Response habituation in unconscious patients

Abstract

Reactivity and response habituation were studied in 42 unconscious patients. They were easily separable into six grades of unconsciousness by the types of stimuli they responded to. These grades were clinically describable as depth of unconsciousness. This provides a rapid technique by which even nonmedical personnel can classify unconscious patients. The four lightest grades responded to sound with a variety of responses; there was no typical pattern or gradation in the responses observed. However, all responses habituated in all patients, and only a few trials were required. The rate of habituation showed no significant relation to grade of unconsciousness. Sensitization was almost exclusively observed in the lightest grade. Savings from one day to the next were not related to grade of unconsciousness, but were positively related to prognosis.