Experts' skill of clay kneading is experimentally studied. We focus on the timingofpressureappliedtoclaywithrespecttorockingmovementofthebody. Using a pair of foot pressure sensors and a weight sensor on the table, subjects' movements are measured. Differences between experts and beginners are discussed.

In this paper, we investigate how to discover knack in performing skillful tasks. Our approach is to formalize knack discovery problems in terms of abductive inference. We define two problems related to knack discovery: one is rule-abduction which tries to find missing rules to explain observed causality to accomplish hard performance tasks such as "increase sound volume" in playing the cello. The other is new knack discovery which suggests the learner where to focus attention during performance. We utilize an observed knack such as keeping right arm close during bowing which empirically proved to achieve the given task. We provide abductive inference programs to conduct both rule induction and new knack discovery. Especially, we point out the importance of existentially quantified logical formula to express hypotheses including logical variables representing missing nodes to be introduced.

The present paper discusses the necessity of athletes' thinking own body meta-cognitively, argues what kind process it is, and points out research issues involved in the process from the viewpoint of coaching and leaning environment.