FOREPERIOD DURATION, RANGE, AND ORDERING EFFECTS ON ACOUSTIC LRT IN NORMAL SPEAKERS

One quantitative measure of vocal motor control is phonation onset lat ency relative to presentation of an external stimulus in a reaction ti me task. However, variables within the design of reaction time experim ents can affect laryngeal reaction time (LRT) values. The present stud y examines effects of foreperiod characteristics on LRT for normal spe akers. Foreperiod is the interval between presentation of warning and response cues. LRT was affected by absolute foreperiod duration, by th e average foreperiod duration of a block of trials, and by the orderin g and range of foreperiods within a block of trials. Results are discu ssed with respect to foreperiod effects on the subjective expectancy a nd objective probability of occurrence of the response cue and on the timing of neurophysiologic processes. Control of subjective effects is critical to assessment of neurophysiologic constraints on LRT.