Figure 1.

Representative models of baseball (A) and tennis (B) fields, players, and match development. The arrows indicate the visual burden: (A) the two-way arrows between the pitcher and the batter show the mutual visual focus before and during the throw action of pitcher; the outfield players wait for the throw development (arrows directed from outfield players to the pitcher); (B) the visual burden is limited to the ball and the opponent’s movements (both arrows from the player directed to the ball and the opponent).