Of the roughly 1.1 billion sheep on Earth, roughly 1.1 billion have no idea who Barack Obama is. These sheep have learned to select the portrait of former president out of a set of pictures.
Recognizing Obama meant the sheep won a snack. The scientists have been rewarded better for measuring the brain functions of sheep.
Morton and her team are now studying sheep that have been genetically modified to carry the gene mutation that causes Huntington's disease. Seven years ago, she said, she bought these sheep out of the back of a truck on its way to a slaughterhouse. This convinced the researchers that sheep had face-recognition abilities similar to ours.
These woolly creatures grasped this recognition skill after going through three scenarios of training. After training, the sheep were shown two photographs - the celebrity's face and another face.
The sheep would nuzzle up close to their chosen screen, where they would trigger an infrared sensor releasing a treat, if they had chosen correctly. First, the team familiarized the sheep with the celebrities' faces by showing the faces opposite a black screen or random objects. The second round was slightly more challenging.
"We chose the celebrities nearly randomly", Morton said, as long as there were lots photos to choose from.
"We also chose them because we were sure that our sheep had never met them in person!".
The sheep made the correct choice of celebrity or handler roughly 70 percent of the time on average. In these initial tests, the sheep were shown the faces from the front, but to test how well they recognised the faces, the researchers next showed them the faces at an angle.
Sheep can be trained to recognize faces of celebrities, a Cambridge University study found. "This current study adds an interesting new ability to the surprising wide repertoire of behaviour of sheep". In these trials, though, the celebrity's heads were tilted, beagle-like, at unfamiliar angles. People recognise familiar faces easily, and can identify unfamiliar faces from repeatedly presented images. Their success rate decreased by 15 percent. And you thought you were so special, human.
Along with dogs and monkeys, sheep are social animals that can recognize other sheep as well as familiar people, the study authors explained.
A sheep "model" of Huntington's disease has been bred, displaying similar brain and social changes as witnessed in human patients. Recently, scientists created genetically modified sheep that have Huntington's. "I suspect they do have a genuine sense of the identity", he said. "That says to me that identity is important". Over time, they learn to associate a reward with the celebrity's photograph. "But the evidence is compelling", Morton said.
The study feeds into ongoing research on treating neurodegenerative diseases such as Huntington's, in which face perception can be impaired. Perhaps a test like this could help study these sheep's "cognitive decline".