The sheep were having two options in each step as a photo of celebrity face or another is of something else.
Humans and monkeys can now extend a warm welcome to sheep for joining us in being able to recognize human faces from photographs.
It's always been known a flock can become familiar with the visages of their human handlers.
Picking the celebrity earned a sheep a food-pellet reward.
The Cambridge congregation included eight Welsh Mountain female sheep that learned successfully four different faces of celebrities, during the experiment. Researchers from Cambridge's Department of Physiology, Development and Neuroscience trained eight sheep to recognise the faces of four celebrities from photographic portraits displayed on computer screens.
In fact, they could even recognise people when pictures were altered or were taken from a different angle, an ability only previously recorded in humans and primates.
Morton and her team are now studying sheep that have been genetically modified to carry the gene mutation that causes Huntington's disease. "Although I didn't think sheep could recognize emotion, it made me think about face recognition as a complex brain process". Then, during the trials, the sheep were released into a pen where they had to discern between the familiar faces and an object or an unfamiliar face.
Researchers consider facial recognition as one of the most important human social skills.
Scientists aim to use the sheep as models to understand disorders of the brain, such as Huntington's disease, that develop over a long time and affect cognitive abilities.
Jake Gyllenhaal, seen here with an animal that is not a sheep. When a portrait of the handler was interspersed randomly, the sheep chose them seven out of 10 times. 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.
The research's lead author Prof Jenny Morton said, "What we did is ask whether a sheep could learn to recognise someone from a photograph". Maybe they just didn't like that the non-familiar lacked a reward, for example.