About the Authors

Toru Nakamura

Affiliation Graduate School of Education, University of Tokyo, Tokyo, Japan

Toru Takumi

Affiliation Graduate School of Biomedical Science, Hiroshima University, Hiroshima, Japan

Atsuko Takano

Affiliation Research Center for Child Mental Development, Osaka University, Osaka, Japan

Fumiyuki Hatanaka

Affiliation Graduate School of Biomedical Science, Hiroshima University, Hiroshima, Japan

Yoshiharu Yamamoto

yamamoto@p.u-tokyo.ac.jp

Affiliation Graduate School of Education, University of Tokyo, Tokyo, Japan

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: TT YY. Performed the experiments: AT FH. Analyzed the data: TN. Contributed reagents/materials/analysis tools: TN. Wrote the paper: TN TT YY.