A Study of Conditioned Vasomotor Responses in Ten Human Subjects*

Abstract

The purpose of this study, which was begun under the direction of Dr. Felix Deutsch and Dr. Carlyle F. Jacobsen, was as follows: to demonstrate that positive conditioned vasomotor responses can be established in the human subject; to compare the objective data obtained during conditioning with introspective material obtained at the same time; and to determine whether there is any relationship between vasomotor imbalance and degree of vasomotor conditioning. The measurements were done with a photoelectric plethysmograph which measures the light that scatters in the skin. The unconditioned stimulus was a faradic current, produced by an inductorium and applied through electrodes fastened to opposite sides of the right wrist by a leather strap. The conditioned stimulus was visual. It was produced by a 2.2 volt flashlight bulb supplied by a 2 volt wet cell and fastened to the wall at the end of a couch on which the subject lay so that the light was in his line of vision. The presentation of stimuli was rigidly controlled by a specially constructed timing device made from a multi-speed electric kymograph. Measurements of the photographed tracings before and after stimulation were made, and the differences were converted into filter units which allowed quantitative comparisons of records taken on different subjects. The total vol. change, the pulse vol. change and the latent period of reaction were measured. The plethysmograms taken during this period, and all subsequent ones, were analyzed for respiratory waves, 3d order waves, and any irregularities that might be present. The results indicate that subjects who show signs and symptoms of autonomic imbalance tend to become more easily conditioned. Once obtained, this conditioned response appeared to be relatively stable. Conditioning and extinction curves of this type of conditioning did not always follow the typical curves of learning and forgetting. The irregularity of the curves may be attributed to: the instability of the unconditioned responses in some subjects; changes in attitude and emotional set of the subject; and other factors not studied in this expt. Subjects who were relatively easily conditioned showed more rapid and complete elimination of incidental vascular reflexes to the light stimulus, and showed a tendency toward more stable conditioned responses during extinction than subjects who were not easily conditioned.