Td. Blumenthal, INHIBITION OF THE HUMAN STARTLE RESPONSE IS AFFECTED BY BOTH PREPULSEINTENSITY AND ELICITING STIMULUS-INTENSITY, Biological psychology, 44(2), 1996, pp. 85-104
The present study evaluated the effects of the intensity of prepulses
and eliciting stimuli on the modification of the adult human acoustic
startle eyeblink. Eyeblinks were elicited by 85, 95, and 105 dB(A) noi
se bursts, preceded on some trials by 60 or 70 dB(A) tones at a 120 ms
stimulus onset asynchrony. Prepulse intensity was a within-subject va
riable in Experiment 1 (N = 19) and a between-groups variable in Exper
iment 2 (N = 38). For no-prepulse trials, as startle stimulus intensit
y decreased, startle amplitude, probability, and magnitude decreased,
and startle latency increased. As startle stimulus intensity decreased
from 105 to 95 dB, the amount of inhibition of response amplitude and
magnitude remained stable for 70 dB prepulses in Experiment I and for
both 60 and 70 dB prepulses in Experiment 2, whereas inhibition of re
sponse probability became more pronounced. As startle stimulus intensi
ty decreased from 95 to 85 dB, prepulse inhibition of response amplitu
de and magnitude lessened and inhibition of response probability becam
e still more pronounced in both experiments. These data show that the
inhibition of startle can be affected by eliciting stimulus intensity,
and that startle response amplitude and probability are affected by s
timulus intensity changes in different ways.