Loose but normal: a semantic association study

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

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.

Association of schizotypy with semantic processing differences: an event-related brain potential study

Disorganized speech in both schizophrenia and schizotypy has been hypothesized to result from abnormalities in how concepts activate one another in semantic memory. To study whether schizotypy is associated with differences in how categories activate their exemplars, we examined the N400 component of the event-related brain potential (ERP) elicited during a category-verification task. ERPs were recorded in young adults from the general population while they viewed category definitions each followed by a target that was either a high-typicality exemplar, low-typicality exemplar, or non-exemplar; participants' task was to indicate whether or not the target belonged to the category. Schizotypy was assessed via the Schizotypal Personality Questionnaire (SPQ). Overall, N400 amplitude was largest for non-exemplars, smallest for high-typicality exemplars, and intermediate for low-typicality exemplars. SPQ score was associated with decreased N400 amplitude to non-exemplars, and increased amplitude to both types of exemplars. SPQ score was negatively correlated with the N400 amplitude difference between non-exemplars and both low- and high-typicality exemplars, but was not correlated with the amplitude difference between low- and high-typicality exemplars. N400 amplitude differences between non-exemplars and both types of exemplars were correlated with the SPQ Interpersonal factor, but not the Disorganized factor. The results are consistent with an association of schizotypy with decreased use of context to activate related items and inhibit unrelated items.

Magical food and health beliefs: a portrait of believers and functions of the beliefs

The aims of the present two studies were to delineate a portrait of people who are attracted to magical beliefs about food and health and to study the self-reported functions for the beliefs. Participants were Finnish men and women ranging in age from 15 to 66 years (N=3261 in study 1 and N=189 in study 2), and they filled in either an Internet-based or a paper questionnaire. The believers were more often women than men, vegetarians than omnivores, and they relied more on alternative medicine, thought in a more intuitive way, and demonstrated more eating-disordered thinking than the nonbelievers. Additionally, the believers had experienced slightly more negative life events than the nonbelievers in study 1 but contrary to our hypothesis, they did not differ in their desire for control. The believers reported value-expressive function as the most important one served by their beliefs, followed by the control and utilitarian functions. The emotional, intuitive nature of food beliefs and their connection to values and identity are discussed.

Recognition of metaphor and irony in young adults: the impact of schizotypal personality traits

Patients with schizophrenia demonstrate two dissociable impairments of pragmatic language comprehension: (1) an insensitivity to irony, which is associated with poor theory-of-mind (i.e. a difficulty with inferring other people's thoughts); and (2) poor recognition of metaphors, which may reflect degraded semantics. This study investigated whether non-clinical high-schizotypal adults show similar impairments of pragmatic language. Thirty-six university students completed the Raine Schizotypal Personality Questionnaire, the Wechsler Memory Scale Logical-Memories subtest, Raven's Progressive Matrices and a story comprehension task that tested the ability to discriminate between incongruous statements and appropriate uses of ironical, metaphorical or literal speech. Counter to the pattern found for patients, high-schizotypal adults were just as capable as low-schizotypal adults of identifying appropriate metaphors, suggesting a discontinuity between schizophrenia and schizotypy for the metaphor-recognition problem. This study's finding of intact metaphor recognition in high-schizotypal adults contrasts with previous findings of poor proverb comprehension in these individuals and is interpreted in terms of different semantic processes required for recognizing and interpreting metaphors. Consistent with the pattern found for patients, high-schizotypal adults were significantly impaired in their ability to appreciate when a literally contradictory utterance could be interpreted as ironical, suggesting continuity between schizophrenia and schizotypy for the irony-appreciation problem.

Deviant olfactory experiences, magical ideation, and olfactory sensitivity: a study with healthy German and Japanese subjects

Little is known about the relationship between olfactory hallucinations and olfactory sensitivity in psychiatric populations. However, in healthy subjects, a 'psychotic-like' feature, namely magical ideation, has been linked to deviant olfactory experiences. We thus assessed olfactory sensitivity, magical ideation and deviant olfactory experiences in 42 healthy subjects (21 Germans and 21 age- and gender-matched Japanese). The results show that: (1) Germans had significantly higher magical ideation scores and a higher frequency of deviant olfactory experiences than Japanese, and more Germans than Japanese reported having had deviant olfactory experiences at least once in their lives; (2) in Germans, the occurrence of deviant olfactory experiences was correlated with higher magical ideation scores; and (3) there was no relationship between olfactory sensitivity (olfactory thresholds) and either deviant olfactory experiences or magical ideation, respectively. We conclude that: (1) the lack of deviant olfactory experiences in Japanese may best be explained by cultural differences in the response attitude towards questionnaires requiring self-disclosure; (2) the positive relationship between magical ideation and deviant olfactory experiences strengthens the supposed link between 'psychotic-like' features in healthy populations and real hallucinations of psychiatric patients; and (3) the absence of a relationship between olfactory sensitivity and deviant olfactory experiences suggests that their anatomical-functional correlates within temporo-limbic regions may differ.