Monday 29 November 2010

You Cannot Be Serious

Congratulations to Roger Federer and his ATP Tennis final win this weekend in London but it got me thinking and researching from a Sports Vision point of view...

Linesmen are more likely to call a ball "out" when it was "in", rather than the other way. Why?

After an image is focused on the retina, there's a time delay of about 100 milliseconds before it is recreated in the brain. This is the image that we see, not the one on the retina.

Therefore, our perception of things lags fractionally behind reality. For moving objects, the visual system gets round this problem by shifting the image forward. This means that a tennis player can get their racket in the right place at the right time, and not fractionally late.

In theory then, when a ball bounces there's a likelihood that it will be perceived to have bounced further on (in the direction of travel) than it actually did.

To test the theory, Whitney et al (2008) reviewed more than 4,000 randomly selected Wimbledon points. They found 83 incorrect calls, of which 70 were of the type predicted.

The researchers suggest that players are therefore more likely to be successful challenging calls of "out" than calls of "in".

David Donner

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