The Perceptual Illusion of
Baseball's Rising Fastball

Terry Bahill
Dave Baldwin
Systems and Industrial Engineering
University of Arizona
Tucson, AZ 85721-0020, USA
terry@sie.arizona.edu
http://www.sie.arizona.edu/sysengr/slides/risingFastball.ppt
© 1998-2005 Bahill

A rising fastball is impossible according to principles of physics and physiology: yet many batters claim it exists. They say the ball jumps a half-foot right in front of home plate. Our model suggests that rising fastballs are perceptual illusions caused by the batter underestimating the speed of the pitch. This model uses only signals from known primary visual processes. Although the numbers given in this paper are for professionals, the model applies to all players, right down to Little Leaguers. The model can also be extended to cricket. A sensitivity analysis has shown that the model is robust with respect to its parameter values. The most sensitive parameter is the estimated speed of the pitch.

Critical flicker fusion frequency might explain the difference between two-seam and four-seam fastballs.

References [56 and 83]. This lecture is suitable for engineers, psychologists or the general public. This talk requires PowerPoint and a computer projection system. This talk takes one hour.