In order to determine ways in which disabled and non-disabled people react to low levels of stress, the reliability of heart and respiratory measures under different conditions was studied. Eighty-five subjects (paraplegics, cardiacs, and physically normal controls) were given a variety of tests with the following results: over a 1-week interval the physiological measures were less reliable than most psychometric paper and pencil measures; respiration was more reliable than cardiac measures; and the more dynamic the stimulus situation, the lower the reliability of the physiological measure. No consistent patterns of a relationship between physiological measures and the relatively more static paper and pencil tests was found. Indications were that under low levels of stress the patients in different disability categories seemed to show differential responses in the disability affected areas. (Author/RJ)