Calculating Dogs

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dipdude

Forerunner
It all started with Elvis.

In 2003, mathematician Tim Pennings of Hope College in Holland, Mich., revealed to the world that his Welsh corgi, Elvis, appears to be solving a calculus problem when finding the optimal path to fetch a ball. In this case, optimal path means minimizing travel time.

When Elvis and Pennings go to the beach, they always play fetch. Standing at the water's edge, Pennings throws a tennis ball out into the waves, and Elvis eagerly retrieves it. When Pennings throws the ball at an angle to the shoreline, Elvis has several options. He can run along the beach until he is directly opposite the ball, then swim out to get it. Or he can plunge into the water right away and swim all the way to the ball. What happens most the time, however, is that Elvis runs part of the way along the beach, then swims out to the ball.

Depending on the dog's running and swimming speeds, the strategy that Elvis follows appears to minimize the time that it takes to get to the ball. Indeed, Pennings found by experiment that Elvis performs in a way that closely matches a calculus-based mathematical model of the situation.

Now, several other researchers have weighed in on the question of what sort of calculations dogs may do to reach their goals.

In the January College Mathematics Journal, Pierre Perruchet of the University of Bourgogne and Jorge Gallego of Robert-Debre Pediatric Hospital in Paris contend that the model chosen by Pennings assumes that the dog knows the entire route in advance in order to minimize the total duration of travel. Instead, they say, a dog optimizes its behavior on a moment-to-moment basis.

Perruchet and Gallego worked with a female Labrador named Salsa, who, like Elvis, apparently chooses the optimal path when playing fetch along a lakeside beach—in this case, near Nimes, France.

The researchers suggest that a dog playing fetch chooses at each point in time the path that allows it to maximize its speed of approach to the ball.


For more details, equations, confusion, scientists derivations visit ScienceNews
 
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