Effects of self-induced mental imagery on autonomic reactivity in children

The purposes of this research study were: (1) to determine whether changes in cardiac rate, skin temperature, and/or electrodermal activity occur as children change mental imagery and (2) to determine whether such changes are related to age, sex, or other variables. Children who were evaluated in this study had no previous experience with hypnosis or biofeedback training and were in good health with no learning disabilities. Thirty-eight boys and 38 girls ranging in age from 5 to 15 years were studied in a comfortable setting with a constant room temperature and biofeedback equipment. A Procomp 5DX computer software unit was used to measure autonomic reactivity during baseline and mental processing periods. After baseline monitoring indicated stabilization of autonomic measures, each child was asked to think about being in a quiet, pleasant place for 120 seconds. Pulse rate, skin temperature, and electrodermal activity were recorded. A resting period followed, and each child was then asked to think about an exciting activity, such as a preferred sports activity, for another 120 seconds. At the end of this monitoring, each child was asked to describe what had been his/her mental imagery during the two monitoring periods. Data analysis used paired t tests and repeated measures analysis of variance. For all children, the pulse rates showed significant decreases (p < .001) during quiet and relaxing imagery and significant increases (p < .001) during active imagery. Skin temperatures increased significantly (p < .001) during quiet imagery and active imagery, whereas electrodermal activity decreased (p < .001) during active imagery. Observed changes did not relate to age or sex. The results confirm our clinical observations that deliberate changing of mental imagery by children results in immediate autonomic changes. Questions evolving from this study and similar studies done in adults are: (1) Do average-thinking processes impact on autonomic changes over long periods of time and (2) do these changes ultimately impact on health, such as cardiovascular status?