44 Action Units.
One Complete
Picture.
EchoDepth Sport is built on the Facial Action Coding System (FACS) — the peer-reviewed standard for facial expression analysis developed by Paul Ekman and Wallace Friesen. Not a proprietary black box. Decades of published science.
What is FACS?
The Facial Action Coding System (FACS) is the world's most widely used and peer-reviewed method for measuring facial movement. Developed by psychologists Paul Ekman and Wallace Friesen in 1978 and refined through decades of published research, FACS defines 46 Action Units — the individual muscle movements that make up every human facial expression.
EchoDepth tracks 44 of those 46 Action Units in real time. Each AU is scored individually, then the patterns are cross-referenced against VAD emotional modelling to produce a comprehensive, scientifically grounded picture of each player's emotional state.
Unlike proprietary emotion detection approaches, FACS-based analysis is transparent, published, and peer-reviewed. When EchoDepth flags an AU deviation, you can trace exactly which muscle movement triggered it — and what the peer-reviewed literature says it indicates.
Developed
1978
Ekman & Friesen — University of California
Action Units defined
46
EchoDepth tracks 44 in real time
Academic citations
10,000+
Peer-reviewed publications referencing FACS
Industry standard
Yes
Used in clinical, research, and commercial contexts worldwide
VAD Emotional Modelling
The three-dimensional model that converts Action Unit patterns into interpretable emotional state.
V
Valence
The positive or negative quality of an emotional state. High valence = positive emotion. Low valence = negative emotion. Captures whether the player is in a constructive or destructive emotional space.
A
Arousal
The activation or energy level of an emotional state. High arousal = excited, alert, activated. Low arousal = suppressed, fatigued, disengaged. A primary fatigue and readiness marker.
D
Dominance
The degree of control, confidence, or agency in an emotional state. High dominance = in control. Low dominance = overwhelmed, anxious, lacking confidence. A pressure response indicator.
Key Action Units
A selection of the 44 Action Units tracked by EchoDepth Sport and their sport-relevant significance.
AU 1
Inner Brow Raise
Surprise, concern — distress indicator
AU 4
Brow Lowerer
Anger, concentration, neurological stress
AU 6
Cheek Raiser
Genuine happiness (Duchenne marker)
AU 7
Lid Tightener
Anger, intensity, focus arousal
AU 9
Nose Wrinkler
Disgust, contempt response
AU 12
Lip Corner Puller
Happiness — social vs genuine smile differentiation
AU 17
Chin Raiser
Doubt, uncertainty, emotional suppression
AU 20
Lip Stretcher
Fear, anxiety marker
AU 23
Lip Tightener
Anger, determination
AU 41/42
Lid Droop / Slit
Fatigue, neurological disruption — concussion marker
AU 43
Eyes Closed
Sleepiness, withdrawal, extreme fatigue
AU 45
Blink
Blink rate deviation — concussion and stress marker
EchoDepth Sport tracks 44 of the 46 FACS-defined Action Units. Full AU documentation available on request.
Science FAQs
Why FACS and not a proprietary emotion model?
FACS is peer-reviewed, transparent, and has over 40 years of published validation. Proprietary models are black boxes — you cannot interrogate why they produce a given output. FACS-based analysis is auditable, explainable, and defensible in welfare and medical contexts where that matters.
How many Action Units does EchoDepth Sport track?
EchoDepth Sport tracks 44 of the 46 Action Units defined in the FACS standard.
Is FACS used in clinical and medical settings?
Yes. FACS is used in clinical psychology, pain assessment, neuroscience research, and neurological condition monitoring. Its use in concussion protocol support builds on an established medical research base.
What peer-reviewed research underpins EchoDepth Sport?
EchoDepth Sport's scientific foundation draws on 8 peer-reviewed research papers covering facial AU analysis, VAD modelling, and sport-specific emotional performance research. Full citations are available on request.