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I’ve noticed that even the best players in the world, and the
umpires, consistently make bad calls at the Australian Open. The
vast majority get their Hawk-Eye challenges wrong, just like we seem
to in regular play. Why?
Your question brings back unpleasant memories of
McEnroe’s tantrums over calls.
For an answer to your question, we can turn to vision scientists at
the University of California Davis who studied ‘bad calls’ from the
2007 and 2008 Wimbledon Championships. They used slow-motion replays
and Hawk-Eye to study 83 erroneous calls in which the ball landed on
or very close to the line. Hawk-Eye, while not as sophisticated as
IBM’s Big Blue, the chess computer, uses mathematics to calculate
the ball’s flight path to make a call.
As it turns out, it's not a matter of incompetence as McEnroe
famously asserted. Rather, the human brain is hard-wired to misread
the true position of fast-moving objects, including tennis balls –
possibly part of our ‘fight or flight’ survival mechanism. It takes
about 100 milliseconds for the image of the ball to travel from the
retina to the visual cortex and a little longer for the brain to
process it. The brain compensates for that delay by anticipating the
object's location – literally filling in the blanks.
The inevitable result in tennis, is that both players and umpires
often perceive a ball as being farther along in its trajectory than
it actually is, particularly those shots hit with heavy spin that
drop very quickly at the end. The problem is further compounded by
the shorter player who can lack depth perspective due to parallax.
Without the brain’s inbuilt compensation, players and umpires would
be likely to misjudge balls that are in and balls that are out
equally. Instead, the scientists found that 70 of the errors -- or a
staggering 84% (2007) and 69% (2008) -- were made when balls were
called "out" but were actually in.
Cheating aside, bad calls are probably evenly distributed during
play, limiting their effect. However that doesn't mean that they
don't influence the outcome of a match; witness the effect of a bad
call on even a world-class player’s psyche!
So when should the players challenge Hawk-Eye? No it’s not when the
player’s entourage makes a call from the player’s box! Rather the
scientists concluded that tennis players should focus on challenging
calls when they believe the ball was incorrectly called out, since
they are more likely to be vindicated by the infallible Hawk-Eye.
For regular players, perhaps there are even greater lessons to be
learned? Perhaps we should take a ‘time out’ before we ‘attack’ our
opponents for making a ‘deliberate’ bad call. Perhaps the ‘unsighted
rule’ which requires us to give the benefit of our doubts to our
opponents is closer to the truth than we might have believed.
(c) Rob Muir USPTA
December 21, 2009 |
