Individual Differences in the Cardiac Response to High Intensity Auditory Stimulation

A recently reported long latency cardiac acceleration to the initial presentation of a high intensity white noise stimulus was investigated further with pure tones. In three experiments (involving 128 subjects) marked individual differences in the secondary response were uncovered. Many subjects not showing acceleration exhibited a secondary deceleration. Subjects were categorised into Accelerators, Decelerators, and a non‐consistent‐change group on the basis of cardiac activity in a 17‐50 s poststimulus epoch. While both Accelerators and Decelerators exhibited short latency cardiac acceleration, it was of greater magnitude in the former. The long latency response is discussed with reference to a distinction between the defensive reflex and the fight/flight response. Discussion of the short latency response focuses on the startle reflex and the‘What's‐to‐be‐done?’component of the response to a novel stimulus.