Effects of variations in the preparatory interval on the reaction time of retardates and normals.

Conducted 2 studies to evaluate the effects, on simple RTs, of warning signal duration (WSD) and preparatory interval (PI) with normal and mentally retarded Ss. In Exp. I PIs of 2, 4, 8, and 12 sec. were presented in an unpredictable sequence. For 1/2 of the Ss the warning signal remained on throughout the entire PI (filled condition) and for the remainder of the Ss, the warning signal was present for only 1.5 sec. of the PI. Significant effects of intelligence, PI, and WSD were found. The interaction Intelligence * PI was also significant. The unfilled condition resulted from produced faster RTs for both normals and retardates. The interaction resulted from the particularly poor performance of the retardates at the short PIs. Exp. II employed a 1.5 sec WSD with PIs of 2, 4, 8, 16, and 32 sec. An interaction was found involving intelligence and PI. Results are discussed in terms of temporal uncertainty. (PsycINFO Database Record (c) 2010 APA, all rights reserved)