SUMMARY：

狗狗向左搖尾巴是開心，向右搖尾巴是討厭~~

CONTENT：

The story started a few years ago when Giorgio Vallortigara of the University of Trento, in Italy, and his colleagues, established that dogs wag their tails to the right when they see something pleasant, such as a beloved human master, and to the left when they see something unpleasant, such as an unfamiliar dominant dog. What Dr Vallortigara did not establish then was whether such signals are meaningful to other dogs. Now, he and the team from the previous study have done just that.

As they report in Current Biology, they wired up several dozen dogs of both sexes and various breeds with electrodes, to record the animals' heart rates, and then showed them videos of dogs, or silhouettes of dogs, head-on, with tail wagging to left or right. A left-wagging tail, they found, induced a higher maximum heart rate (in other words, an anxiety response) than a right-wagging tail, and this maximum heart rate lasted longer. A right-wagging tail, indeed, produced the same results as one that was stationary.

KEYWORDS:

electrode 電極

silhouettes 影子，輪廓