Perception, 1990, volume 19, pages 545-552

The rising fastball: baseball's impossible pitch

Michael K. McBeath

Abstract

Batters in professional baseball are confronted with pitches that appear to curve, dip, wobble, or rise.  The rising fastball is a pitch where the ball appears to hop up as much as a third of a meter with a sudden increase in speed.  Physics experiments confirm that many reported trajectories are possible, but not the rising fastball.  The present paper shows how the apparent rise may be explained as a perceptual illusion due to the hitter underestimating original speed of the pitch.
 

Geometric representation of the rising fastball

Figure 1.  The illusion of the rising fastball.  Top trajectory indicates actual path of a fastball.  Bottom trajectory indicates path experienced by a batter who underestimates initial speed of the pitch.  Dotted lines show line of sight to the ball at equal temporal intervals.  Since  distance  to the ball is ambiguous, the line of site progression is consistent with both actual and experienced trajectories.  If correct line of site is maintained, the slower, experienced trajectory will also appear lower.  When the ball reaches home plate, its correct location can be accurately perceived.  Therefore, near the end of the experienced trajectory, the ball will appear to accelerate up with a hop

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