Some confounding factors in the study preparatory set in reaction time.

In Experiment I. the effects of the range of the distribution of preparatory intervals (Pls) on the effect of PI on RT was demonstrated, and disparate conclusions about the development of preparatory set were thereby accounted for to some degree. In Experiment II. both range of the PIs and their average value were examined in a factorial design for their effects on RT. and it was concluded that, for any average value, greater range will result in greater PI effects; and for any range, greater average values will result in smaller PI effects on RT.