3 ms·

For the dog optimising when to jump in the water, I think it's fairly easy to see how it does it. It's constantly optimising as it runs. It doesn't "choose" the

For the dog optimising when to jump in the water, I think it's fairly easy to see how it does it. It's constantly optimising as it runs. It doesn't "choose" the path and then run it. It's just repeating the same question as it moves, "is it worth running along the shore a bit more or should I just jump in now?"

hinkley 9y ago
Dogs are originally forest creatures. Whatever we bred into them we did initially because they were forest creatures. A few tens of thousands of years haven’t erased and in fact probably reinforce their instincts to solve pathing problems. Ravines and thickets must be circumscribed. Hillocks too, depending. Getting wet in the winter is better avoided so follow the stream and try to ford it later. It’s only preferable to going hungry. Play for time and min-max.
LeifCarrotson 9y ago
This would be more interesting if, instead of throwing the ball while standing at the water's edge, the human stood further back up the beach as in the lifeguard illustration. [1] This would require the dog to decide on the path to take at the start, or run in a path that wasn't a straight line. Anecdotally, when performing this experiment in the past, my dog typically runs directly towards the ball along the straight-line path Lifeguard->A, then turns somewhat along the edge of the beach to plunge in somewhere between A and C. I'm also curious if there is a confounding factor in the dog's motivation. Pennings states [2] that: > By the look in Elvis’seyes and his elevated excitement level, it seems clear that his objective is to retrieve itas quickly as possible rather than, say, to minimize his expenditure of energy. There is obviously a value that the dog ascribes to the expeditious retrieval of the ball, but when the ball is not present there's also a value to be had in simply running joyously on the sand, and, of course, there's little better than being in the water. We may therefore need to calculate the ideal path based on a static value (perhaps 100 dog-utilitons) for retrieving the ball, plus 2 du/m running in the sand, and 12 du/m when swimming in the water. This complicates the mathematics somewhat. Finally, the author's method of running ahead with a tape measure may work when measuring the performance of a short-legged subject, but I would be unable to use these methods to measure the performance of my larger and faster (Newfoundland) dog. Aerial drone videography may be more suitable instead. [1]: https://d3chnh8fr629l6.cloudfront.net/2904_b8b9c74ac526fffbeb2d39ab038d1cd7.png https://d3chnh8fr629l6.cloudfront.net/2904_b8b9c74ac526fffbe... [2]: https://webcache.googleusercontent.com/search?q=cache:l0DmOIr4uhsJ:www.indiana.edu/~jkkteach/Q550/Pennings2003.pdf+&cd=1&hl=en&ct=clnk&gl=us https://webcache.googleusercontent.com/search?q=cache:l0DmOI...
knodi123 9y ago
I assumed it was a matter of the dog desiring to go on a straight line directly towards the ball, and knowing that getting as close as possible by land will use less energy- but as he proceeds along land, his desire to head directly towards the ball increases due to anticipation, until eventually the force of anticipation grows larger than the resistance to excess effort. I bet as a puppy, he went in a straight line and ignored exertion, and as an elderly dog he'll minimize swimming time/effort, and as a middle-aged dog he's splitting the difference.

hinkley 9y ago

Dogs are originally forest creatures. Whatever we bred into them we did initially because they were forest creatures. A few tens of thousands of years haven’t erased and in fact probably reinforce their instincts to solve pathing problems. Ravines and thickets must be circumscribed. Hillocks too, depending. Getting wet in the winter is better avoided so follow the stream and try to ford it later. It’s only preferable to going hungry. Play for time and min-max.

LeifCarrotson 9y ago

This would be more interesting if, instead of throwing the ball while standing at the water's edge, the human stood further back up the beach as in the lifeguard illustration. [1] This would require the dog to decide on the path to take at the start, or run in a path that wasn't a straight line. Anecdotally, when performing this experiment in the past, my dog typically runs directly towards the ball along the straight-line path Lifeguard->A, then turns somewhat along the edge of the beach to plunge in somewhere between A and C. I'm also curious if there is a confounding factor in the dog's motivation. Pennings states [2] that: > By the look in Elvis’seyes and his elevated excitement level, it seems clear that his objective is to retrieve itas quickly as possible rather than, say, to minimize his expenditure of energy. There is obviously a value that the dog ascribes to the expeditious retrieval of the ball, but when the ball is not present there's also a value to be had in simply running joyously on the sand, and, of course, there's little better than being in the water. We may therefore need to calculate the ideal path based on a static value (perhaps 100 dog-utilitons) for retrieving the ball, plus 2 du/m running in the sand, and 12 du/m when swimming in the water. This complicates the mathematics somewhat. Finally, the author's method of running ahead with a tape measure may work when measuring the performance of a short-legged subject, but I would be unable to use these methods to measure the performance of my larger and faster (Newfoundland) dog. Aerial drone videography may be more suitable instead. [1]: https://d3chnh8fr629l6.cloudfront.net/2904_b8b9c74ac526fffbeb2d39ab038d1cd7.png https://d3chnh8fr629l6.cloudfront.net/2904_b8b9c74ac526fffbe... [2]: https://webcache.googleusercontent.com/search?q=cache:l0DmOIr4uhsJ:www.indiana.edu/~jkkteach/Q550/Pennings2003.pdf+&cd=1&hl=en&ct=clnk&gl=us https://webcache.googleusercontent.com/search?q=cache:l0DmOI...

knodi123 9y ago

I assumed it was a matter of the dog desiring to go on a straight line directly towards the ball, and knowing that getting as close as possible by land will use less energy- but as he proceeds along land, his desire to head directly towards the ball increases due to anticipation, until eventually the force of anticipation grows larger than the resistance to excess effort. I bet as a puppy, he went in a straight line and ignored exertion, and as an elderly dog he'll minimize swimming time/effort, and as a middle-aged dog he's splitting the difference.