What is CatFACS?

The Cat Facial Action Coding System (CatFACS) is a scientific observational tool for identifying and coding facial movements in cats. The system is based on the facial anatomy of cats and has been adapted from the original FACS system used for humans created by Ekman and Friesen (1978). The CatFACS manual details how to use the system and code the facial movements of cats objectively. The manual is freely available to the scientific community.


CatFACS is a standardized system that requires certification to use. The CatFACS Manual identifies each muscle movement that causes visible changes in facial appearance. These are called Action Units (AUs) and each AU is listed in the manual with a numerical code. For each AU, the muscular basis is described along with a list of observable appearance changes and subtle differences between AUs.


The CatFACS Manual and the CatFACS Test are freely available through this website. Please contact us for the passwords. We keep a record of who is using the system so we can maintain standardisation.


For a correct visualization of the CatFACS Manual, please install the latest version of Adobe Reader on your computer. To decompress the files (manual and test), please install WinRar.


Click here to download the CatFACS manual.


To use the system you need to take a test after training. This ensures that all users are coding in the same way, and maintains the standardisation of the system.


To access the CatFACS Test clips click here.

Please notice that you can attempt the CatFACS Test several times if you don't pass initially. For each additional attempt, however, you may need to wait for several weeks to receive your scores, especially during busy periods. It is also important that the trainee takes enough time to revise the Manual before a second attempt.

How to use it?

After becoming CatFACS certified, the coder will be able to reliably code facial movements in videos and pictures of cats. High quality close-ups of the face should ideally be recorded and pictures must be compared with the neutral face of each cat, accounting for individual variation. Depending on the purpose of coding, two or more cameras should be used in synchrony (e.g. one camera zoomed in on the face and other camera recording body and context behaviours).


The CatFACS can be applied to investigate communication and emotion in cats through the analyses of the individual facial behaviour.

The people behind it

CatFACS was developed thanks to the joint effort of:

  • Cátia Caeiro, School of Psychology, University of Lincoln, UK
  • Bridget M. Waller, Centre for Comparative and Evolutionary Psychology, University of Portsmouth
  • Anne Burrows, Duquesne University and University of Pittsburgh


This work was supported by a Feline Friends Research Donation to Bridget Waller.


We would like to thank the following people that contributed to the CatFACS manual production:

  • Daniel Mills for establishing a collaboration between University of Lincoln and University of Portsmouth for the project development.
  • Catarina Ferreira, Daniel Mills, Lauren Finka, Sarah Ellis and Will Higgs ( for the videos and photographs contributions.
  • Inês Martins for drawing the anatomical images.
  • Alison, Andrea Karis, April Turgutalp, Brusspup, Chester Smooshyface, Heliflyer7, Joe Martin, Katia Shifrin (k_shifrin(at)yahoo(dot)com,, Kevin Christensen, Larry Graves (, Laura Palmer & Wintermuse, llrnr, Molly Barr of Mythicbells Persian cats and kittens, Patrizia Piotti, Saffy, Hector & Millie, Sean Coonery (, Sijimi_soupzz,,,, for permission to use their clips from
  • Jennifer Wathan for the reliability assessment coding.
  • And finally, to Daniel Mills and Jennifer Wathan for helpful comments on previous versions of this manual.

Contact us

Psychology Department

University of Portsmouth

Portsmouth, UK

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