The authors retracted this article because its theoretical basis, some of its text, and some of its figures and tables substantially overlap with the following previously submitted article:

Motivated optimal developmental learning for sequential tasks without using rigid time-discounts, Dongshu Wang, Yihai Duan, Juyang Weng, IEEE Trans. on Neural Networks and Learning Systems, published online 11/01/18, https://doi.org/10.1109/TNNLS.2017.2762720, http://ieeexplore.ieee.org/document/8253855/.

All authors of this article agree to this retraction. The online version of this article contains the full text of the retracted article as electronic supplementary material.