Schizotypy and hemisphere function—I : Theoretical considerations and the measurement of schizotypy

This paper brings together, in the context of individual-differences theory, two developing themes in schizophrenia research. One concerns the manifestation, in normal people, of ‘psychotic’ characteristics and their measurement using scales which, unlike the Eysenck P scale, draw their items from the clinical symptomatology of psychosis. Recent work on the so-called ‘borderline states’ is considered especially relevant and a new two-scale questionnaire (STQ) is described which was modelled on the current distinction, in DSM-III, between ‘schizotypal personality disorder’ and ‘borderline personality disorder’. The second theme addressed concerns the possible biological basis of individual differences in ‘schizotypy’. It is argued, in the light of some emerging views about the nature of schizophrenia, that this may lie in the functional and structural properties of hemisphere organization. A suggested strategy for evaluating this theory is an examination of the performance of schizotypal normal Ss on tests of hemisphere function.     

Development of differences in response latencies to right and left visual fields

Robust lateralization developed in right-handed adults who were asked to judge letter pairs as "same" or "different" during 4608 trials. By the end of the first two blocks (768 trials) "same" responses were favored when presented in the RVF (transmitted directly to the left hemisphere) and "different" responses were favored when presented in the LVF (transmitted direction to the right hemisphere). This gradually reversed over sessions with "same" responses becoming faster for letters presented in the LVF, and "different" responses becoming faster for stimuli presented in the RVF. The laterality acquired under these conditions was cumulative and reproducible, appeared in all 16 subjects, and was preserved between sessions a week apart. The data suggest that laterality is a flexible and reversible characteristic of the human brain even when stimulus and task remain constant.     

Representation of linear orders

Two binary classification tasks were used to explore the associative structure of linear orders. In Experiment 1, college students classified English letters as targets or nontargets, the targets being consecutive letters of the alphabet. The time to reject nontargets was a decreasing function of the distance from the target set, suggesting response interference mediated by automatic associations from the target to the nontarget letters. The way in which this interference effect depended on the placement of the boundaries between the target and nontarget sets revealed the relative strengths of individual interletter associations. In Experiment 2, students were assigned novel linear orders composed of letterlike symbols and asked to classify pairs of symbols as being adjacent or nonadjacent in the assigned sequence. Reaction time was found to be a joint function of the distance between any pair of symbols and the relative positions of those symbols within the sequence. The effects of both distance and position decreased systematically over 6 days of practice with a particular order, beginning at a level typical of unfamiliar orders and converging on a level characteristic of familiar orders such as letters and digits. These results provide an empirical unification of two previously disparate sets of findings in the literature on linear orders, those concerning familiar and unfamiliar orders, and the systematic transition between the two patterns of results suggests the gradual integration of a new associative structure.     

Cognitive dysfunction in compulsive checkers: Further explorations

Recent evidence suggests a relationship between certain memory deficits and compulsive-checking behavior. The present study explores this relationship in the context of several additional memory capacities not yet investigated. Using the Maudsley Obsessional-Compulsive Inventory and the Everyday Checking Behavior Scale four groups of Ss were identified: (1) frequent checkers, (2) occasional checkers, (3) infrequent checkers and (4) noncheckers. Consistent with previous research, a memory-for-actions task indicated a deficit among compulsive checkers. Furthermore, checking status was found to be negatively related to memory functioning as measured by the Wechsler Memory Scale (WMS) and the Cognitive Failures Questionnaire (CFQ). This memory deficit was most pronounced on the Logical Memory subtest of the WMS. Checkers appear to have difficulty recalling details of meaningfully linked sequences, either presented in narrative form or engaged in personally. Although the reasons for these checking-related deficits are not clear, a complete understanding of checking phenomena will involve an appreciation of the role played by memory deficits.     

Abnormal and normal obsessions—A replication

A replication of previous work on the incidence and characteristics of intrusive cognitions in non-clinical populations was carried out. The results closely reflected those obtained previously, and further relationships between variables were found. The importance of distinguishing between- and within-S data is stressed.     

THE IMPACT OF PSYCHOLOGICAL TESTING ON EDUCATIONAL AND PERSONNEL SELECTION IN AFRICA

Psychological testing for Education and Personnel selection is of great importance in the efforts by many African countries to ensure that suitable candidates are selected for education beyond the primary school level and for training for different employment. Major investigations directed to this need have been in the area of adapting tests already available in Western countries and determining the reliability and predictive validity of battery of tests so adapted and their tryout in African schools to determine their efficiency as tools for selection.     

Stress, externality, and depression

Previous research has found mixed support for the possibility that locus of control moderates the effects of life stress on depression. Two methodological choices may have influenced previous findings: the use of a unidimensional rather than a multidimensional locus of control scale, and reliance on linear statistical methods using median splits. We attempted to correct these choices by using the Levenson IPC scale (1974) and multiple regression analyses in a female undergraduate population (N = 158). The results supported use of a multidimensional scale, since Stress, Internality, and Powerful Others were found to have main effects on depression whereas Chance interacted with life stress. The question of whether locus of control refers to responsibility for causing an event, i.e., self-blame, or belief in control over future events, i.e., coping behavior, was discussed.     

Sex differences in problems related to depression

The study investigated possible sex differences in the types of problems that are correlated with Beck Depression Inventory (BDI) scores, using a sample of college students. Problems related to assertiveness and feeling ill at ease were positively correlated with BDI scores for males, but not for females. In contrast, conflicts with parents, feelings of being boxed in and of boredom, lack of money, and chronic physical complaints were positively related to BDI scores for females, but not for males.