“…Heart rate is probably the parameter that has been most frequently used, probably because palpitation is often reported by phobic clients and because it is rather easily measured in the laboratory and in in vivo situations. The interoceptive discrimination of changes in heart rate has, however, been reported to be rather low in normal, resting situations (Brener and Jones, 1974;Epstein et aL, 1977;Epstein and Stein, 1974;Clemens, 1979). Borkovec (1976) has described a self-rating scale originally developed by called the Autonomic Perception Questionnaire (APQ) where the client is to rate to what extent he/she perceives changes in different physiological parameters when feeling anxious.…”