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This study reports evidence that schizophrenia patients are significantly impaired in both spatial and object (shape) working memory. A 3-s delay between exposure and recall of targets was used and Bayesian item-response theory was applied to compensate for the tasks' differential difficulty while simultaneously taking account of missing data from participant attrition. Weaker evidence was found that in schizophrenia both domains are equally impaired on average, that spatial and object working memory appear to be more highly correlated with each other in the schizophrenia population than in the normal population, and that schizophrenia patients show greater variability in spatial than object working memory performance.

Schizophrenia patients have difficulty processing nonliteral forms of discourse such as idiomatic expressions. We hypothesized that schizophrenia patients would show impaired idiom processing for literally plausible idioms (e.g., kick the bucket) but not for literally implausible idioms (e.g., be on cloud nine). Thirty-two patients and 36 controls listened to sentences containing literally plausible and implausible idioms and made lexical decisions about idiom-related or literal-related targets. Schizophrenia patients showed reduced priming for literally plausible idioms but intact priming for literally implausible idioms compared with controls. Both groups showed evidence of literal word priming. These results are consistent with the notion that schizophrenia patients make normal use of context under conditions that minimize the need for controlled processing.

The prevalence of eye-tracking dysfunction (ETD) is significantly elevated in individuals with a diagnosis of schizophrenia and in their nonschizophrenic relatives, suggesting that ETD marks a familial (most likely genetic) risk factor for schizophrenia. Birth in a season with intemperate weather is also a widely reported risk factor for schizophrenia and is particularly marked for the subgroup with no family history of the disorder. This study examined how these two risk factors covaried in 78 patients with a Diagnostic and Statistical Manual of Mental Disorders (3rd ed., rev.; American Psychiatric Association, 1987) diagnosis of schizophrenia. Eye tracking and birth-month weather were independently assessed. As hypothesized, patients without ETD were significantly more likely to be born in months with intemperate weather (both hot and cold) than either patients with ETD or people in the general population. Etiologic factors associated with severe weather near birth may be important sources of nonfamilial schizophrenia.

In 2 experiments, the authors investigated perceptual organization in schizophrenia to determine whether patients with schizophrenia used the Gestalt principles. In the visual embedded figures task (Experiment 1), the authors examined the principles of proximity and collinearity, whereas in the similarity task (Experiment 2), the authors examined similarity. Forty-three people participated in the study: patients diagnosed with schizophrenia (14) or with bipolar disorder (15), and 'normal' participants (14). All 3 groups of participants showed performance superiority in the condition that was facilitated by the use of the Gestalt principles in both tasks. This study supports the hypothesis that visual perceptual organization, in terms of utilizing the Gestalt principles, is relatively intact in people with schizophrenia.

Empirical links between schizophrenia and schizotypic psychopathology were examined. The Perceptual Aberration Scale (PerAb; L. J. Chapman, J. O. Chapman, & M. L. Raulin, 1978) was used to identify putative schizotypic individuals and a contrast group of nonschizotypic controls. The Thought Disorder Index (TDI; M. J. Coleman et al., 1993) was used to quantify and classify thought disorder in these individuals. High PerAb participants, selected for having an increased number of self-reported perceptual and body image aberrations, showed an elevation in the amount and frequency of thought disorder as well as an increased number of idiosyncratic verbalizations. This supports the hypothesis that psychometrically identified schizotypic individuals display thought disorder similar to that shown by schizophrenic patients and some of their 1st-degree relatives, suggesting that there is a relation between schizotypic psychopathology, as tapped by the PerAb scale, and clinical schizophrenia.

Most of us engaged in mental health research and services have been astounded by the extraordinary advances in the basic sciences, particularly in the life sciences, during the past 50 years, which is a mere instant in the span of the recorded history of science. We have witnessed the following, among many others: * The discovery in 1944 by Seymour Kety (Kety and Schmidt 1945, 1948) of a method to measure precisely the circulation of the blood in the brain, which permitted the measurement of a metabolic activity of the brain while performing various behavioral tasks, as is now being done with positron emission tomography (PET). * The introduction of the phenothiazines into the treatment of psychosis, which led to the intensive study of neural receptor and transmitter dynamics in major mental illnesses and the role these receptors and transmitters play in behavior (Deniker 1970; Laborit et al. 1952). * Watson and Crick's (1953) discovery of the double helix structure of DNA, which led to a revolution in molecular biology and made possible the discovery of the genetic etiology of many diseases, including some severe mental diseases. * The continued but increasingly sophisticated study of brain anatomical mapping and localization, aided by new electronic and computer techniques. * And I add to this list the precise measurement of cognitive processes and the ability to partition mental functions like attention into finer units (cf. Posner 1978).

The Wisconsin Card Sorting Test was administered to normal subjects assessed for schizotypy to evaluate their spatial working memory function. Results revealed that subjects with high perceptual aberration (PerAb) were less accurate in performing the delayed-response task compared to low PerAb subjects. In addition, high PerAb individuals were more likely to fail to maintain set on the task compared to low PerAb subjects.

Saccadic and smooth pursuit eye movements were recorded in three groups of subjects: a schizophrenic group, a non-schizophrenic psychotic patient comparison group, and a normal control group. Schizophrenic subjects demonstrated a greater decrease in saccadic response time than did normal controls in a gap task (when the fixation point was turned off 150 msec before the target appeared). The psychiatric comparison subjects did not differ from normal controls. Further, only schizophrenic subjects demonstrated a relation between smooth pursuit and saccadic eye movement performance, such that subjects with impaired smooth pursuit showed a larger decrease in saccadic response time in the gap task. The relation between performance on the gap task and quality of smooth pursuit and its relevance for a prefrontal deficit hypothesis of schizophrenia are discussed.