The data on correlation of Wechsler intelligence indices with signal differentiation speed shown by 5 samples of 11-years old schoolchildren are presented. Three interrelated factors influence this correlation: markerness of correlation between different tasks on signal differentiation; the degree of intercorrelarion of intelligence subtests; the level of intelligence development. It is argued that less developed intelligence is characterized by united general level of signals and their correlation differentiation. The data obtained are theoretically considered to be in accordance with the notion of cognitive structures being the carriers of intellectual abilities.