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Article History

Received: 24 April 2025

Accepted: 1 August 2025

First Online: 12 August 2025

Declarations

:

: There are no conflicts of interest.

: All procedures of the present study were approved by the Ethics Committee of the Graduate School of Humanities and Social Sciences, Kumamoto University (Reference number: 51; Title: Lifelong development of human perceptual-cognitive mechanisms and their neural basis) before running the study. The study was conducted in accordance with the principles of the Declaration of Helsinki (1964, 2013). Written informed consent was obtained from all participants before they commenced participation.

: The hand illustrations used in the figures are taken from the following Japanese internet site (). Before using them, we confirmed that the illustrations on this site can be used without permission for both non-commercial and commercial use, and are free for modification, while the copyright is held by the site owner. These statements are clearly documented on the following pages in Japanese ().