Effects of foreperiod duration on reflexive and voluntary responses to intense noise bursts

Author(s): Hackley, S. A.

Journal/Book: Psychophysiology. 1997; 34: 1010 Vermont Ave NW, Suite 1100, Washington, DC 20005. Soc Psychophysiol Res. 518-526.

Abstract: The question of whether a common mechanism underlies the facilitation of voluntary and reflexive reactions by a warning stimulus was investigated in two experiments. In both studies, the foreperiod preceding an intense noise burst was manipulated within and between blocks of trials. Previous reaction time experiments have shown that individuals respond fastest at the shortest foreperiod for between-block manipulations and fastest at the longest foreperiod when foreperiod duration is varied unpredictably from trial to trial. In the present research, this pattern was found for voluntary hand-grip responses, but acoustic startle blinks were facilitated at long foreperiods for both within-and between-block manipulations. Invariance of the trisynaptic postauricular reflex across foreperiod conditions was evidence against any general activation of low-level motor pathways by warning stimuli. Analyses of nonreflexive lid movements subsequent to startle blink suggested that inhibition of spontaneous blinking during the foreperiod may have contributed to the unexpected divergence between voluntary reactions and eyeblink reflexes.

Note: Article Hackley SA, Univ Missouri, 210 Mcalester Hall, Columbia,MO 65211 USA

Keyword(s): alerting; immediate arousal; auditory attention; brain stem; expectancy; orbicularis oculi; EMG; WEAK PRE-STIMULATION; BLINK; EXCITABILITY; EYEBLINK; TIME

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