[Seminar] From spontaneous to intentional action: measuring and modelling 3-month-olds’ behavior during environmental interaction, Prof. Ryo Fujihira, National Institute for Physiological Sciences

Prof. Ryo Fujihira, National Institute for Physiological Sciences

Title: From spontaneous to intentional action: measuring and modelling 3-month-olds’ behavior during environmental interaction.

Abstract:  Movement emerges spontaneously during the fetal period, followed by substantial motor development throughout early infancy. However, it remains unclear how the action becomes intentional. In this seminar, I will talk about two studies regarding this question: one is an experimental study and the other is a modelling study in dynamical systems.

In the experiment study, we measured electromyography (EMG), eye gaze, and pupil diameter in twenty 3-month-old infants interacting with a suspended toy. We found that pupil dilation, which initially occurred after movement onset, gradually shifted to precede movement initiation. This finding suggests that 3-month-old infants learn to predict outcome of their own actions and generate movements accordingly, potentially reflecting the emergence of intentional action through sensorimotor learning.

In our previous modeling study, we proposed a requisite for intentional action that can be described as bifurcation dynamics representing “to move or not to move.” This model reproduced experimental observations that infants increase limb movements when their actions produce environmental changes, but decrease them when no such contingency exists. This capability emerges around 3 months of age, possibly corresponding to the formation of thalamo-cortical circuits. Our model has successfully replicated the development of action differentiation; however, to make action intentional, one must change their behavior in the timing as they want, which further requires a meta-system to enable the choices of whether to act. I will introduce papers regarding this issue and discuss future directions.

Reference:

Fujihira, R., Shinya, Y., Watanabe, H., & Taga, G. (2025). The emergence of intentional action in early human infancy. bioRxiv, 2025-12.

Fujihira, R., & Taga, G. (2023). Dynamical systems model of development of the action differentiation in early infancy: A requisite of physical agency. Biological Cybernetics, 117(1), 81-93.

Watanabe, H., Homae, F., & Taga, G. (2011). Developmental emergence of self-referential and inhibition mechanisms of body movements underlying felicitous behaviors. Journal of Experimental Psychology: Human Perception and Performance, 37(4), 1157.

Brief bio:

Ryo Fujihira

National Institute for Physiological Sciences, Okazaki, Aichi

Division of Neural Dynamics, Project Assistant Professor

2020 Mar.  Bachelor degree, Department of Education, The University of Tokyo

2022 Mar.  Master degree, Graduate school of Education, The University of Tokyo

2025 Mar.  Ph.D (Education), Graduate school of Education, The University of Tokyo

Research Interest:

Dynamical Systems, Intention, Embodied Cognition, Infant Development, Synchronization