FACS stands for Facial Action Coding System and is used to code facial expressions based on muscle movement.
The Facial Action Coding System (FACS) and it's Action Units are based on the book of Carl-Herman Hjortsjö "Man's Face and Mimic Language" (Swedish version: “Människans ansikte och mimiska språket”, 1969: Malmö, Studentlitteratur).
Hjortsjö was professor of Anatomy at Lund University in Sweden.
The system introduced in this book was substantially developed further by Paul Ekman and Wallace Friesen who published the FACS-system as we know it in 1978.
The Facial Action Coding System dissects facial expressions into 56 "Action Units" (AU's), which are used to describe the contraction or relaxation of one or more muscles. It enables researcher to taxonomies every conceivable human facial expression.
It is still the most popular standard used to systematically categorize the physical expression of emotions. FACS is used in psychology as well as anatomy
ohttps://www.paulekman.com/product-category/facs/
ohttps://en.wikipedia.org/wiki/Facial_Action_Coding_System
IMPORTANT:Coding facial expressions is a very complex research area, with a sheer endless number of combinations for 'action units', 'modifiers' and 'levels of 'intensity' in one way or another.
We do NOT offer any FACS training, we can only assist you with the implementation of the required coding system based on your preferred approach.
INTERACT offers some pre-installed examples of possible Codes for coding facial expressions in the directory ..\Mangold INTERACT Data\CodeDefinitions\Demo\FACS.
How to code Facial Expressions with INTERACT
The sample setups include systems for the following approaches:
 | Log multiple Action Units (AUs) per video frame - This setup presumes you want to observe every single video frame and be able to add the activity for multiple AUs to each frame. - Read Log 1-Frame FACS Events |
| Log multiple action units (AUs) per individual Event - If you want to create individual Events for a specific activity and enter all AUs that were used into that Event, take a look at this example. |
| Log multiple action units (AUs) per predefined interval - This setup presumes you want to observe predefined, fix intervals and need to add multiple AUs to each interval. |
| Log separate Events per action unit - To log individual Events per AU, creting overlapping Events for those AUs that show activity (partly) simultaneous. |
Find out how and why those Code definitions are defined like they are and which approach suits you best!
Because the way of coding is influenced a lot by personal habits, preferenses and research goals, you probably need to adapt the Code files to change the coding rhythm to your way of working.
If you have trouble implementing your favorite coding system or achieving your preferred coding rhythm, please feel free to contact us!