Expectancy and type of activity: effects on pre-stress cardiovascular adaptation

This study evaluated the effects of expectancy and type of activity on cardiovascular change during a 20 min pre-stress adaptation period. Subjects (N = 115) were randomly assigned to six conditions with three differing types of activity and two different instructions for expectancies. The three activities were (a) resting quietly, (b) reading neutral, entertaining material (i.e., Herman cartoons), or (c) reading stress-relevant questionnaires. Subjects were told to either expect or not expect to participate in a subsequent stress study. The findings clearly indicated that (1) neither the expectancy nor the activity manipulations had significant impact on autonomic resting values at the end of 20 min of adaptation, but (2) subjects consistently reported increased feelings of relaxation and noted differential mood change in the cartoon relative to the stress questionnaire condition. Furthermore, the study revealed that instructions to read stress questionnaires initially delayed heart rate adaptation when contrasted with the resting and cartoon conditions. Implications of these findings for a more comprehensive understanding of the pre-stress adaptation phenomenon are discussed.