IMPORTANT: Facial Action Coding is a complex routine that requires extra FACS training from a professional in that area.
Our examples will NOT make you a FACS professional. They only show how you can use INTERACT for Facial Action Coding.
Setting up a coding system that is easy to handle, but allows you to log various information for 59 Action Units in a natural way would be a challenge for regular INTERACT users, that is why INTERACT comes with some pre-defined implementations.
Using INTERACT and a clever combination of 'Prefix', 'Lexical-coding' and 'Lexical-chains', enables us to implement a Coding system covering all 59 action units with only 4 small Code definition files! (The full set is pre-installed, so you can test them and adapt them to your needs.)
Note: This approach focuses on Action Units only and allow for coding any combination of AUs.
It presumes that you want to enter the activity details for multiple Action Units within the same Event line.
The 'lines' can be manually logged durational Events, frame-by-frame time-stamp Events or a range of automatically created Time Sampling Events, with a fixed interval length.
Entering multiple Codes into the same Event, requires a separate Class column for each entry = a separate Class-column for each Action Unit.
We presume you are familiar with the basics of creating Time Sampling Events or manually logging Events with INTERACT, as well as with defining regular Code definition files.
This topic describes the contents of the example files, the way they are linked and the effect they have.
You can choose between an Intensity-only (No Modifier) setup or the full featured Intensity and Modifier setup.
This example describes the full featured Intensity + Modifier setup using all 59 Action Units.
Working with the No Modifier setup - included in your installation - works the same, there is just one level less to jump through.
In case of the Intensity + Modifier setup, the coding rhythm goes like this:
Action Unit - Intensity - Modifier - Action unit - Intensity - Modifier...
Note: Each Action Unit is identified by two digits on your keyboard, add a 0 in front of Action Units below 10.
Code definitions
The pre-installed FACS Codes are located under ..\Mangold INTERACT Data\CodeDefinitions\Demos\FACS.
The latest version described in this example can be downloaded here: www.videoanalysis.net/resources/interact/examples/FACS_CodeSetups.zip
IMPORTANT: All FACS Code definitions are designed to be used with the Coding Mode: Lexical (post-hoc).
You may skip the explanation that follows and just use the system, as described in the two most common implantation scenarios:
If you want to understand the way these Code Definitions are linked and why, read on right here.
1st FACS-Level
This file is used to identify the first digit of an Action Unit.
▪Open the 01_FACS_ActionUnit_Master.key file, within the Code definition window:
This start file (top-level) contains following information:
oA Key to enable the use of this file during a coding session.
oA Code that is not logged, because no Class is entered (the Code column could in fact be left empty, but this makes it easier to keep track of where you are during a coding session).
oThe column Lex.chain contains the name of the second level Code file, which contents enables you to create the second digit of your Action Unit class name.
oThe column Prefix contains the first digit of your Action Unit. This character is entered in front of the information found in the second level file. Together they build the number of an AU.
Because we need a separate column for each AU, but do not want to define all 59 AUs upfront, we use these Prefixes to build the Class descriptions on the fly:
A Prefix is always combined with the Class name on the following level. Existing Prefixes can be passed on to the next level using a +.
| TIP: | If you want to analyze faces in one-second-intervals, read Interval based FACS coding. |
▪Click in a line and click 
to open the next linked code definition file.
Note: Sub-level files are opened automatically during an observational session, the moment one of the Codes from the previous level is entered.
2nd FACS-Level
This file is used to specify the second digit of an Action Unit number:
This second-level file contains following information:
oA Key to enable the use of this file during a coding session, specifying the second digit of the Action Unit.
oThe Code column displays the second digit of your AU identifier.
oThe Class column is left empty, because the 'Code' should not be entered as a Code - it is only used for reference for entering the second digit of your AU-ID.
oThe Lex.chain column contains the name of the next (third-level) Code file, holding the Intensity Codes.
oThe Prefix column contains the second digit of the identified 'Action unit' Class name, so the AU-Class name can be built. The additional '+' in front of the actual prefix ensures that the first-digit-prefix is 'remembered' and passed on to the next (third level) Code file.
The '+' allows you to build a chain of prefixes!
Due to the two prefixes and the missing Class, you can create an AU-Class column called '36', by hitting [3] for the top-level and [6] in the second-level.
Note: Those 2 Code files do NOT contain any real Codes!
Just 'Prefix' entries to create separate columns for each Action Unit and a link to the next Code definition file under Lex.chain.
▪Click in a line and click to open the next linked code definition file.
3rd FACS-Level
This third-level Code file contains some 'real' Codes, to describe the Intensity of the identified 'action unit' and looks like this:
This file actually contains Codes and a Class to log our observations:
oThe Key column contains as always a [key] to identify a specific Code
oThe Code column now contains Codes that describe the 'Intensity' of the current 'Action unit' activity.
oThe Class column contains an "I" which is combined with the two AU digits from the collected Prefix information to form is the name of the 'Intensity' Class.
In combination with the previously collected Prefix information, this results in a Class column called '36I', which can hold the Intensity value for AU 36.
oThe link in Lex.chain leads us to the last Code definition file, containing the 'Modifier' information.
oWith the Prefix entry "+" we pass-on the already collected 'Prefix' Information ('36' in this example) to the next level.
▪Click in a line and click to open the next linked code definition file.
4th FACS-Level
The next Code definition file holding the 'Modifier'-Codes looking like this:
Like the previous 'Intensity' file, this 'Modifier' file contains several descriptive Codes and a Class "M" to collect the 'Modifier' Codes.
oThe Key column contains as always a [key] to identify a specific Code.
oThe Code column now contains Codes that describe the 'Modifier' of the current 'Action unit' activity.
oThe Class column contains an "M" which is combined with the two AU digits to form the name of the 'Modifier' Class.
In combination with the previously collected Prefix information, this results in a Class column called '36M', which can now hold the Modifier value for AU 36.
Note: If you do not need this 'Modifier' it is easy to adapt the setup or use the 'FACS-No Modifier' setup.
oThe Prefix column is empty because we are at the end of the first coding cycle and for the next AU new Prefix information is required.
oThe link in the Lex.chain column points to the top-level file again. This allows us to return to the first level Code file WITHOUT leaving the Event! This creates an infinite loop, allowing us to add more and more Action Units to the same Event.
Note: We cannot use the EOC check box here, because that would exit the Event!