CEPHALIC VASOMOTOR AND HEART RATE MEASURES OF ORIENTING AND DEFENSIVE REFLEXES

The problem of differentiating orienting (OR) and defensive reflexes (DR) was investigated by measurements of forehead‐skin pulse amplitude (PA), forehead‐skin blood content (BC), and heart rate (HR). Thirty male college students received 30 stimulations of .5 sec white noise at either 80 db or 120 db. Beat‐by‐beat analyses of the physiological measures indicated that both intensities of stimulation produced decreases in PA. Forehead BC showed larger increases to 120 db than to 80 db, and successive stimulations produced a change to overall decreases in BC at both intensities. HR acceleration occurred to both stimuli, and a short‐latency deceleration occurred to 80 db. The results were interpreted as showing that cephalic vasoconstriction is the dominant response to auditory stimulation, and cephalic vasomotor responses do not differentiate between ORs and DRs. The short‐latency HR deceleration and smaller HR acceleration differentiated the OR from the DR. Copyright © 1969, Wiley Blackwell. All rights reserved