Palmar Sweat Index: A sensitive indicator of autonomic reactivity in experimentally induced stress

This study investigated the influence of activation on the number of active sweat glands during a stressful laboratory situation, carried out to demonstrate the applicability of this technique in field research and laboratory, and to determine whether or not the Palmar Sweat Index (PSI) is a sensitive stress-induced activation measure. The experiment involved six phases: I-adaptation, IIrelaxation, III-stress (mental arithmetic), IVrelaxation, V-stress (watching a distressing film), and VI-relaxation; during all periods, except stress phases, subjects were told to relax. PSI increased significantly from relaxation to stress, and decreased after its cessation. We conclude that the measurement of the PSI is sufficiently objective and that the variable in question is a very sensitive indicator of autonomic reactivity. In addition, the number of open glands may be a useful measure related to electrodermal response frequency when polygraph measurement it unavailable.