本研究は, 男子大学野球部員20名を対象者とし,

    The purpose of this study is to examine the effect of “sacrifice bunt” in baseball, executed when a runner is on first base with no outs. The offensive strategies studied are, “sacrifice bunt”, “base stealing”, “hit-and-run”, “hitting”, and “hitting after first attempting to bunt”. We recorded 846 official games of Japanese Professional Baseball in 2006, and selected 3994 cases to categorize the strategies and the results. The results are as follows:
    （1） Following the bunts, the runner on first moved up to second base 81.6％ of the time, but the base runner advanced only 40.7％ after hitting.
    （2） However, following the bunts,the runner on first reached home plate 37.6％ of the time. This probability is almost the same as the one after hitting.
    （3） The expected number of runs in one inning for each strategy was: 0.73 for bunting, 0.86 for hitting, and 0.95 for the “hit-and-run”.
    There are possibilities that the effectiveness of five strategies are not the same as the result of (1) to (3), not in case of a league format and higher skill level. In this study, we didn’t discuss about each case with various situations, but examined many cases (3994) comprehensively. Based on our results we can see that it isn’t advisable to choose the “sacrifice bunt” in this situation. It seems that a more effective strategy for scoring runs is either hitting or executing the “hit-and-run”.

    This study investigates the catcherʼs throwing time to second base (time from the ball being caught to the completion time of the thrown ball reaching second base). The throwing motion of college baseball catchers (n=12) and the catching motion of a second baseman were videotaped at 210 Hz using different high-speed cameras. The throwing time was divided into the motion time (time from the ball being caught to being released) and the airborne time (time from the ball being released to the ball reaching second base). The motion time was further divided into the hold time (time from the ball being caught to the ball being held in the right hand), the stride time (time from the ball being first held in the right hand to the lead foot contact), and the release time (time from the lead foot contact to the ball release). To evaluate the throwing ability of the catchers, the throw distance was measured. There were no significant correlations between the throwing time and the motion time, but there were significant positive correlations between the throwing time and the airborne time. These results indicate the importance of increasing the initial velocity of the ball after release. There were no significant correlations between the throwing time and the hold time, or between the throwing time and the stride time. However, there were significant negative correlations between the throwing time and the release time, and the airborne time showed a significant negative correlation with the release time. These results suggest that catchers exhibiting the shorter the throwing times attempted to increase the initial velocity of the ball after release, although the release time became longer. Throw distance showed a significant negative correlation with the airborne time. These results clearly demonstrate the necessity of increasing throw distance to obtain a higher initial velocity of the ball at release.

　野球の

　不確定性のある中で行動を選択し実行する場面において、行動選択に対する確信度が高いほど選択された行動のパフォーマンスは高くなるのか？　例えば、野球の

【目的】厳しい時間的制約下で予測にもとづくプレー選択を迫られる状況では、予測の確度が十分に高くならなくても実行を決断せざるを得ないこともある。このとき、選択されたプレーのパフォーマンスはどうなるか。野球の

【方法】大学野球部員20名は、1塁ランナーとして投手の投球モーション映像を見て、打者への投球と判断したら2塁へスプリント、牽制と判断したら帰塁する課題を24試技実施した。走塁パフォーマンスは、

【結果】対象者内での分析結果とは異なり、平均確信度と平均映像タイムとの相関関係に有意性は認められなかった。選択反応時間と平均確信度は正の相関関係にあり、選択反応時間が長い対象者ほど、確信度は高かった。選択反応時間と平均映像タイムも正の相関関係にあり、選択反応時間が短い対象者ほど走塁は速かった。選択反応時間を制御変数とする偏相関分析は、平均確信度と平均映像タイム間の有意な負の相関関係を見出した。

【結論】選択反応時間の短いランナーは予測確度のスタート閾値が低く、走塁パフォーマンスは比較的高い。