March 27, 2007 — Going right or left makes a big difference for tail wagging dogs, Italian researchers have discovered.
Tails wag to the right when dogs are happy and see something they want to approach, and to the left when they are frightened and confronted with something they want to run away from, claim the researchers.
According to Giorgio Vallortigara of the University of Trieste, Angelo Quaranta and Marcello Siniscalchi of Bari University, these "striking asymmetries in the control of tail movements" are another example of how the right and left halves of the brain control different emotions. They published their findings in a recent issue of the journal, Current Biology.
The researchers tested 30 family pet dogs — 15 males and 15 females with an age range of one to six years — in a large rectangular wooden box covered with black plastic to prevent dogs from seeing outside.
Vallortigara and colleagues filmed each dog's response to four different visual stimuli: the dog’s owner, an unknown person, a dominant, unfamiliar dog and a cat.
"When faced with their owner, dogs exhibited a striking right-sided bias in the amplitudes of tail wagging," the researchers wrote.
Tails kept wagging to the right when dogs were shown an unfamiliar person and the cat. The human stranger elicited less wagging than the owner, and the cat — a four-year-old European male placed in a small metal cage — the least wagging of all.
But when shown a large, unfamiliar and intimidating four-year-old male Belgian shepherd malinois — also kept in a cage — the tails leaned consistently leftwards.
