Electrographic reactions (GSR, EEG, ECG), the average school mark, and indices of reproduction and estimation of the 15-seconds interval were measured in 61 subjects first when in the I-st form and second when in the IX-th form (i. e. with the interval of 8 years). No sex differences at both age levels have been registered, however the measure of stimulus reproduction changed in girls to a larger extend than in boys (the values of reproduction in the first and in the ninth form do not correlate).