published_or_final_version / Psychiatry / Doctoral / Doctor of Philosophy

Schizotypal Cognitions (RISC) were related to interview derived ratings of DSM-III-R schizotypal personality disorder and other personality disorders in a non-clinical college sample was examined. Moderate correlations between the RISC and schizotypal scores, but not between the RISC and other personality disorders, provided support for the validity and suggested reasonable specificity for the instrument. RISC scores correlated the greatest with schizotypal symptoms that reflect a strong cognitive component (e.g., perceptual illusions) but did not correlate with symptoms associated with social adaptation or interpersonal functioning (e.g., excessive social anxiety). Cutoff scores set at approximately 2 S.D. above the RISC mean best discriminated between non-cases and cases of subthreshold and definite schizotypal personality disorder. Limitations of the RISC and suggestions for future research are discussed. / Department of Psychological Science

The object of this study was to investigate the adequacy of a test battery for the differential diagnosis of early schizophrenia. A test battery consisting of a physiological test of autonomic nervous system reactivity, psychological tests of abstract-concrete attitude and the Sc (schizophrenia) scale of the Minnesota Multiphasic Personality Inventory was administered to an experimental group of 50 early schizophrenics and a control group of 50 patients suffering a functional disorder other than schizophrenia. Each subject of both groups was on his (her) first admission to a psychiatric institution. The groups were matched on the basis of age, sex and IQ. The test battery was found to statistically differentiate the two groups at the 2 per cent level and beyond, indicating that the test battery is adequate for differential diagnosis of early schizophrenia. No relationship was established for the expected correlation between autonomic nervous system hyporeactivity, impairment on tests of abstract-concrete attitude and an abnormal trend in the schizoid direction as measured by the Sc scale of the MMPI. It had been suggested that associative and affective functions in schizophrenia are impaired in a related fashion. The hypothesis that combination of loss of abstraction ability, schizoid personality trend and physiological phenomenon interpreted as "release" of the autonomic nervous system from higher (cortical) control was not confirmed. / Arts, Faculty of / Psychology, Department of / Graduate

published_or_final_version / abstract / Psychiatry / Master / Master of Philosophy

The present study investigated early visual information processing of individuals whose Minnesota Mutiphasic Personality Inventory (MMPI-168) profiles indicated schizophrenic tendencies in the absence of an obvious thought disorder. These schizotypic individuals were identified by the 2-7-8 M PI code type and were compared on a visual backward masking task with three other groups: an "Inflation-free" group, an "Other-inflations" group, and a group with an "8-9" MMPI code. The 2-7-8 and the 8-9 groups had significantly fewer correct identifications of target stimuli than either the Inflation-free group or the Other-inflations group. The 2-7-8 group had significantly higher Critical Stimulus Durations (CSD) than either the Inflation-free group or the 8-9 group. These results suggest that both the 2-7-8 group and the 8-9 group are more vulnerable to the effects of the masking stimulus. Schizophrenics have demonstrated similar susceptibility to masking stimuli. It is suggested that both the 2-7-8 and the 8-9 M I profile code may be an index of vulnerability to schizophrenia.

It has been proposed that delusional thinking 'may be on a continuum with, normal behaviour and can be assessed by taking account of, factors such as the client's degree, of belief conviction or the extent of preoccupation with the belief. In the present research a number of -measures were employed to assess theý delusional thinking of people diagnosed as schizophrenic. - Two -interventions were eipployed: (i) a structured verbal challenge, and (ii) a reality test in which the belief was subject to an empirical test. The research offered support for the continuum view of delusional behaviour, and demonstrated that a number of aspects of delusional behaviour, including the degree of conviction with which the belief is held, are open to modification.

The relationships between lateral ventricle size, smooth pursuit eye tracking, and neuropsychological test performance were investigated using a sample of 30 chronic schizophrenic inpatients. There were no significant correlations between any of the measures. Compared to a control group of normal volunteers, the schizophrenic patients showed abnormally poor eye tracking accuracy but did not show lateral ventricular enlargement. Compared to a group of age matched non-schizophrenic psychiatric patients, the schizophrenic patients were impaired on six out of ten neuropsychological tests. As there was no evidence of lateral ventricle enlargement, it is clear that eye tracking impairment and deficits on neuropsychological tests may occur independently of enlarged lateral ventricles. The absence of relationships between impairments on the neuropsychological tests and poor eye tracking is not thought to be the result of restricted performance ranges for any of the measures. The most parsimonious conclusion is that there is no relationship between eye tracking and the variety of neuropsychological functions assessed in this study. However, an alternative possibility is that the study sample was too homogeneously impaired, and a relationship between eye tracking impairment and neuropsychological deficits might emerge in a more diverse sample representative of the range of individuals currently diagnosed as schizophrenic. / Arts, Faculty of / Psychology, Department of / Graduate

The present study employed the Rust Inventory of Schizotypal Cognitions (RISC) to identify an experimental group of schizotypics (as well as an appropriate control group). It was hypothesized that these individuals would show patterns on a battery of neuropsychological tests (e.g., Category Test, Tactual Performance Test, and Trails B from the Halstead-Reitan Neuropsychological Battery; Expressive Speech, Memory, and Intellectual Processes Scales from the Luria-Nebraska Neuropsychological Batter; and the Rey Complex Figure Test) similar to those exhibited by actual schizophrenics. Findings indicated that schizotypes do show a pattern of deficits on neuropsychological tests similar to those observed in diagnosed schizophrenics. These results lend validity to the RISC as an instrument for use in selecting those at-risk for schizophrenia. They also illustrate a possible neuropsychological vulnerability marker for schizophrenia. / Department of Psychological Science

Within the past decade the field of clinical psychology has become increasingly concerned with projective tests as a means of facilitating the understanding of the dynamic makeup of the individual personality. The enthusiasm over these techniques has resulted in the development of a barrage of projective techniques, purporting to uncover dynamics and "complexes" to a sometimes fantastic and often dubious extent. The subjective nature of these tests appears to render them most difficult to quantify and validate experimentally. Although the Mosaic test dates its origin twenty-five years back, there have been few, if any, successful validation studies. Those that have been attempted, have been poorly executed and their results inconclusive, or incongruous with other findings. The bulk of the literature on the test seems to consist of enthusiastic affirmation and ways and means of interpretation but little objective data to substantiate the findings. The test is considered by many to be most successful in its sensitivity to various entities of psychiatric diagnosis. That is, the mosaic design of psychotics, narcotics, and "normal" individuals, etc., are alleged to fall into distinct types. Those who a:re confident in this have offered certain criteria as indicative of mosaics of these various clinical groupings. The purpose of this study is to determine how successfully mosaic patterns constructed by persons with psychiatric diagnoses of schizophrenia can be differentiated from those constructed by non-schizophrenic (i.e., "normal'') individuals, and which criteria are found to be most valid in making such a distinction.

published_or_final_version / abstract / Psychiatry / Master / Master of Philosophy