How well do dogs understand the owner's words? To verify it by measuring the brain

Recently CNN.co.jp reported the following:

犬は飼い主の言葉をどの程度理解している？　脳の測定で検証

2020.12.09 Wed posted at 11:00 JST

（ＣＮＮ） 犬は自分の言葉を全て理解してくれていると飼い主は思うかもしれないが、実は単語を逐一聞き取っているわけではない――。そんな調査結果が８日の学術誌に発表された。

犬は音声の解釈に関して「人間のような」聴覚能力を持っているものの、人間のように単語と単語の微妙な違いを聞き分けることはできないと研究チームは解説している。

ハンガリーのエトベシュ・ロラーンド大学の研究チームは飼い犬を使って実験を実施。犬の頭に電極を貼り付けて脳波を測定し、脳の活動を調べた。

実験では録音した音声を再生して、犬が覚えている「ｓｉｔ（お座り）」などの指示言葉と、「ｓｕｔ」のように発音が似ていて意味のない単語、さらには「ｂｅｐ」のように全く発音が異なる意味のない単語を聞かせて反応を調べた。

その結果、犬が覚えている指示言葉と、発音が全く異なる意味のない単語との違いははっきりと聞き分けられることが分かった。「犬が覚えている指示言葉を聞かせた時と、全く発音が異なる意味のない単語を聞かせた時では、脳の活動が異なる。つまり、犬はそうした単語を認識していた」と研究者は解説する。

しかし、発音が似ている意味のない単語との違いは認識せず、自分が覚えている指示言葉と同じ単語として処理していた。

「犬は発話された全ての音声に注意を払っているわけではなさそうだ」「普通の犬が一生のうちに学習できるのは、少数の指示言葉にとどまる」と研究者は解説する。

ただし、犬が本当に人間の言葉に耳を傾けていることや、聞いたことのない人の声にも反応することは確認できたとしている。

Translation

(CNN) A dog owner might think that the dog understood all his words, but in reality it didn't listen to each word. The results of such a survey were published in an academic journal on the 8th.

Although dogs had "human-like" hearing abilities in interpreting speech, a research team explained that dogs could not distinguish between words as humans do.

A research team at the University of Eötvös Loránd University in Hungary conducted experiments with their dogs. Electrodes were attached to the dog's head, and brain waves were measured to examine brain activity.

In the experiment, a recorded voice played back instruction words such as "sit" that the dog remembered, and meaningless words such as "sut" which had similar pronunciation; the dog even listened to words "bep" and the like that had completely different pronunciations and had no meaning so as to examine the reaction.

As a result, it was found that the difference between the demonstrative words that the dog remembered and those completely meaningless words that had different pronunciation could be clearly distinguished. The researchers explained that "dog's brain activity is different when hearing a word that it remembers comparing to hearing a nonsensical word that has a completely different pronunciation, which means that the dog recognizes those words" .

However, it did not recognize the meaningless words that had similar pronunciations, and treated them  the same as those instruction words it had remembered.

A researcher explained that the "Dog doesn't seem to pay attention to every voice spoken," and that "a normal dog can learn only a few directives in his lifetime".

However, he said that the study was able to confirm that a dog could really listen to human words, and respond to the voice a person that it had never heard of before.

              So, this study shows that dogs are not very good at understanding human voice precisely.