The mathematical activities of early elementary school children were classified according to the five categories presented by Ginsburg et al. (1999). Activties that did not fit into any of these five categories were classified as “other”; in total, 51.8％ of the activities were classified as “other” (Ishii, 2013). In Study1, a matrix display of children’s activities organized according to these six categories (i.e., the original five categories and the new “other” category) showed that the “other” category was connected to the five categories in three main patterns. In Study 2, case studies were interpreted to examine the characteristics and functions of the “other” category in relation to the five categories. The results suggested that when certain restrictions are placed on them for activities using objects, and that “stagnation of action" (Sasaki et al., 1992) occurs in the preliminary stages of activities while children are placing and moving objects or between these actions.

Virtual reality (VR) environments provide a high level of immersion, as if one were present in the image. However, the sensory information that contributes to the three-dimensional perception of VR images differs in part from that in real environments. The question of whether information that enables perception and action emerges even in an artificially created VR environment is fundamental in ecological psychology. In this paper, I introduce two topics to help consider this question. First, I provide an overview of the claims made by Baggs et al., published in Ecological Psychology in 2024, and summarize the immersion and interaction of VR images that they discussed. Second, I provide an overview of how VR images are used in research on perception and action related to locomotion. Based on these findings, I present an opinion about the immersion and interaction for VR images.

This paper aims to confirm the possibilities and limitations of understanding the impact of technology by "affordance" through a comparative study with the standard theory of understanding technology. While the theory of technology extension, which can be called the standard theory, has a track record of pioneering issues related to technology and becoming the basis for derivative theories, it is also recognized as having the defect of omitting the work of determining effects and proceeding with the discussion based on the premise of extensional effects. The affordance theories of technology, which can describe the transformation of the self through technology, can be combined with the extension theory in a way that contributes to the process of discernment, but this combination is not one-sided. Rather, it identifies the points of contact between the two theories, and shows that the affordance theory of technology also has the benefit of being combined, that is, it clarifies the complementary relationship between the two.

This study explains what affordance perception is and what should be done to study it, while in-troducing extant research and future research prospects. Affordance perception refers to the per-ception of affordances, which are possibilities or opportunities for actions. That is, it is the percep-tion of the relationship or compatibility between the properties of the environment and those of the actors. For example, a young person sitting on a guardrail or child sitting on the edge of a flowerbed achieves the act of “sitting” by perceiving the relationship or compatibility between the properties of the guardrail or edge of the flowerbed (height, material, etc.), and their properties (, leg length and flexibility, etc.). In this sense, the examples of affordance perception and the seeds of its study can be found everywhere in our living environment. By unraveling the mechanism of affordance per-ception, this study seeks to clarify the relationship between perception and action in animals, in-cluding among humans.

Dynamic touch is a key research focus within ecological psychology. This paper outlines its theoretical foundations by discussing (1) the mechanical invariants involved in dynamic touch, and (2) the hypothesis that the body serves as a haptic medium, organized as a multifractal tensegrity structure, with the entire body functioning as a unified perceptual system for touch. The paper also reviews experimental studies grounded in these theoretical foundations. In addition, it discusses the methodologies employed in dynamic touch research. The paper concludes by presenting additional relevant studies on dynamic touch, identifying its challenges, and proposing directions for future research methodologies.

This paper provides an overview of research on interlimb coordination, including specific methodologies. The human body is a complex system composed of numerous bones, muscles, and joints. Research on interlimb coordination has accumulated a wealth of studies focusing on how these complex components interact and produce movement. This paper begins by summarizing the concept of coordination and the motor control theory proposed by Bernstein (1967). Next, it provides an overview of the dynamical systems approach, which has played an important role in interlimb coordination research. It then provides a concrete explanation of experimental tasks, measurement methods, and analysis methods in interlimb coordination research. Finally, to illustrate the practical implications of the reviewed methodologies, this paper introduces the authors’ own research and offers perspectives on future research trajectories in interlimb coordination.

This tutorial explains behavioral synchrony, a phenomenon often observed in human interactions. Research on this subject emerged as late as the 1960s, revealing its adaptive functions including fa-cilitation and confirmation of rapport and social cohesion. Behavioral synchrony is further concep-tualized as a self-organizing stable pattern arising from the coupling between an individual and en-vironment through perceptual information. Additionally, for beginners in the field, this paper intro-duces fundamental methodologies and analytical tools for studying synchrony. It also describes the experimental design employed in one of the author’s previous studies, offering an example of syn-chrony research. Finally, as a perspective on research concerning behavioral synchrony and related higher-level concepts (coordination), this paper discusses its relationship with skill science and fu-ture challenges.

In psychology, "development" is often viewed as a stage-like or linear progression of physical, mental, and behavioral changes from childhood to adulthood. However, the changes that individuals undergo do not always align with textbook descriptions, nor do they unfold in a straightforward manner as if following a predetermined plan. While there are universal elements common to humans, each person experiences a unique and unprecedented process, shaping their own individuality. Ecological psychology focuses on the interaction between animals and their environment during this process. This paper first explains the development of affordance perception through Gibson and Adolph's research on locomotor development. Next, it introduces The Baby Movie Database to explore insights gained through observational studies in everyday environments. Finally, the paper presents methods for data collection and analysis and discusses the importance of bottom-up approach.