The issue of mental state variability is central to the understanding of psychiatric pathology in general and schizophrenia in particular. Historically, psychiatry has been interested in these phenomena. Kahlbaum (1863), Kraepelin (1896) and Bleuler (1911) about a century ago, richly described the symptoms and course of schizophrenia. Since then, theorizing and studies of schizophrenia have been varied and many, but currently researchers tend to avoid phenomenological descriptions. Only a small group has investigated the actual course, changes, stages and fluctuations in schizophrenia (Strauss et al., 1985). Even less is known about fluctuations of symptoms, mood, thought and behavior in real-life situations, although these issues are the bread and butter concerns of clinical psychiatry.

Currently biological formulations receive much attention in schizophrenia research. Most studies emerging from prominent institutes use new diagnostic techniques such as MRI, PET scans, and CBF that promise to bring to fruition the search for functional and anatomical abnormalities in schizophrenia. Epidemiological researchers ponder issues such as cross-national prevalence differences and unequally distributed birth rate frequencies over the months of the year, of persons developing schizophrenia later in life. Psychological scholars focus on intellectual and cognitive factors such as loss of abstracting ability, perception and attention difficulties, and problems with faulty associations and thinking, all of which are tied to slow learning and adaptive liability (Rabin et al., 1979). These studies have enhanced our knowledge of schizophrenic symptomatology.