The effect of prehabituation of the prepulse on
startle eyeblink modification was studied in two experiments.
In Experiment 1, college student participants were either
prehabituated or nonhabituated to a tone that served as
a prepulse in a startle modification passive attention
paradigm. Neither short lead interval (60 and 120 ms) prepulse
inhibition (PPI) nor long lead interval (2,000 ms) prepulse
facilitation (PPF) was affected by the prehabituation procedure.
In Experiment 2, participants were presented with an active
attention paradigm in which one of two tone prepulses was
attended while the other was ignored. One group was prehabituated
to the prepulses and the other was not. Unlike the results
with the passive paradigm in Experiment 1, prehabituation
did significantly diminish attentional modulation of PPI
and PPF. These results are consistent with the hypothesis
that passive PPI and PPF are primarily automatic processes,
whereas attentional modulation involves controlled cognitive
processing.