CAMBRIDGE, England — People who frequent their local petting zoo may not always remember every animal they visit, but it turns out the sheep may very well remember their visitors.
A new study, led by researchers at the University of Cambridge in the UK, tested the facial recognition skills of eight sheep, which were shown two-dimensional photographic portraits on a computer screen of four celebrities: actors Emma Watson and Jake Gyllenhaal, British journalist Fiona Bruce, and former U.S. President Barack Obama.
The researchers’ first experiment conditioned the woolly mammals to learn each celebrity’s face by serving them food after the star’s photo appeared on a screen. Later, the sheep were presented with two distinct photographs displayed on separate screens, with the animals using a custom pen to select the photo of the celebrity figure they’d learned.
Sheep were awarded with food for correctly choosing the picture of a famed individual; they lost out on a potential reward by selecting the other stock image.
Over time, this form of operant conditioning led the sheep to identify a human’s face with 80 percent accuracy, the researchers found.
A second experiment had the sheep complete a similar task under nearly identical conditions — the twist being that the faces of the subjects were presented at an angle. While the sheep’s performance fell by about 15 percent, this drop in accuracy mirrored that displayed by humans in similar facial recognition experiments.
Lastly, the researchers sought to see whether sheep could recognize their handlers, with whom they typically spent two hours a day, through a presented photograph. Without conditioning, the sheep chose the image of their handler over that of a random individual seven out of ten times.
During this experiment, sheep were observed doing a “double take” — checking both the unfamiliar face and the handler’s image, before selecting the latter.
“Anyone who has spent time working with sheep will know that they are intelligent, individual animals who are able to recognize their handlers,” says Jenny Morton, the study’s lead researcher, in a media release. “We’ve shown with our study that sheep have advanced face-recognition abilities, comparable with those of humans and monkeys.”
Morton notes that sheep typically live long lives, and have brains comparable to monkeys in terms of size and complexity.
She believes that future research could examine the potential for sheep’s brains to be used in understanding genetic cognitive disorders, such as Huntington’s disease.
Huntington’s disease, in specific, generally takes hold in adulthood, and is currently incurable.
The full study was published last week in the journal Royal Society: Open.