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Visual illusions are popularly referred to as the phenomena where the eye sees something that is not there. The aim of this review is to show that illusions are not the occasional misinterpretations of the physical world. Illusions are critical to our understanding of perceptual processes. The cause of illusions can vary depending on the reflection or refraction of light, how the brain processes the information reaching the retina, or how the visual system works when perceiving depth. Illusions, which have inspired both artists and scientists, have been instrumental in our understanding of human perception and the functioning of the brain in general. At the beginning of this article, the classes that emerge from a scientific perspective will be defined in parallel with the hierarchical visual perception. Examples of illusions that inform us about the physiological (corresponding to the early stages of visual perception) processes and cognitive (corresponding to higher level stages of visual perception) strategies will be given, and the factors that may cause them will be examined. In the light of theoretical approaches and perceptual grouping concepts, I will discuss how these interpretations help us to understand the brain and human nature. Next, I will give examples of findings and applications in clinical populations to touch on the role of illusions in our understanding of visual perception in e.g. schizophrenia patients. [ABSTRACT FROM AUTHOR]

Schizophrenia is a disorder that consists of positive, negative symptoms, cognitive impairment, disorganization and various dimensions and manifested as several clinical appearances because of different intersections of these dimensions at different levels. The description of the schizophrenia-like clinical picture is based primarily on the finding that psychosis-like symptoms have accumulated in families of patients with schizophrenia. The following studies have examined paranoid, schizoid and schizotypal personality disorders in this spectrum by comparing them to schizophrenia. The idea intensely becomes more dominant in the literature that especially schizotypal personality disorder (SPD) is a non-progressive schizophrenia spectrum disorder in which different dimensions of schizotypy are seen together rather than a personality disorder. Among the personality disorders, SPD has the strongest genetic relationship with schizophrenia. The term schizotypy was first described as a schizophrenia-like psychosis phenotype. To date, studies have shown schizotypy has different dimensions, such as schizophrenia, and that reflections of these dimensions are common in non-clinical populations and individuals at risk for psychosis. At the same time, several studies found related dimensions of schizophrenia and schizotypy have similar neurobiological bases. As per the definiton of prodrome is a condition can only be defined retrospectively in patients with schizophrenia. Therefore, schizotypal personality disorder and high schizotypy are predisposition indicators within the spectrum rather than reflecting the schizophrenia prodrome. Identifying of these borderline cases is important for uncovering etiopathogenesis of psychosis, early diagnosis of schizophrenia, intervention to predisposing factors and prevention of psychotic break.

Schizophrenia is a disorder that consists of positive, negative symptoms, cognitive impairment, disorganization and various dimensions and manifested as several clinical appearances because of different intersections of these dimensions at different levels. The description of the schizophrenia-like clinical picture is based primarily on the finding that psychosis-like symptoms have accumulated in families of patients with schizophrenia. The following studies have examined paranoid, schizoid and schizotypal personality disorders in this spectrum by comparing them to schizophrenia. The idea intensely becomes more dominant in the literature that especially schizotypal personality disorder (SPD) is a non-progressive schizophrenia spectrum disorder in which different dimensions of schizotypy are seen together rather than a personality disorder. Among the personality disorders, SPD has the strongest genetic relationship with schizophrenia. The term schizotypy was first described as a schizophrenia-like psychosis phenotype. To date, studies have shown schizotypy has different dimensions, such as schizophrenia, and that reflections of these dimensions are common in non-clinical populations and individuals at risk for psychosis. At the same time, several studies found related dimensions of schizophrenia and schizotypy have similar neurobiological bases. As per the definiton of prodrome is a condition can only be defined retrospectively in patients with schizophrenia. Therefore, schizotypal personality disorder and high schizotypy are predisposition indicators within the spectrum rather than reflecting the schizophrenia prodrome. Identifying of these borderline cases is important for uncovering etiopathogenesis of psychosis, early diagnosis of schizophrenia, intervention to predisposing factors and prevention of psychotic break. [ABSTRACT FROM AUTHOR]

Objective: Perceptual aberration is an important dimension of schizotypy which has been considered as a clinical determinant of psychosis proneness. The present study aimed to explore the validity and the reliability of the Turkish version of the Perceptual Aberration Scale. Methods: Internal consistency of the Perceptual Aberration Scale was studied in 222 university students and for test-retest reliability, the scale was readministered to 105 students. Convergent validity of the scale was measured by the Magical Ideation Scale in 128 students. Results: The internal consistency of the scale was Cronbach's alpha=0.90 and the test-retest reliability was r=0.59. The convergent validity of the scale was established by a significant correlation between the scores of the Magical Ideation Scale and the Perceptual Aberration Scale. Discussion: The Turkish version of the Perceptual Aberration Scale is a reliable instrument, which can be used to quantify the important dimension of schizotypy in university students. The scale should be validated in community-based samples and also the predictive validity of the scale should be investigated. [ABSTRACT FROM AUTHOR]

Objective: The patients with schizotypal personality disorder and many nonaffected relatives of patients with schizophrenia shares many neurophysiological, neurocognitive and neuroanatomic features of schizophrenia. The concept of schizotypy is useful to investigate the characteristics of liability for schizophrenia. Schizotypy has several distinct dimensions similar to schizophrenia. There is an impact of gender on schizotypal features. This study investigates the psychometric characteristics of Turkish version of Schizotypal Personality Questionnaire (SPQ). Method: The sample of the study consists of 388 medical students. The internal consistency and %10 cut-off scores were studied. Seventy-one students were readministered the scale to measure the test-retest reliability. The Magical Ideation Scale (MIS) was also administered to 86 students besides SPQ with the aim of testing concurrent validity. The factor structure of the scale was also examined. Results: The mean score of the scale was 25.9 and 10% high cut-off score was 42. The Crohnbach alpha coefficient of the scale was 0.91, the Cronbach coefficients for the subscales ranged from 0.66 to 0.83. Test-retest scores were highly correlated (r=0.84). The correlation coefficients of MIS with total score of SPQ and cognitive perceptual schizotypy score were 0.49 and 0.74 respectively. Males had significantly higher scores on the interpersonal schizotypy subscale. Factor analysis of the items and subscales supported the construct validity of the scale. Conclusions: SPQ is a reliable and valid instrument for studying several dimensions of schizotypy in young adults. [ABSTRACT FROM AUTHOR]