The Effect of Verbal Stress on Salivary Outflow, Heart Rate, and Vasomotor Activity

Abstract

The effect of verbal stress on physiological indices and its relationship to the level of anxiety (MAS) and of experimentally induced tension (EIT) was tested on 100 Ss. When the stressor was given, EIT was found to be related significantly to the amount of change in salivary outflow (inhibition) and volume pulse amplitude (inhibition), while MAS failed to exhibit any significant relationship to the changes in physiological responding. Sex differences were not found in any of these indices. Several discrepancies in results between the present study and other such investigations were discussed. Kotake (1943) in his study of conditioned salivary reflex in humans reported that CR was well established when the S adapted to the experimental situation. This finding may well be explained in terms of Pavlov's external inhibition which grows out of unfamiliar experimental surroundings.In such alimentary conditioning, the inhibitory or disturbing effect of the experimental situation will be minimized by giving the S a sufficient period of time to adapt to the situation. However, one of the difficulties with which most of the investigators of aversive conditioning in humans meet is that the E's instruction on pain-to-come has itself a fairly effective influence upon the S's physiological activities. Before starting aversive conditioning, the E would give the instruction to the S, informing him that an electric shock or an air-puff will be applied in the experiment. This communication to the S allows him to fall into a state of high anxiety resulting from the S's expectation of a painful stimulus. The reactions we observe and measure under the condition as such, have a considerably sensitized level of reactivity than those obtained under a resting condition.Complete adaptation, in a true sense, to the instruction of pain-to-come may almost never be expected in this type of experiment.If the instruction of pain-to-come is not given to the S, the matter will become much worse, because the S will lie on a bed with a variety of expectations as to the future of the experiment; some are relaxed and others fearful, as shown in the author's previous study (Miyata, 1961). Therefore, to keep the S's attitude homogeneous at the start of the aversive experiment, instruction to the S is not to be omitted.Thus, the S's " fearfulness-in-the-experimental-situation," if we may be allowed to use Kamin's term (1955), motivated the present study to see how the stress verbally induced during the experiment affects physiological reactions such as salivary outflow, heart rate, and vasomotor activity. And also investigated was the extent to which the physiological changes appearing under the stress are related to the level of experimentally induced tension (EIT), or of anxiety scaled by a manifestanxiety test (MAS).