Guides
What the body can tell you, what HRV can't, and what the law now says about faces and voices.
Every claim on these pages is cited.
Why would heart rate tell you anything about the brain?
The oxytocin → vagus nerve → cardiac rhythm mechanism, with citations.
ReadHeart rate vs HRV vs Immersion
What each metric can and can’t tell you, with five worked moments.
ReadHow do I measure emotion in my app?
Five ways to do it. Four make you liable for something. One doesn’t.
Read- Immersion vs facial codingBiometric identifier plus emotion recognition.
- Immersion vs voice prosodyVoiceprint plus emotion recognition.
- Immersion vs HRVHealth data plus emotion recognition, without the science.
- Immersion vs surveysLawful, simple, and late.
- Developer FAQShort answers to measurement, regulation, platform, and billing questions.
- GlossaryValue, Psychological Safety, prediction engine, MAU, and the rest, defined once.