An attempt "to discover the shape of the range-effect error curve and the shape of the distributions of response errors under conditions of varying speed stress resulting from increasing stimulus frequency." Found the range-effect curve to be S shaped on the average and not linear; the distributions of error at each input amplitude were near zero and skewed toward the mean of the input distribution; and under conditions of lower speed stress the range-effect decreases. (PsycINFO Database Record (c) 2006 APA, all rights reserved)