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February 12, 2015

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Dogs can tell apart human facial expressions, study finds

Feb. 12, 2015
Courtesy of the University of Veterinary Medicine Vienna
and World Science staff

Dogs can tell apart dif­fer­ent hu­man fa­cial ex­pres­sions in pho­tographs, and ev­i­dence sug­gests they pre­fer to ap­proach “hap­py” rath­er than “an­gry” pho­tos, ac­cord­ing to a stu­dy.

Sci­en­tists pre­sented pho­tos of hap­py and an­gry wom­en’s faces side-by-side on a tou­ch screen to 20 dogs. Dur­ing a train­ing phase, dogs from one group were trained to tou­ch im­ages of hap­py faces. The oth­er group was re­warded for choos­ing an­gry faces.

Credit: Clever Dog Lab / Vetmeduni Vienna


To rule out that the an­i­mals were choos­ing based on ob­vi­ous dif­fer­ences be­tween the pic­tures, such as teeth or frown lines, the re­search­ers split the im­ages hor­i­zon­tally so that dur­ing the train­ing phase the dogs saw ei­ther only the eye ar­ea or only the mouth ar­ea. 

Most dogs learn­ed to tell apart the hap­py and an­gry halves, the re­search­ers said. They sub­se­quently al­so man­aged to iden­ti­fy the mood in new faces as well as in face halves that they had­n’t seen dur­ing the train­ing.

The find­ings were pub­lished Feb. 12 in the re­search jour­nal Cur­rent Bi­ol­o­gy.

Dogs trained to choose the hap­py faces mas­tered the task sig­nif­i­cantly faster than those who had to choose the an­gry faces, said study di­rec­tor Lud­wig Hu­ber, of the Messerli Re­search In­sti­tute in Vi­en­na, Aus­tria.

“It seems that dogs dis­like ap­proaching an­gry faces,” he added.

“We be­lieve that dogs draw on their mem­o­ry dur­ing this ex­er­cise. They rec­og­nize a fa­cial ex­pres­sion which they have al­ready stored,” added Corsin Müller of the in­sti­tute, one of the re­search­ers. “We sus­pect that dogs that have no ex­pe­ri­ence with peo­ple would per­form worse or could not solve the task at al­l.”

Dogs have a much bet­ter sense of smell and hear­ing than hu­mans, but the res­o­lu­tion of their vi­sion is about sev­en times low­er, the sci­en­tists ex­plained. “It had been un­known that dogs could rec­og­nize hu­man emo­tions in this way. To bet­ter un­der­stand the de­vel­op­ment of these skills, we want to per­form si­m­i­lar tests al­so with wolves,” said Hu­ber, whose team has spent the past three years in­ves­ti­gat­ing wheth­er dogs un­der­stand the emo­tions of peo­ple and oth­er dogs.


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Dogs can tell apart different human facial expressions in photographs, and evidence suggests they prefer to approach “happy” rather than “angry” photos, according to a study. Scientists presented photos of happy and angry women’s faces side-by-side on a touch screen to 20 dogs. During a training phase, dogs from one group were trained to touch images of happy faces. The other group was rewarded for choosing angry faces. To rule out that the animals were choosing based on obvious differences between the pictures, such as teeth or frown lines, the researchers split the images horizontally so that during the training phase the dogs saw either only the eye area or only the mouth area. Most dogs learned to tell apart the happy and angry halves, the researchers said. They subsequently also managed to identify the mood in new faces as well as in face halves that they hadn’t seen during the training. The findings were published Feb. 12 in the research journal Current Biology. Dogs trained to choose the happy faces mastered the task significantly faster than those who had to choose the angry faces, said study director Ludwig Huber, of the Messerli Research Institute in Vienna, Austria. “It seems that dogs dislike approaching angry faces,” he added. “We believe that dogs draw on their memory during this exercise. They recognize a facial expression which they have already stored,” added Corsin Müller of the institute, one of the researchers. “We suspect that dogs that have no experience with people would perform worse or could not solve the task at all.” Dogs have a much better sense of smell and hearing than humans, but the resolution of their vision is about seven times lower, the scientists explained. “It had been unknown that dogs could recognize human emotions in this way. To better understand the development of these skills, we want to perform similar tests also with wolves at the Wolf Science Center,” said Huber, whose team has spent the past three years investigating whether dogs understand the emotions of people or other dogs.