The expression “embodiment of tool” indicates skillful manipulation of tool, and the expression “instrumentalization of body” indicates the body does not move as intended. Each situation is located in different regions and might give opposite impressions, on the other hand the author considers positive meanings for them as equivalent states while introducing our research topics of designing tools that expand the possibilities of experience.

  First, designing tools is considered from the perspective of an autopoiesis system, in which the self is produced through experience. This means that the standpoint changes from “I use a tool” to “I am produced newly through using the tool”. Moreover, a mechanism is designed that re-organizes the user’s relationship with the tool or the environment through using the tool.

  In designing for what can be done, the methods are introduced to support search of skill acquisition by oneself, including bicycle pedaling skills. The feature of this approach is to utilize differences in body movements and images, set workable boundaries and organize movements step by step in interaction.

  In designing for giving a meaning to what people are unable to do, the methods are introduced for simulating experience that hemiplegia patients have. The temporary reduction in physical function indicates a meaningful approach that makes it easier to direct attention toward movements that are normally automatic.

  Finally, in designing for expanding the options of what can be done, the authors have devised an approach to increase the variety of manipulations by adjusting the degree of freedom of operations while using the interface system, and applied this idea for the bimanual cooperative interface systems.

  Based on the above, the author considers that the potential for athletic ability could be extended by dynamically transitioning between the two states : the embodiment of tool and the instrumentation of body.

  Skilled performers in sports, dance, music possess domain-specific cognitive-motor function. The body, which supports skilled performance, is a complex and exquisite system composed of a vast number of cells and a variety of role-differentiated tissues. Human movements are built on multiple levels based on the basic structure of physical development, with the more basic levels serving as a background to underpin the higher levels to achieve advanced motor skills. The fundamental level of hierarchical movement construction includes tension/relaxation, posture, breathing, equilibrium, and is positioned as a common ground in various physical performances. Moreover, movement is generated amongst various external environments and various internal environments, and utilization of all these internal and external environmental resources is necessary to realize advanced performance. Since the possibility of action is perceived by the functional unit of the body-environment system, it is necessary to reconsider the exploration for action resources and the hierarchy of movement construction from the viewpoint of the body extending into the environment.