Richard Clark via Getty Images
犬は、人間のことを理解する優れた力を持っている。人間が命令する声を理解できるし、何かを指差せばそれが何を意味しているかを、チンパンジー以上に理解できるという。また、最近は犬は人間の顔の表情まで読み取れるということも分かってきている。
そして今度は日本の研究者たちによって、「人間が犬をだまそうとすると犬にはそれがわかる」ということを示す新たな研究結果が発表された。
学術誌「Animal Congnition（動物認知）」オンライン版に2014年10月28日付けで発表されたこの論文の共著者で、京都大学大学院心理学研究室の非常勤講師、高岡祥子氏は、BBCに次のように語っている。
「犬には、一般に考えられているよりも優れた社会的知性があります。この犬の社会的知性は、人間とともに暮らしてきた長い歴史の中で、選択的に進化してきたものです」
この研究は、ペットとして飼われている34匹の犬を対象に、1人の人間が、おやつが入った食器と何も入っていない食器の両方を使って犬の反応を調べるという形で行われた。
実験の方法は次の通り。まず実験の第1段階で、人間がおやつの入った食器を指差す。これは犬にとって「良いアドバイス」だ。そして第2段階では、犬に両方の食器を犬に見せた後、今度は空の食器を指差す。その後第3段階で、第1段階とまったく同じように、再びおやつの入った食器を指差す、というものだ。
この実験の結果、第1段階と比べて第3段階では、犬たちが人の指差しに素直に従わない傾向が明らかに強かった。これは、人間が犬をだまそうとすると、犬はそれに気付いてその人をあまり信頼しすぎてはいけないと学ぶことを示唆している。
実験を行った研究グループは、論文の概要に次のように記している。「これらの結果が示すのは、犬が人間の指差しジェスチャーをよく理解する能力を持つだけでなく、指示を出す人間を信頼できるかどうかについても推測し、さらにそうした推測に応じて柔軟に行動を変えるということです」
犬をだまそうと考えるのは、あまり賢明なことではないかもしれない。
この記事はハフポストUS版に掲載されたものを翻訳しました。
[日本語版：水書健司/ガリレオ]
子犬たち
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NEW YORK, NY - JANUARY 30: Gibbs, a Golden Retriever puppy poses for pictures as the American Kennel Club Announces Most Popular Dogs in the U.S. on January 30, 2013 in New York City. (Photo by Gary Gershoff/Getty Images for the American Kennel Club) (credit:Getty Images)
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Puppies watch on at a police dog training base September 16, 2005 in Beijing, China. The dogs are trained by a police squad to learn identifying, catching, tracking and other skills. According to the Ministry of Public Security, there is an estimate of over 10,000 working police dogs in China. These dogs are divided into 30 kinds according to international conventions and are widely used in police work, rescue and military missions. (Photo by China Photos/Getty Images) (credit:Getty)
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A view of a puppy at the North Shore Animal League America\'s Tour For Life Pet Adoption Event on April 26, 2012 in New York, United States. (Photo by Cindy Ord/Getty Images) (credit:Getty)
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A view of a puppy at the North Shore Animal League America\'s Tour For Life Pet Adoption Event on April 26, 2012 in New York, United States. (Photo by Cindy Ord/Getty Images) (credit:Getty)
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A wolf plays with a one-month-old puppy in its enclosure of Berlin\'s Zoo on May 31, 2013 in Berlin. AFP PHOTO / JOHANNES EISELE (credit:Getty Images)
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Puppies just born by a sniffer dog sleep at a police dog training base September 16, 2005 in Beijing, China. The dogs are trained by a police squad to learn identifying, catching, tracking and other skills. According to the Ministry of Public Security, there is an estimate of over 10,000 working police dogs in China. These dogs are divided into 30 kinds according to international conventions and are widely used in police work, rescue and military missions. (Photo by China Photos/Getty Images) (credit:Getty)
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A Mastiff puppy rests during the XVIIIth International Dog exhibition on November 8, 2009 in Prague. (MICHAL CIZEK/AFP/Getty Images) (credit:Getty)
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A three-day-old Labradoodle puppy is shown to the press at the Uri Bekman\'s \'World of Dogs\' kennel in Pardesia, 30 kms north of Tel Aviv 07 December 2005. (YOAV LEMMER/AFP/Getty Images) (credit:Getty)
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Three-day-old Labradoodle puppies nap at the Uri Bekman\'s \'World of Dogs\' kennel in Pardesia, 30 kms north of Tel Aviv 07 December 2005. (YOAV LEMMER/AFP/Getty Images) (credit:Getty)
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A seven week old Daschund cross puppy waits to be re-homed at the Cheshire Dogs Home on January 4, 2010 in Warrington, England. (Photo by Christopher Furlong/Getty Images) (credit:Getty)
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Three-year-old Galia suckles her first litter of six puppies on June 4, 2009 at the Barry Foundation Great St. Bernard breeding kennels in Martigny, Western Switzerland. (FABRICE COFFRINI/AFP/Getty Images) (credit:Getty)
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Two-week-old puppies play on June 4, 2009 at the Barry Foundation Great St. Bernard breeding kennels in Martigny, Western Switzerland. (FABRICE COFFRINI/AFP/Getty Images) (credit:Getty)
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Two puppies play as American Kennel Club officials announce their annual list of the most popular dog breeds in the U.S January 27, 2010 in New York. (DON EMMERT/AFP/Getty Images) (credit:Getty)
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A volunteer holds up a puppy that was born after its mother has been rescued from a truck, in an animal hospital in Beijing, China, Tuesday, April 19, 2011. Chinese animal lovers mobilized by online calls for help blockaded a truck of hundreds of dogs being shipped off for food in a rare, permitted display of social action amid a broad crackdown on most kinds of activism. (AP Photo) (credit:AP)
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Nine Rhodesian Ridgeback puppies from a litter of 17 look out of their box in Nauen, 50 kilometers outside Berlin on Monday, Dec. 20, 2010. On Sept 28, and 29, 4 year old Ridgeback Etana had 17 puppies. All of them survived. (AP Photo/Markus Schreiber) (credit:AP)
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Seven Rhodesian Ridgeback puppies from a litter of 17 look out of their box in Nauen, 50 kilometers outside Berlin on Monday, Dec. 20, 2010. On Sept 28, and 29, the 4 years old Ridgeback Etana had 17 puppies. All of them survived. (AP Photo/Markus Schreiber) (credit:AP)
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A seven-week old Border Collie puppy rests after a play with its siblings in their garden as outdoors temperatures dropped below minus 10 degrees celsius in the village of Bodice on December 16, 2010. (JOE KLAMAR/AFP/Getty Images) (credit:Getty)
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Two adopted stray dogs play at an animal shelter on December 15, 2006 in the outskirts of Xian of Shaanxi Province, China. The animal shelter, established by Chinese animal lover Dai Shuqing, is located at an abandoned warehouse which houses some 100 dogs and costs over 2,000 yuan (about US $255) per month. (Photo by China Photos/Getty Images) (credit:Getty)
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Golden Retriever puppies with their handlers as the American Kennel Club officials announce their annual list of the most popular dog breeds in the U.S January 27, 2010 in New York. (DON EMMERT/AFP/Getty Images) (credit:Getty)
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