Editing Curveball (section)

==Real or illusion?==
There was once a debate on whether a curveball actually curves or is an [[optical illusion]]. In 1949, Ralph B. Lightfoot, an aeronautical engineer at [[Sikorsky Aircraft]], used wind tunnel tests to prove that a curveball curves.<ref>{{cite web|url=http://www.phschool.com/science/science_news/articles/pitching_science.html |title=Pitching Science – Engineers who track baseballs catch insights into the game |publisher=Phschool.com |date=2001-06-09 |access-date=2010-10-27}}</ref> On whether a curveball is caused by an illusion, [[Baseball Hall of Fame]] pitcher [[Dizzy Dean]] has been quoted in a number of variations on this basic premise: "Stand behind a tree 60&nbsp;feet away, and I will whomp you with an optical illusion!"

However, optical illusion caused by the ball's spinning may play an important part in what makes curveballs difficult to hit. The curveball's trajectory is smooth, but the batter perceives a sudden, dramatic change in the ball's direction. When an object that is spinning and moving through space is viewed directly, the overall motion is interpreted correctly by the brain. However, as it enters the peripheral vision, the internal spinning motion distorts how the overall motion is perceived. A curveball's trajectory begins in the center of the batter's vision, but overlaps with peripheral vision as it approaches the plate, which may explain the suddenness of the break perceived by the batter.<ref>{{cite web |author=2009finalist |url=http://illusioncontest.neuralcorrelate.com/2009/the-break-of-the-curveball/ |title=2009 Vision Sciences Meeting: Curveball Demo Wins Illusion Contest |publisher=Illusioncontest.neuralcorrelate.com |date=2009-05-10 |access-date=2010-10-27 |url-status=dead |archive-url=https://web.archive.org/web/20101027064948/http://illusioncontest.neuralcorrelate.com/2009/the-break-of-the-curveball/ |archive-date=2010-10-27 }}</ref><ref>{{cite web|url=https://www.newscientist.com/article/mg20227114.300-revealed-why-curve-balls-are-so-hard-to-hit.html |title=Revealed: Why curveballs are so hard to hit |publisher=New Scientist |date=2009-06-07 |access-date=2010-10-27}}</ref><ref>{{cite news|author= |url=https://www.wired.com/playbook/2010/10/curveball-illusion/ |title=A Curveball's Curve? It's All in Your Head |publisher=Wired |date= 2010-10-19|access-date=2010-10-27}}</ref><ref>{{cite web |url=http://uscnews.usc.edu/science_technology/breaking_curveball_too_good_to_be_true.html |title=Breaking Curveball Too Good to Be True – USC News |publisher=Uscnews.usc.edu |date=2010-10-13 |access-date=2010-10-27 |url-status=dead |archive-url=https://web.archive.org/web/20101023013800/http://uscnews.usc.edu/science_technology/breaking_curveball_too_good_to_be_true.html |archive-date=2010-10-23 }}</ref> A peer-reviewed article on this hypothesis was published in 2010.<ref>{{Cite journal|title=Transitions between Central and Peripheral Vision Create Spatial/Temporal Distortions: A Hypothesis Concerning the Perceived Break of the Curveball |journal=PLOS ONE|volume=5 |issue=10 |pages=e13296 |date=2010-10-13 |doi = 10.1371/journal.pone.0013296|pmid=20967247 |pmc=2954145 |last1 = Shapiro|first1 = Arthur|last2=Lu |first2=Zhong-Lin |last3=Huang |first3=Chang-Bing |last4=Knight |first4=Emily |last5=Ennis |first5=Robert |bibcode=2010PLoSO...513296S|doi-access=free}}</ref>