The author feels that the failure of extensive experimentation in the field of sensory deprivation to provide more conclusive answers lies in the inadequate recognition of the complexity of the variables that enter into the situation of sensory restriction. The article attempts to classify some of these variables and assess their importance—factors such as the extent of deprivation, the sense organ deprived (visual, auditory, tactile), duration, and interpersonal isolation. The problem of evaluating the output and the behavioral signs that emerge from sensory deprivation is discussed.