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Sheep recognize familiar and unfamiliar human faces from two-dimensional images.

Published version
Peer-reviewed

Type

Article

Change log

Authors

Knolle, Franziska 
Goncalves, Rita P 

Abstract

One of the most important human social skills is the ability to recognize faces. Humans recognize familiar faces easily, and can learn to identify unfamiliar faces from repeatedly presented images. Sheep are social animals that can recognize other sheep as well as familiar humans. Little is known, however, about their holistic face-processing abilities. In this study, we trained eight sheep (Ovis aries) to recognize the faces of four celebrities from photographic portraits displayed on computer screens. After training, the sheep chose the 'learned-familiar' faces rather than the unfamiliar faces significantly above chance. We then tested whether the sheep could recognize the four celebrity faces if they were presented in different perspectives. This ability has previously been shown only in humans. Sheep successfully recognized the four celebrity faces from tilted images. Interestingly, there was a drop in performance with the tilted images (from 79.22 ± 7.5% to 66.5 ± 4.1%) of a magnitude similar to that seen when humans perform this task. Finally, we asked whether sheep could recognize a very familiar handler from photographs. Sheep identified the handler in 71.8 ± 2.3% of the trials without pretraining. Together these data show that sheep have advanced face-recognition abilities, comparable with those of humans and non-human primates.

Description

Keywords

cognitive testing, learning, sheep

Journal Title

R Soc Open Sci

Conference Name

Journal ISSN

2054-5703
2054-5703

Volume Title

4

Publisher

The Royal Society
Sponsorship
CHDI Foundation, Inc (A2548)
Royal Society (unknown)
Royal Society (LT2009/JM/HL)
CHDI Foundation, Inc (A-4050)
CHDI Foundation, Inc (A-4050)