Diverging neuropsychological models of hemispheric dysfunction in schizophrenia and depression as well as the moderating role of emotion on the onset and course of these disorders are the subject of investigation of this study. Deficits in patients with acute schizophrenic psychosis have usually been interpreted as indicating primarily left hemispheric dysfunction (Flor-Henry 1969, Gur 1978, Magaro & Chamrad 1983, DeLisi et al. 1989). This view has been challenged by some authors who have suggested a primary deficit in the right hemisphere (Schweitzer 1982, Venables 1984, Oepen et al. 1987, Cutting 1990), or dysfunction involving both hemispheres (Kolb & Whishaw 1983, Gruzelier 1984, Taylor 1984). Quite apart from any brain pathology, family studies of schizophrenia have demonstrated that patients who live in families with high levels of expressed emotionality have a greater risk of relapse than patients living in other families (Brown et al. 1972; Leff & Vaughn 1976). This finding emphasizes the importance of psychosocial factors on the course of schizophrenic illness.