a non-preexposed, novel and potentially important event.

Enhanced performance on verbal fluency has been associated with high levels of positive schizotypy, i.e. increased reports of hallucination-like experiences, delusional ideation, and perceptual aberrations. However, decreased performance was associated with negative schizotypy, such as anhedonia.<ref>Tsakanikos, E. & Claridge, G. (2005). Less words, more words: psychometric schizotypy and verbal fluency. Personality and Individual Differences, 39, 705-713.</ref>

Many studies have also shown that individuals who exhibit schizotypy features demonstrate deficits in attention and working memory.<ref>^ Beech, A.R. and Claridge, G.S. (1987). Individual differences in negative priming: Relations with schizotypal personality traits. British Journal of Clinical Psychology, 78, 349-356.</ref><ref>Tsakanikos, E. (2004). Logical reasoning in schizotypal personality. Personality and Individual Differences, 37, 1717-1726.</ref><ref>Tsakanikos, E., & Reed, P. (2003). Visuo-spatial processing and dimensions of schizotypy: figure-ground segregation as a function of psychotic-like features. Personality and Individual Differences, 35, 703-712.</ref><ref>Tsakanikos, E. & Reed, P. (2005). Dimensional approaches to experimental psychopathology: shift learning and schizotypic traits in college students. Journal of Behavior Therapy and Experimental Psychiatry, 36, 300-312.</ref>

Abnormalities of arousal

Claridge<ref>Claridge, G.S. (1967). Personality and Arousal. Oxford: Pergamon.</ref> suggested that one consequence of a weakness of inhibitory mechanisms in high schizotypes and schizophrenics might be a relative failure of homeostasis in the central nervous system. It was proposed that this could lead to both lability of arousal and dissociation of arousal in different parts of the nervous system.

Dissociation of different arousal systems

Claridge and co-workers<ref>Claridge, G.S. and Clark, K.H. (1982). Covariation between two flash threshold and skin conductance level in first breakdown schizophrenics: Relationships in drug free patients and effects of treatment. Psychiatry Research, 6, 371 380.</ref><ref>Claridge, G.S. and Birchall, P.M.A. (1978). Bishop, Eysenck, Block and psychoticism. Journal of Abnormal Psychology, 87, 664 668.</ref><ref>Claridge, G.S., Robinson, D.L. and Birchall, P.M.A. (1985). Psychophysiological evidence of `psychoticism' in schizophrenics' relatives. Personality and Individual Differences, 6, 1 10.</ref> have found various types of abnormal co-variation between different psychophysiological variables in schizotypes, including between measures of cortical and autonomic arousal.

McCreery and Claridge<ref>McCreery, C., and Claridge, G. (1996). 'A study of hallucination in normal subjects – II. Electrophysiological data'. Personality and Individual Differences, 21, 749-758.</ref> found evidence of a relative activation of the right cerebral hemisphere as compared with the left in high schizotypes attempting to induce a hallucinatory episode in the laboratory. This suggested a relative dissociation 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<ref>Oswald, I. (1962). Sleeping and Waking: Physiology and Psychology. Amsterdam: Elsevier.</ref> has pointed out that extreme stress and hyper-arousal can lead to sleep as a provoked reaction. McCreery<ref>McCreery, C. (1997). Hallucinations and arousability: pointers to a theory of psychosis. In Claridge, G. (ed.): Schizotypy, Implications for Illness and Health. Oxford: Oxford University Press.</ref><ref>McCreery, C. (2008). Dreams and psychosis: a new look at an old hypothesis. Psychological Paper No. 2008-1. Oxford: Oxford Forum. Also available online: McCreery 2008 Template:Webarchive</ref> has suggested that this could account for the phenomenological 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 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<ref name="ClaridgeMcCreery" /> between scores on the Chapmans' Perceptual Aberration scale,<ref>Chapman, L.J., Chapman, J.P. and Raulin, M.L. (1978). Body image aberration in schizophrenia. Journal of Abnormal Psychology, 87, 399 407.</ref> which measures proneness to perceptual anomalies such as hallucinations, and the Chapmans' Hypomania scale,<ref>Eckblad, M. and Chapman, L.J. (1986). Development and validation of a scale for hypomanic personality. Journal of Abnormal Personality, 95, 217 233.</ref> 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,<ref>Stevens, J.M. and Darbyshire, A.J. (1958). Shifts along the alert-repose continuum during remission of catatonic 'stupor' with amobarbitol. Psychosomatic Medicine, 20, 99-107.</ref> that schizophrenic patients exhibiting the symptom of catatonia 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.

Aberrant salience hypothesis

{{#invoke:Labelled list hatnote|labelledList|Main article|Main articles|Main page|Main pages}} Kapur (2003) proposed that a hyperdopaminergic state, at a "brain" level of description, leads to an aberrant assignment of salience to the elements of one's experience, at a "mind" level.<ref>Kapur, S. (2003). Psychosis as a state of aberrant salience: a framework linking biology, phenomenology, and pharmacology in schizophrenia. American Journal of Psychiatry,160, 13–23.</ref> Dopamine mediates the conversion of the neural representation of an external stimulus from a neutral bit of information into an attractive or aversive entity, i.e. a salient event. Symptoms of schizophrenia and schizotypy may arise out of 'the aberrant assignment of salience to external objects and internal representations'; and antipsychotic medications may reduce positive symptoms by attenuating aberrant motivational salience, via blockade of the Dopamine D2 receptors (Kapur, 2003). There is no evidence however on a link between attentional irregularities and enhanced stimulus salience in schizotypy.<ref>Tsakanikos, E. (2004). Latent inhibition, visual pop-out and schizotypy: is disruption of latent inhibition due to enhanced stimulus salience?Personality and Individual Differences, 37, 1347-1358.</ref>

See also

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Further reading

• Cheli, S., Lysaker, P. H. (2023). A Dimensional Approach to Schizotypy. Conceptualization and Treatment. Springer International Publishing. Template:ISBN
• Claridge, G. (1997) Schizotypy: Implications for Illness and Health. Oxford University Press. Template:ISBN
• Claridge, G., Mason, O. (2015). Schizotypy. New Dimensions. Taylor & Francis. Template:ISBN
• Lenzenweger, M. F. (2011). Schizotypy and Schizophrenia. The View from Experimental Psychopathology. Guilford Publications. Template:ISBN