Principal component analyses were performed on reactions times (RTs) in relation to preparatory intervals (PIs) in 6 different series. These data were discussed in terms of the hypothesis that various aspects of RT set are distinguishable, different in meaning, and independent. Set, as inferred from the relations between RT and PI, was independent of sense modality. (PsycINFO Database Record (c) 2006 APA, all rights reserved)