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What is the Cavefish Emotional Index (CEI)?
The Cavefish Emotional Index (CEI) is a 0 to 100 score of how people feel, read directly from what they write or say. It is the average of five readings, each scored 0 to 100 where higher is healthier: Advocacy, Goodwill, Engagement, Drive and Assurance. The result is reported in four bands: Strong (80 and above), Good (60 to 79), Watch (40 to 59) and Act (below 40). Because it reads people's own words rather than a rating question, the CEI works for customers, colleagues and audiences on one scale, and every EchoDepth product uses the same readings and bands. In an EchoDepth ad test, the CEI is read from what viewers write or say after watching. It is not the facial coding measure: that is the Emotional Response Curve, built second by second from facial movement. The CEI is sometimes written as the Cavefish Emotion Index.
Updated 19 October 2026 by Jonathan Prescott, Founder, Cavefish. Canonical definition: cavefish.ai.
The five readings behind the CEI
Each response is read for its emotional content and placed on five scales, each 0 to 100 with higher healthier. The CEI is their average across everyone.
| Reading | What it asks of what people said |
|---|---|
| Advocacy | Do they have anything good to pass on? |
| Goodwill | How much hostility is in what they said? Higher means less. |
| Engagement | Are they still invested, or have they resigned themselves to it? |
| Drive | Are they still trying to fix it themselves? |
| Assurance | Do they know where they stand? Higher means less unease. |
The four bands
| Band | CEI |
|---|---|
| Strong | 80 and above |
| Good | 60 to 79 |
| Watch | 40 to 59 |
| Act | Below 40 |
The bands are the same in every EchoDepth module, so a Good score means the same thing in an ad test as anywhere else.
The CEI in an ad test
An EchoDepth ad test produces two separate measures. The Emotional Response Curve is what viewers' faces did: valence, arousal and dominance derived from 44 FACS Action Units on every frame, averaged across viewers and plotted second by second. The CEI is what viewers said: their open answers and spoken comments after watching, scored on the five readings.
The report sets one against the other. When the curve peaks but the CEI is low, people responded in the moment but did not carry it into what they said. When the CEI is high but the curve is flat, people are saying the right things about an ad that did not move them. How the curve is built is set out in the methodology.
CEI vs Net Promoter Score
Net Promoter Score asks one question, how likely you are to recommend something from 0 to 10, and reports the percentage of promoters minus the percentage of detractors. Someone who answers 4 counts the same as someone who answers 0. The CEI reads what people said in their own words, so it can separate someone who is angry but still invested from someone who has quietly given up. Cavefish's full comparison is at CEI vs NPS.
One scale across EchoDepth
Cavefish built the CEI so the same reading works wherever people write or speak: customer comments, colleague feedback and audience reactions. On this site it is used for ad and creative testing. For other ways of scoring emotion, and how vendors build them, see what is an emotional engagement score?
Is it the Cavefish Emotion Index or the Cavefish Emotional Index?
The name is the Cavefish Emotional Index, abbreviated CEI. It is sometimes written as the Cavefish Emotion Index; both refer to the same 0 to 100 score.
Is the CEI an employee survey score?
No. The CEI reads what people write or say, so it works for customers, colleagues and audiences alike. Every EchoDepth product uses the same scale and bands, from employee research to ad testing.
Is the CEI the same as the facial coding score in an ad test?
No. In an EchoDepth ad test the facial measure is the Emotional Response Curve, built second by second from 44 FACS Action Units. The CEI is read from what viewers write or say after watching. Setting one against the other shows whether what people said matches what their faces did.
How is the CEI different from Net Promoter Score?
NPS asks one question and keeps only which of three buckets each person fell into. The CEI reads what people said in their own words, scores five readings and reports a 0 to 100 index in four bands, so it can separate someone who is angry but still invested from someone who has given up.
Where is the CEI defined?
The canonical definition is published by Cavefish at cavefish.ai/compare/cei-vs-nps. EchoDepth uses that definition in every module.