Experimental psychogenic hypertension: blood pressure changes conditioned to painful stimuli (schizokinesis).

1. During habituation in 4 dogs to a new environment and attachment of apparatus, the blood pressure was at first high but fell from about 175 systolic the first day to about 135 on the ninth day. 2. In the first group of dogs used two years previously to form 3 cardiac conditional reflexes to 3 intensities of shock, the blood pressure measured after a 13-month rest was retained and specific to the 3 intensities of shock. In another group of 2 dogs the blood pressure was specific to the excitatory and to the inhibitory signals for pain. 3. The conditioned hypertension was parallel to the conditioned heart rate. 4. The conditioned hypertension was parallel to the motor conditional reflex with certain exceptions: the conditioned hypertension was, like the cardiac conditional reflex, quicker to form and more persistent, thus being present often in the absence of the motor conditional reflex--an evidence of schizokinesis. 5. The conditioned hypertension was retained for a 13-month rest period without intervening training, being present immediately when the dog was brought back into the environment where the stress had been given. 6. Although the conditioned hypertension was retained in the long rest period, it could in one dog be reduced somewhat by repeating the conditional stimulus without the shock (non-reinforcement), a more efficient way of extinction than simple rest. In another dog the hypertension became exaggerated though there was no repetition of the stress, showing evidence of an internal development (autokinesis). 7. The amplitude of the conditioned hypertension varied according to the individual dog from about 130 average control to limits of 150 to 225 (conditioned hypertension) in the separate dogs.