Ewe look familiar

Researchers at the University of Cambridge have demonstrated that sheep have face-recognition abilities, comparable to those of humans and non-human primates.

Eight sheep were trained to recognise the faces of actors Jake Gyllenhaal and Emma Watson, former US President Barack Obama, and BBC newsreader Fiona Bruce. The sheep chose the familiar celebrity image over an unfamiliar face. They could also recognise the celebrity faces when they were presented in different perspectives, an ability previously only shown in humans.

Previous studies had shown that sheep could identify other sheep and human handlers that they already knew. But what the study’s lead author Jenny Morton asked was whether sheep could learn to recognise someone from a photograph.

She said that the team of researchers “focused on whether or not an animal was capable of processing a two-dimensional object as a person”.

Eight female Welsh Mountain sheep were shown different photos on two computer screens. The sheep made their choice by breaking an infrared beam with their noses to release a food pellet as a treat. The sheep were able to recognise the faces of the four celebrities 80% of the time.

The next stage was test whether the sheep could recognise the four celebrity faces if they were presented in different perspectives. This ability has previously been shown only in humans. Sheep successfully recognised the four celebrity faces from tilted images. While there was a drop in performance with the tilted images to 67%, this this a magnitude similar to that seen when humans perform the same task.

Finally, the researchers wanted to know if the sheep could recognise their handlers from a photo. Images of their custodians were randomly interspersed in a sequence of unfamiliar faces shown to them on the screens. The sheep were not pre-trained to recognise their handlers’ faces as they were with the celebrity faces, but the sheep were still successful, identifying their handlers 72% of the time. All good for the sheep, but why is this research useful to us? Researchers say it could help investigate cognitive dysfunction in humans.

Many diseases, such as Huntington’s and Parkinson’s, impair face perception, as do some psychiatric disorders such as autism spectrum disorder and schizophrenia.

Huntington’s disease has been modelled in sheep, but higher order behavioural and cognitive processes, such as face recognition, have not been tested in sheep with Huntington’s disease. The same face recognition experiment could be repeated on sheep with Huntington’s to study the cognitive decline associated with the disease.