Beyond Polygraph.
Beyond EyeDetect.
Polygraph measures anxiety with physical sensors attached to the body. EyeDetect measures one channel — the pupil. Neither reads the 44 involuntary facial Action Units that four decades of FACS research have correlated with deception, stress, and suppression. EchoDepth reads all of them.
EchoDepth by Cavefish AI Ltd · Cardiff, Wales · Camera-based emotion recognition AI
Why do polygraph and EyeDetect have fundamental limitations?
Polygraph was built in 1939. Its scientific basis was formally disputed by the National Academy of Sciences in 2003, which found it lacks scientific validity for security screening. UK courts do not admit polygraph evidence. Yet it remains the default — not because it works, but because no credible replacement has reached procurement.
EyeDetect is the most credible commercial alternative — and it measures one channel: pupil dilation. That is one of 44 involuntary facial signals documented in the Facial Action Coding System. Measuring only the pupil leaves a substantial body of peer-reviewed signal completely unread.
// US DOD · Defense Innovation Unit · 2023
"Advancements in standoff physiology sensing using cameras have the potential to be less intrusive and more reliable than existing methods." EchoDepth is built to that specification.
Structured analytical output.
Not a verdict. A defensible evidence layer.
- Per-question stress and arousal mapping — emotional state timestamped to each question moment during a structured interview
- AU activation log — which of the 44 FACS-compliant Action Units fired, at what intensity, at what moment
- Temporal anomaly detection — deviation from the subject's own established baseline, not population averages
- Structured report export formatted for interview case files, legal review, or intelligence reporting chains
- Live interview overlay — optional real-time display for the interviewer, not visible to the subject
- Standard camera operation — no IR kiosk, no physical attachment, no specialist hardware required
- UK data residency and full air-gap deployment for STRAP and above environments
"EchoDepth does not claim to detect lies. No technology reliably detects lies. EchoDepth detects the involuntary physiological markers — across 44 FACS-coded Action Units — that accompany deception attempts. The determination of credibility remains with the human analyst."
| Capability | Polygraph | EyeDetect | Clearspeed | EchoDepth |
|---|---|---|---|---|
| Contact | Physical sensors + examiner | IR kiosk | Phone/web | ✓Camera only |
| Continuous | Session only | Session only | Session only | ✓24/7 passive |
| Signal channels | Cardio/GSR/breath | Eyes only | Voice only | ✓44 FACS Action Units |
| Science basis | Disputed NAS 2003 | Limited replication | Proprietary | ✓FACS peer-reviewed |
| UK admissibility | Inadmissible | Not established | Not established | ✓Timestamped audit |
| API integration | None | None | Limited | ✓REST/WebSocket/SIEM |
| Air-gap deploy | N/A | Not offered | Cloud-only | ✓Full on-premise |
| UK data residency | Examiner-held | US-hosted cloud | Partial | ✓UK standard |
Frequently Asked
How does EchoDepth differ from polygraph? +
Polygraph measures physiological responses via physical sensors attached to the body — heart rate, respiration, skin conductance. EchoDepth analyses 44 FACS-compliant facial Action Units using a standard camera. No contact, no specialist hardware. UK courts do not admit polygraph evidence; EchoDepth produces structured, timestamped analytical output designed for evidential use and integration into case management systems.
How does EchoDepth compare to EyeDetect? +
EyeDetect (Converus) measures pupil dilation and eye movement — one signal channel based on cognitive load theory. EchoDepth analyses 44 facial Action Units across the full FACS system. EchoDepth also supports continuous monitoring, API integration into existing security platforms, and UK on-premise deployment. EyeDetect requires a dedicated IR hardware kiosk; EchoDepth operates on standard cameras already installed in your environment.
Does EchoDepth detect lies? +
No — and any system that claims to reliably detect lies should be treated with scepticism. EchoDepth detects involuntary physiological markers across 44 FACS-coded Action Units that are correlated with deception attempts, stress, and cognitive suppression. Output is structured analytical data to support trained interviewer judgement. The determination of credibility remains with the human analyst.
Is EchoDepth suitable for UK intelligence and government use? +
Yes. EchoDepth offers full on-premise and air-gapped deployment for classified environments, UK data residency as standard, and role-based access controls compliant with UK GDPR and the HMG Security Policy Framework. The system is designed to operate within existing security infrastructure — not alongside it as a standalone tool.
Is EchoDepth admissible as evidence in UK courts? +
EchoDepth is not positioned as standalone evidence. It provides timestamped, structured analytical output — per-question emotional variance records — that can form part of an evidential picture alongside other investigative material. Unlike polygraph, which is inadmissible in UK criminal proceedings, EchoDepth's output is designed with audit-trail and legal review requirements in mind.
See What Your Security Stack Is Missing.
Structured technical briefings for defence procurement, security leadership, and intelligence teams. NDA available. Air-gapped demo environment on request.
DEFENCE@CAVEFISH.CO.UK · CARDIFF, WALES · UK DATA RESIDENCY STANDARD