Slo mo

Here's the story at normal speed: a dog chased a squirrel.

Nothing more to it than that.

In slow-motion, the story is considerably different.

Larsen nosed through the bushes in the back yard, and quick as a wink, a gray squirrel shot out of the garden, streaked across the lawn, and disappeared through the fence to the neighbor's sideyard.  Even in slo-mo, the squirrel was an absolute linear streak from point A to point B. 

Larsen sprang out in pursuit.   He quartered.  Now let me slow it down to super-slo-mo.  Each time Larsen crossed the squirrel's still-hot path in the yard I swear that I saw something register in Larsen's noggin.

Here in super-slo-mo, you can see a nano-second catch or spark each time Larsen crosses the squirrel's path.  It's like the path of the squirrel magnetically snaps Larsen's head toward the line of flight before Larsen catches himself and continues with his quartering.  This little catch occurs with each crossing until Larsen gets to the fence and faces the squirrel's last known (to me) position.

This whole thing took a second or two and was nowhere near as obvious as my description makes it seem.  It was very cool because you could see how quartering works on a neutral backdrop (a plain lawn).  It showed that the dog is not lost when he goes past the scent in a way that seems inefficient if you had an eye mark on the path.  It is more like he is reducing uncertainty about the path of the prey (since not every critter takes a straight line) and that he is tracking with his nose not his eyes.   

We return you now to normal speed.