This study focuses on the perceptual skills used when playing kendama, a toy with a ball, string, and handle. It examines the visual information required for guiding the head and handle movements during the “swing-in” catching maneuver and determines whether information-based strategies such as canceling the rate of change of α (the optical depression angle from the horizon) or cot α (optical acceleration), using tau coupling, or a combination thereof, could be applied to this empirical task. The regressions of both α and cot α with time are found to be highly linear and increase when the skill level increases. For expert players, the k values for the tau coupling based on the center of the ball are clearly lower than those for the tau coupling based on the hole in the ball compared with skilled players. These results suggest that, with increasing skill level, kendama players tend to utilize α or cot α for regulating the observation point and use the sight of the hole as the tau coupling information for controlling the handle.

【目的】 ヒトは、発達段階で視覚と体性感覚の知覚システムを同時に動員し能動的に動くことでそれらの協調を学習し、様々な環境に対して適応可能になる。今回我々は、自分の身体と支持面を見ながら能動的に動く動作が、視覚と体性感覚の協調に与える影響を姿勢制御の観点から検討した。<br>【方法】 対象は、藤田保健衛生大学倫理審査委員会の承認（10-204）の下、同意を得た健常男性40名（平均年齢22.4±2.3歳）を10名ずつ揺すり、背臥位、腹臥位、腹臥位視覚遮断（腹臥位と同一の対象）、筋トレの5群に分類。重心動揺計（サンプリング周波数10Hz）を用いて、a；視覚情報統制条件とb；鉛直情報呈示条件で30秒間の静止立位時の、c；上肢水平挙上、d；点へのリーチ、e；面へのリーチ条件で15秒間のリーチ姿勢保持時の、単位面積軌跡長（以下、L/A）を計測。各群における治療前後での変化の平均値を算出した。<br>【結果】 各条件におけるL/A（/㎜）の治療前後での変化の平均値を群ごとに示す。<br>揺すり群：a；0.07, b；0.26, c；-0.11, d；-0.01, e；0.22<br>背臥位群：a；-0.07, b；0.11, c；-0.10, d；0.18, e；0.33<br>腹臥位群：a；0.27, b；0.29, c；0.57, d；0.16, e；-0.21<br>腹臥位視覚遮断群：a；-0.06, b；0.16, c；-0.11, d；0.20, e；0.82<br>筋トレ群：a；-0.05, b；0.06, c；-0.49, d；-0.37, e；-0.56<br>【考察】 L/Aは動的、静的な姿勢制御を識別し、その程度を示す微細さの指標となる。L/Aが増加する場合、運動の拡がりに拮抗する筋活動で制御するCA（カウンターアクティビティ）の戦略が優位に、L/Aが減少する場合、支点に対して反対側の重りで釣り合いをとり静的に制御するCW（カウンターウェイト）を活性化する戦略が優位になると考えている。ここで静止立位課題について、bでは全群でCA優位となり、視覚的構造物が空間的定位の指標になったと考えられる。その内、揺すり、腹臥位群はa, bともに、すなわち視覚情報量の大小に関わらずCA優位であり、1つの知覚システムが優位に作用することなく視覚や体性感覚といった複数の知覚システムが協調したためと推察される。一方、背臥位、腹臥位視覚遮断、筋トレ群ではaでCWの活性化が優位となり、視覚情報量の差でバランス戦略が異なるため、視覚と体性感覚が乖離したと考えられる。次にリーチ姿勢保持に関して、cは腹臥位群のみ、dは背臥位、腹臥位、腹臥位視覚遮断群、eは揺すり、背臥位、腹臥位視覚遮断群でCA優位となった。腹臥位群に着目すると、身体の質量バランスが不均衡となり体性感覚への負荷が高まるcと、視覚と体性感覚に対する拘束力が強まるdでCA優位となり、体性感覚だけでなく視覚と協調しながら柔軟な姿勢制御が可能であったと考えられる。また漠然とした注意の中、広い面に触れていれば良いという体性感覚が強く作用するeでは、体性感覚の反応に視覚の反応を沿わせたためCWの活性化が優位になったと考える。<br>【まとめ】 腹臥位群のように絶えず身体と支持面の変化を見ながら能動的に動く動作により、各々の環境・条件での姿勢制御が視覚と体性感覚に対する情報量に、よりダイナミックな適応を示した。視覚と体性感覚の協調を図る運動療法の新たな展開が期待できる。

We examined the role of postural control in a skilled task that requires perceptual-motor coordination, the kendama trick "Swing-in," which uses a moving ball on a string. Four expert and 4 novice players participated, each performing 200 trials of Swing-in. The head and knee movements of the experts were more extensive than those of the novices, and the movements of the head and the ball, as well as the knee and the ball, maintained the same patterns longer in the experts than in the novices. At the end of each trial, distances between the head and the ball in the expert group were more consistent than those in the novice group, but the 2 skill groups showed similar variability in distance between the knee and the ball. These findings suggest that kendama experts controlled their body movement to dynamically coordinate them with the moving ball, and the stability of the strong coupling of the head and the ball in the experts seemed to be supported by the flexibility of knee movement.

We frequently observe occasions when breathing is intentionally controlled to match to concurrent body movement. This study reports on two experiments conducted to examine the stability and variability in the coordination of breathing with wrist-movements, with an inverted pendulum held in the hand. In Experiment 1, two modes of stable coordination of breathing and wrist-movement were identified: (1) the wrist was radially-flexed during inspiration and ulnarly-flexed during expiration; and (2) the wrist was ulnarly-flexed during inspiration and radially-flexed during expiration. In Experiment 2, subjects coordinated breathing and wrist-movements as three factors (phase mode, oscillatory frequency of breathing/wrist-movements, the eigen frequency of the pendulum) were manipulated. The results indicated that the coordination of breathing and wrist-movement exhibits patterns predicted by HKB-equation (e.g., phase transitions from the intended phase mode to the unintended mode). We suggest that breathing and wrist-movement together constitute a self-organizing system and that they are governed not only by the central nervous system but are also constrained by dynamical principles.

This study examined the stability and variability of interpersonal coordination, in which one person breathed while the other moved a wrist back and forth with an inverted pendulum in hand. Nine pairs of subjects coordinated each other's movement in two relative phase modes. In one mode, Radial flexion-Inspiration and Ulnar flexion-Expiration (RIUE), one subject radially flexed the wrist as the other inhaled and ulnarly flexed it as the other exhaled. In the other, Ulnar flexion-Inspiration and Radial flexion-Expiration (UIRE) mode, the wrist was ! ulnarly flexed at inhalation, and radially flexed at exhalation. Results were as follows: (1) The two were more highly coordinated in RIUE mode than UIRE mode as the frequency of oscillation increased. (2) Phase transitions were observed from URIE to RIUE mode, as the frequency of oscillation increased. And (3) the more different in preferred frequency the pendulum and breathing movements were, the more deviated from the intended relative phase the coordination became. These results suggest that interpersonal coordination of breathing and wrist-pendulum movement is qualitatively equivalent to intra personal coordination between them.

J. J. Gibson (1979/1986) proposed that animals perceive 'affordances', which are the functional utilities based on the properties of both the animals and the environment. If this is the case, animals should make judgements about what to do referring to the capability of their own action system. In this study, I examined a perceptual boundary between "stepping-over" and "passing-under" for two groups-the tall group and the short group. Subjects were individually requested to judge whether they would "stepover" or "passunder" a bar presented in front of them which was varied in height. I found that the mean bar-height to leg-length (B/L) ratio at the perceptual action-switching-point is invariant, or 1.07, for each group. This result suggests that animals perceive affordances in controlling action, which means that the environment for animals is structured as to various levels of action.