Elsevier

Schizophrenia Research

Volume 80, Issues 2–3, 15 December 2005, Pages 271-282
Schizophrenia Research

Verbal creativity and schizotypal personality in relation to prefrontal hemispheric laterality: A behavioral and near-infrared optical imaging study

https://doi.org/10.1016/j.schres.2005.06.016Get rights and content

Abstract

Although anecdotal and correlational results have suggested a reliable relationship between creativity and psychosis, few studies have examined this relationship using empirical methods. In addition, little is known about the neural substrates of creative thinking. We investigated the creative thinking process in relation to schizotypal personality, schizophrenia and prefrontal hemispheric laterality using behavioral and near-infrared optical spectroscopy (NIRS) methods. Schizophrenic, psychometrically ascertained schizotypal, and healthy control subjects (all right-handed) participated in a novel “alternate uses” task designed to assess divergent thinking (DT) ability. The DT task required subjects to generate “uses” for conventional and ambiguous objects. Prefrontal activity was measured using NIRS while subjects were engaged in DT vs. a cognitive control task in a subset of the subjects. Behavioral data indicated that schizotypes had enhanced DT ability compared with schizophrenic and control subjects, who showed similar performance overall. NIRS data showed that DT was associated with bilateral prefrontal cortex (PFC) activation, but the right PFC particularly contributed to the enhanced creative thinking in psychometric schizotypes compared with the other two groups. Thus, creative thinking seems to robustly recruit bilateral PFC, but it is the right PFC that is preferentially activated in schizotypes in relation to their enhanced DT.

Introduction

Archival and biographic data from individuals with psychotic illnesses and from their relatives have supported the association between creativity and mental illness; however, few studies have used hypothesis-driven and empirical methods to examine the link between creativity and psychosis.

There is overwhelming support for a positive relationship between creativity and schizotypy (cf. Eysenck and Furnham, 1993, Gianotti et al., 2001, Kline and Cooper, 1986, Merten and Fischer, 1999, O'Reilly et al., 2001, Poreh et al., 1994, Rawlings and Toogood, 1997, Rushton, 1990, Rust et al., 1989, Weinstein and Graves, 2001, Weinstein and Graves, 2002, Woody and Claridge, 1977, Zanes et al., 1998) but currently, there is little support for enhanced creative ability in schizophrenics (Andreasen and Powers, 1975, Cropley and Sikand, 1973, Keefe and Magaro, 1980, Shimkunas and Murray, 1974). Yet, several studies using retrospective analyses of birth records, found support for increased creativity in the relatives of schizophrenic individuals, rather than in the probands themselves (Karlsson, 1970, Karlsson, 1984). These results suggest that enhanced creativity may be masked by the psychotic illness in the probands but can be detected in those individuals who share a latent liability for psychosis. Examining a clearly defined aspect of creativity in relation to brain laterality in schizotypal individuals or those at high risk for schizophrenia is warranted.

Two major established theories define the process and products of creative thinking. Guilford (1959) has emphasized divergent thinking (DT) and the use of generative, flexible responses that redefine or elaborate upon an existing product or idea. Mednick (1962) built upon this definition, showing that creative thinking emphasizes generating novel associations. DT has emerged as a valid core element in the creative thinking process (Bartlett and Davis, 1974, Torrance, 1988).

The spread of activation through semantic networks is central to verbal DT models. When indirectly related associations are activated, creative solutions are thought to be enhanced (Mohr et al., 2001, Pizzagalli et al., 2001). Schizophrenic patients (Spitzer et al., 1993, Weisbrod et al., 1998) and schizotypes (Gianotti et al., 2001, Mohr et al., 2001, Pizzagalli et al., 2001) show increased indirect semantic priming, suggesting that semantic organization may be altered and accessing indirect connections may be easier for psychosis-prone individuals. It is also possible that greater spreading activation could increase across hemispheres in individuals who have decreased cerebral lateralization. The right frontal lobe is involved in generating unusual or distant verbal associations while the left frontal lobe is involved in generating “usual” associations (Kiefer et al., 1998, Seger et al., 2000) Enhanced creativity and schizotypy may be associated with increased interhemispheric transfer (Miran and Miran, 1984), thereby making more efficient use of bilateral networks to generate associations.

Increased hemispheric interactions and reduced laterality may be central to both schizophrenia and creativity. Divergent and creative thinking may be characterized by increased cooperation of the two hemispheres (Atchley et al., 1999, Bekhtereva et al., 2000, Carlsson et al., 2000), and reduced hemispheric dominance has been linked to creativity (Claridge and Broks, 1984). Schizophrenia is associated with reduced functional and structural laterality. There is robust support for mixed handedness in schizophrenia (Cannon et al., 1995, Crow et al., 1996, DeLisi et al., 2002) and in schizotypes (Chapman and Chapman, 1987, Claridge et al., 1998, Kim et al., 1992, Richardson, 1994) rather than pure left-handedness (Shaw et al., 2001). Mixed handedness is associated with decreased cerebral lateralization, schizotypy, and enhanced creativity (Claridge and Broks, 1984). However, several neuroimaging and lesion studies also report specific RH correlates of creative thinking (Bowden and Beeman, 2003, Jung-Beeman et al., 2004, Martindale et al., 1984, Miller and Tippett, 1996, Razumnikova, 2004), although such unilateral functional preference may also be an outcome of intrahemispheric cooperation (Petsche, 1996, Razoumnikova, 2000). However, a direct comparison of these studies is problematic because definitions of “creativity” vary wildly.

In the present study we examined creative performance in normal controls, schizophrenics, and psychometrically ascertained schizotypes using a novel DT task in order to: (1) test the association between enhanced creativity and schizotypy; and (2) elucidate the neural correlates of DT. We examined hemispheric prefrontal activation during creative thinking using near infrared spectroscopy (NIRS) in a subset of subjects from the behavioral experiment. We hypothesized that DT would be associated with greater bilateral PFC activity and that the schizotypes would show greater PFC activity during DT than other groups.

Section snippets

Subjects

Demographic information is presented in Table 1. 17 outpatient schizophrenic (SZ) subjects who met the DSM-IV criteria were recruited from a local clinic. 17 healthy control (CO) and 17 schizotypal (SCT) subjects were recruited from the community. Exclusion criteria included substance abuse, neurological disorders, and history of head trauma. All patients were taking atypical antipsychotic drugs and were clinically stable. There were no significant group differences in education, handedness, or

Results

RAT: For the number of correct responses on the RAT, there was a main effect of group (F(2, 48) = 4.03, p < 0.05; r = 0.39). Normal controls (M = 10.0, SD = 6.1) gave more correct responses than schizophrenics (M = 5.5, SD = 4.3) (p < 0.05).

DTT: We recorded the number of singular and combinatory uses. For each trial, single object “use” responses were summed. Combinatory responses were calculated for each trial by summing the number of responses that included a use for at least two objects within the stimulus

Discussion

The major findings of this study were that: (1) schizotypy is associated with enhanced DT; (2) DT is particularly associated with disorganized schizotypal traits; (3) DT is associated with bilateral PFC activity; and (4) Schizotypes, who have enhanced creative thinking ability, recruit the right PFC preferentially compared to SZ and CO.

To our knowledge, this is the first study to compare the functional neuroanatomy of DT in SCT, SZ and CO. Our data support evidence for enhanced DT in

Acknowledgments

We thank Crystal Gibson, Chris Cannistraci, Susan J. Hespos, John Gore, Gordon Claridge, Peter Brugger, Christine Mohr, and Lynn DeLisi. This work was supported in part by the Discovery Grant to S.P. and by an NIMH training grant (T32-MH18921) and NICHD Grant P30HD15052.

References (68)

  • L.A. Miller et al.

    Effects of focal brain lesions on visual problem-solving

    Neuropsychologia

    (1996)
  • M. Miran et al.

    Cerebral asymmetries: neuropsychological measurement and theoretical issues

    Biological Psychology

    (1984)
  • T.O. O'Reilly et al.

    Schizotypy and creativity: an evolutionary connection?

    Personality and Individual Differences

    (2001)
  • H. Petsche

    Approaches to verbal, visual and musical creativity by EEG coherence analysis

    International Journal of Psychophysiology

    (1996)
  • D. Rawlings et al.

    Using a ‘taboo response’ measure to examine the relationship between divergent thinking and psychoticism

    Personality and Individual Differences

    (1997)
  • O.M. Razoumnikova

    Functional organization of different brain areas during convergent and divergent thinking: an EEG investigation

    Brain Research Cognitive Brain Research

    (2000)
  • O.M. Razumnikova

    Gender differences in hemispheric organization during divergent thinking: an EEG investigation in human subjects

    Neuroscience Letters

    (2004)
  • A.J. Richardson

    Dyslexia, handedness and syndromes of psychosis-proneness

    International Journal of Psychophysiology

    (1994)
  • M. Rodel et al.

    Hemispheric dissociation in judging semantic relations: complimentarity for close and distant associates

    Brain and Language

    (1992)
  • J.P. Rushton

    Creativity, intelligence, and psychoticism

    Personality and Individual Differences

    (1990)
  • H. Sato et al.

    Practicality of wavelength selection to improve signal-to-noise ratio in near-infrared spectroscopy

    Neuroimage

    (2004)
  • S.C. Schachter et al.

    Associations of handedness with hair color and learning disabilities

    Neuropsychologia

    (1987)
  • J. Shaw et al.

    Schizotypy and shift from dextrality: a study of handedness in a large non-clinical sample

    Schizophrenia Research

    (2001)
  • M. Spitzer et al.

    Associative semantic network dysfunction in thought-disordered schizophrenic patients: direct evidence from indirect semantic priming

    Biological Psychiatry

    (1993)
  • S. Weinstein et al.

    Are creativity and schizotypy products of a right hemisphere bias?

    Brain and Cognition

    (2002)
  • J. Zanes et al.

    The relationship between creativity and psychosis-proneness

    Personality and Individual Differences

    (1998)
  • N.C. Andreasen

    Negative symptoms in schizophrenia. Definition and reliability

    Archives of General Psychiatry

    (1982)
  • N.C. Andreasen et al.

    Creativity and psychosis. An examination of conceptual style

    Archives of General Psychiatry

    (1975)
  • N.C. Andreasen et al.

    Negative v. positive schizophrenia. Definition and validation

    Archives of General Psychiatry

    (1982)
  • M. Bartlett et al.

    Do the Wallach and Kogan tests predict real creative behavior?

    Perceptual and Motor Skills

    (1974)
  • N.P. Bekhtereva et al.

    Study of the brain organization of creativity: II. Positron–emission tomography data

    Human Physiology

    (2000)
  • E.M. Bowden et al.

    Aha! Insight experience correlates with solution activation in the right hemisphere

    Psychonomic Bulletin & Review

    (2003)
  • G.M. Boynton et al.

    Linear systems analysis of functional magnetic resonance imaging in human v1

    Journal of Neuroscience

    (1996)
  • P. Brugger et al.

    ESP extrasensory perception or effect of subjective probability?

    Journal of Consciousness Studies

    (2003)
  • Cited by (176)

    • Human creativity: Functions, mechanisms, and social conditioning

      2024, Advances in Experimental Social Psychology
    View all citing articles on Scopus
    View full text