ASA 125th Meeting Ottawa 1993 May

2aSP4. Foreperiod effects on acoustic laryngeal reaction time.

Ben C. Watson

Dept. of Otolaryngol., New York Medical College, Munger Bldg., #170, Valhalla, NY 10595

In a simple reaction time task, foreperiod is the preparatory interval between presentation of a warning cue and a respond cue. Two studies examined effects of foreperiod duration, range, and distribution on laryngeal reaction time (LRT) values for production of the isolated vowel /a/. The first study examined foreperiods presented in two series with different durations and ranges (200--1000 ms and 700--2300 ms). Each series had a rectangular distribution. The second study examined the same two foreperiod series presented in nonaging (equi-probable) distributions. Variable inter-stimulus intervals and subject instructions inhibited initiation of preparation prior to presentation of the warning cue. Laryngeal reaction time (LRT) values decreased as foreperiod increased in each series. LRT was longest after the shortest foreperiod in a series, regardless of its absolute length. The same absolute duration foreperiod (i.e., 700--1000 ms) yielded a longer LRT when it was embedded in a wider range of foreperiods. The quadratic relation between foreperiod duration and LRT [K. Izdebski, J. Speech Hear. Res. 23, 485--489 (1978)] was more pronounced when a series was presented as a nonaging distribution versus a rectangular distribution.