The Illusion of the Curveball


My latest post is up at Wired Playbook, describing the optical illusion we commonly refer to as the curveball:

The average curveball hurls toward a batter at around 75 mph, accentuated by a 1500 rpm spin. From the moment the ball leaves the pitcher’s hand, it travels a smooth, consistent, parabolic arc. There’s no disjointed change in its motion from beginning to end.


Yet as the ball nears home plate, the batter observes a sudden jump in its trajectory, the notorious “break.” A new study in PLoS ONE argues that the discrepancy between the physics and the perception of the curveball may be all in the mind — or, more specifically, an optical illusion created by the batter’s eyes and brain.

Read the entire story here.

photo via Flickr/Matt McGee

Shapiro, A., Lu, Z., Huang, C., Knight, E., & Ennis, R. (2010). Transitions between Central and Peripheral Vision Create Spatial/Temporal Distortions: A Hypothesis Concerning the Perceived Break of the Curveball PLoS ONE, 5 (10) DOI: 10.1371/journal.pone.0013296

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