In 3 experiments, children of 5 or 7 years old were successively given S (stimulus figure) -V (label) training, V-R (motor response) training, S-R training and the mediation test in accordance with modfied 3-phases mediation paradigms. It was found that in children of 5 years old V-R training had no significant effect on the occurence of the mediated responses, while in children of 7 years old it had the facilitative effect on it, and that in 5 years the overlearning in V-R training had no effect on the mediational performance, while the overlearning in S-V training had the facilitative effect.