Does stimulus intensity and repetition affect cardiovascular activity and indicate a transition from orienting to defense reflex?
Stimulus intensity and repetition reliably affect cardiovascular variables like heart rate and pulse amplitude, though they do not clearly differentiate orienting from defense reflexes.
ABSTRACT A between‐groups design (N = 75) was employed to investigate the effects of stimulus intensity and repetition on cardiovascular activity. It was predicted that as intensity increased, the pattern of physiological activity would change, indicating a transition from the orienting to the defense reflex. Cardiovascular activity was represented by measures of heart rate, digital pulse amplitude, and cephalic blood content. Subjects received 12 presentations of a 1000 Hz tone of 45, 60, 75, 90, or 105 dB. Stimulus risetime was 30 msec and the duration 2 sec. Analyses of variance revealed reliable effects of intensity and repetition on all cardiovascular variables. However, neither these results nor additional multivariate analyses supported the differentiation of orienting and defense reflexes as suggested by Sokolov (1963) or Graham (1979). The importance of the startle reflex in the interpretation of these findings was discussed.
Turpin et al. (Tue,) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: