Those whose pet dog has mastered the word “ball” will probably notice that their pet’s ear sounds have risen to sounds like “hall” and “fall”. This is because dogs are unable to process all the phonetic details of our speech, and therefore are unable to distinguish highly similar words, according to a new study in the Royal Society’s Open Science Journal. This, researchers say, is why most dogs manage to learn only a small number of commands.
Exactly how ugly the dog is to the various phonetic elements of human conversation has been the subject of much debate over the years. For example, a 2005 study found that quinines trained to obey the “come” and “sit” commands were more likely to be hesitant if they misinterpreted these commands by changing the first letter or tone.
To address the issue, the team behind this latest study tried to determine how the various components that make up a sound are processed by the dog’s brain. They tapped the electrodes on the heads of 17 pet dogs and monitored their brain activity as they listened to their owners ’voice recordings. During the test – which was conducted at Loránd University in Eötvös, Hungary – the dogs heard two commands with four signatures (in Hungarian), as well as similar but irrational words in which one vowel or letter changed and completely different nonsense words that did not resemble the original word.
Using electroencephalography (EEG), the researchers found that dogs were able to instantly distinguish between real commands and bad words. This was confirmed by the fact that these two types of utterances marked highly brain signals – known as event-related potentials (ERPs) – as fast as 200 milliseconds after the onset of these auditory stimuli.
Patterns of activity of these mirrors are commonly seen in the adult human brains that respond differently to regular and noisy sounds within the first few hundred milliseconds. More interestingly, when dogs hear nonsense other than pure words by single speech elements, their brains respond in the same way as true commands. In other words, the dog’s brain was unable to detect subtle differences between highly similar sounds.
According to the authors, this kind of word processing ability is similar to that of human children, who become proficient in distinguishing between the phonetic elements of speech during the second year of their lives. “Similarly in the case of human children, we hypothesize that similar similarities and similar nonsense to the sounds of instructions they know with the brain activity of dogs reflect not perceptual impediments but concentration and processing biases,” study author Attila Andics explained in a statement. “Dogs cannot participate in all the details of speech sounds when they hear words. Further research may reveal that this may be a factor that disables dogs from acquiring a vast vocabulary.”