Interaction of time-uncertainty and relative signal frequency in determining choice reaction time

Choice reaction times (RTs) to 2 signals of relative frequencies .2 and .8 were measured under 2 time-uncertainty conditions: constant foreperiods of either .5 or 5.0 sec. The RT to the more frequent signal is more affected by time uncertainty than the RT to the less frequent one. This result shows that "preparation," a hypothetical state which has often been postulated to account for time-uncertainty effects, is at least in part specific to 1 particular signal-response pair, or, alternatively, that the well-known effect of signal relative frequency is affected by very short-term fluctuationsSCOPUS: ar.j