Abstract
The author presents an evidence-based psychological theory which is derived from clinical observations, a review of the literature, especially the split-brain literature, and experimentation with lateral visual field stimulation which has been found to induce changes in patients' cognitive and emotional status thought to be associated with the relative activation of one cerebral hemisphere or the other. The evidence from lateral visual field stimulation suggests that often each hemisphere can have distinct psychological perspectives differing especially in their level of neuroticism with one visual field evoking a more immature perspective than the other. One of the central tenets of the hypothesis is that psychological traumas are associated more with one cerebral hemisphere and than the other, and that the ultimate aim of psychiatric care then becomes the teaching of the mental entity associated with this troubled hemisphere that it is now safer and more valued than it had been at the time of the trauma.