A mathematical theory of the affective psychoses

The theory introduces two variables ϕ and ψ. The first represents the intensity of emotion, the second measures the intensity of activity. A set of integrodifferential equations is assumed to govern the variation of ϕ and ψ with respect to time. Since for increasing values of ϕ the conduct of the organism varies from great impassivity through a normal level of feeling to extremes of a circular depression or catatonic excitement; whereas an increase of ψ results in a transition from stupor to manic excitement, the solutions of the equations represent quatitative specifications of different psychotic states.