Wednesday, 19 December 2012

Is Timing an Important Feature of the Sounds Dogs Make?

We recently looked at the amazing story of how two dogs had been taught to go into an fMRI scanner – the beginnings of canine neuroscience. Today’s blog is about a study that takes a different, less hi-tech, approach to understanding the canine brain. Siniscalchi et al were interested in how dogs process other dogs’ vocalizations, and whether they show lateralization of the hemispheres – in other words, whether the left half and right half of the dog’s brain have different functions.

To begin with they needed to record some canine vocalizations. They took four dogs (two mixed-breed, one Border Collie, and one Rhodesian Ridgeback) and recorded the sounds they made during a disturbance, isolation, and play. To get the disturbance recording, they had the dog in a car with its owner, and a stranger approach. For the isolation recording, they got the sound the dog made when left on its own. And finally, the play sound came from a play session with a human. 

They then made a set of stimuli, one which involved the normal sound followed by silence, and the other which involved the sound played in reverse followed by silence. If temporal features – aspects to do with timing – are important, the dogs would respond differently to the signals played forwards and backwards.

Headshot of a rottweiler showing its brown eyes, ears and mouth
Photo: Ammit Jack / Shutterstock

Eighteen pet dogs of various breeds took part. They were tested in a room at the University, with their owner present. A feeding bowl was set up with speakers on either side, and the dog’s favourite dry food was placed in the bowl. While the dog was feeding, the different sounds were played through the speakers. The dog’s reaction was observed as a head-turn to the right or left, or no direction. Each dog was tested several times, each period lasting up to 30 minutes, and returned to the lab for additional sessions, until each sound (forwards and backwards) had been tested seven times.

The results showed that when played the normal vocalizations, dogs responded by turning their head to the right (right ear leading). This is thought to mean that the left hemisphere is activated. When the play signal was reversed, dogs turned their heads to the left (left ear leading), which is thought to mean that the right hemisphere is activated. When the isolation and disturbance sounds were played backwards, there was no significant effect, although there was a tendency to turn the head to the left. 

These differences suggest that temporal features of the sounds dogs make are important, as has been found with primate signals (and of course with human speech). The authors suggest that when the play signal is reversed it is completely novel, and that the right hemisphere is responsible for processing novel things. The play signal is a cooperative one, whereas the noises made during isolation and disturbance are made even if the dog is alone. They speculate that this is why they did not get a turn to the right for disturbance and isolation sounds; because the play signal is the most co-operative, it is probably more fixed in its pattern.

This study shows that temporal features of canine vocalizations are important, and also that the left hemisphere is involved in understanding other dogs’ communications. This adds support to the idea that the canine brain has specialization of the hemispheres.

Do you find it easy to understand the vocalizations that your dog makes?

Reference
Siniscalchi M, Lusito R, Sasso R, & Quaranta A (2012). Are temporal features crucial acoustic cues in dog vocal recognition? Animal cognition, 15 (5), 815-21 PMID: 22544303

1 comment:

  1. That's what my dog trainer is telling me. I'm actually learning more each day and I'm trying to form a special communication with my dog.

    ReplyDelete

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