Cat Behaviour: What is CatFACS?

After gaining Facial Action Coding System (FACS) certification, a scientific system used to code and measure subtle facial movements in human behaviour research, I’m now studying CatFACS. If you’re wondering whether CatFACS is a coding system for cat behaviour, you guessed right, that’s exactly what it is! 

This article focuses on explaining CatFACS, which, like other animal FACS, has its foundations in human FACS, developed in the 1970s by Ekman and Friesen. To learn more about human FACS, check out this article: Behaviour Analysis: What is Facial Action Coding System (FACS)?

What is CatFACS?

CatFACS is a Cat Facial Action Coding System. Like human FACS and other animal FACS, CatFACS measures subtle facial movements, scientifically termed Action Units (AUs).

Action Units

Action units are unique anatomically based facial movements involving one or more muscles. Action units create distinct changes in the appearance of facial areas and work together (or on their own) to create facial expressions. Facial Action Coding Systems, human or animal based, do not measure expression. Instead, they focus on the smallest constituent components of expression–independent action units. 

Coding these small components, instead of combinations of action units, allows for research of facial movements unrelated to emotion, such as communication and pain signals. 

Since we don’t share a common language, animals (and some humans) cannot verbalise feelings such as pain. Therefore, recognising pain in animals is helpful to improve animal care and ethics, such as veterinary treatment and farming practices.

Animal FACS

There are similarities and differences across species in facial musculature and movements, hence FACS adaptations for different species. As well as human FACS, there are currently eight animal FACS:

• CatFACS (cats)

• DogFACS (domestic dogs)

• EquiFACS (domestic horses)

• OrangFACS (orangutans)

• ChimpFACS (common chimpanzees)

• MaqFACS (rhesus macaques)

• GibbonFACS (hylobatid species)

• CalliFACS (marmoset species)

These systems allow for comparison across species in communicative and emotional contexts, offering valuable insight into the differences and similarities between humans and animals.

If you’re interested in learning more or studying any of these, check out the AnimalFACS website, where you can freely access the manuals and tests.

FACS and CatFACS

Human FACS is considered the gold standard for facial movement analysis and has been used in scientific research for decades. Its development created a standardised system with a common descriptive language, providing a more objective methodology for measuring facial movement. The same methodology and language are used across all FACS systems.

Some action units are consistent across species, others are unique to the the species. For example, cats have whiskers and ear movements that humans don’t have. Cats also have a half blink (AU47) that humans don’t have, and both humans and cats display blinks (AU45/AU145) and eye closures (AU43/AU143). Believe it or not, cats, like humans, display a lip pucker (AU18/AU118). If you’re like me, you have cute imagery swimming around in your imagination right now.

Human FACS has led to fascinating research and discoveries. Research findings include facial movement patterns connected to emotion, deception, and medical and psychological disorders, for example, differences between suicidal and non-suicidal depressed patients. Its use is wide and varied and includes fields such as consumer research, behavioural science, computer graphics, animation, forensic science, neuroscience and social and clinical research.

Cats have 276 Expressions

Recently, new findings in cat expression research hit mainstream media, so you may have already heard that researchers have counted 276 expressions in cats. Researchers used CatFACS to code action units in expressions of 53 adult domestic shorthair cats. Twenty-six distinct action units made up the 276 expressions (action unit combinations). 

Expressions were sorted into two key categories–friendly and aggressive. Findings revealed the presence of eye closures during friendly interactions between cats, with ears and whiskers moving forward. Conversely, during aggressive encounters, ears were flattened and rotated (outwards), with constricted pupils.

The researchers also observed 139 expressions produced during playful interactions. Several action units associated with play behaviour were observed, including the lip corner puller, the movement occurring when humans smile, the lower lip depressor, lips part and jaw drop/mouth stretch. 

How CATFACS Works

Trained CatFACS coders study videos of cats within the context of the area of research, for example, communication, cognition and emotion. If you’re excited about the prospect of a new career studying cat faces (I get it!), don’t get too carried away. It’s not a full-time job, it’s usually researchers, their assistants and research students who do the coding.

Coders identify and document the presence of action units and action descriptors, occurring independently or in combinations. Unlike in human FACS, action units are not rated for intensity.

Like in human FACS, action units are divided into upper face (4 action units), lower face (12 action units, including whisker movements), action descriptors (7), head and eye movements (12), and gross behaviours (6). CatFACS also has ear action descriptors (7).

Studying CATFACS

CatFACS is available to study free of charge from the AnimalFACS website. However, it can seem complex to study if you are unfamiliar with action movements and facial expressions. I began studying CatFACS several years ago, while I was studying (human) FACS. I decided to leave CatFACS until I had mastered FACS, feeling I needed a solid foundation of FACS first. Now I’m certified as a FACS coder, I’ve re-started studying CatFACS and I’m ready to take the test. 

Human FACS is very complex, with a whopper of a manual and instructions for coding the intensity of action units. CatFACS seems easy in comparison, with a slim manual of six chapters. As mentioned, CatFACS does not code action unit intensity, hence the slimmer manual. That said, it’s not ‘easy’. It’s one thing to learn the action units and another to learn to spot these subtle movements on a video of a moving cat. 

The CatFACS Test

The test consists of 20 downloadable short videos of cats. You score whether each action unit is present (1) or not (0), inputting answers into a supplied scoresheet. Once complete, you email your scoresheet to AnimalFACS, where your results are compared to the scores of certified coders. Like with FACS, to pass, you need to gain a reliability score of .70 or higher (70% Agreement). If you don’t reach the 70% agreement mark, you receive feedback and can resubmit a test.

Why am I Studying CatFACS?

Understanding action units is important in my work, due to the association between these movements, emotion and communication, which is what my work is all about. I’ve done the hard graft in learning human FACS already; therefore, given I’m a crazy cat lady, it seems silly not to. I’m not sure whether I’ll ever need to use it, but it’s interesting to observe cat behaviours and to follow the science relating to the meaning or purpose of action units.

I’m considering learning more animal FACS after CatFACS because it’s interesting (and a bit quirky). I feel the more I learn and observe, the more I hone my skills for any behaviour observation, be it animal or human.

Any questions, let me know in the comments below.