|Talks|

Rewarding Care: Defining the new frontier for mental health support

London Seminar Series
Hybrid
Past Talk
Ricardo Costa Dias Rei
Head of AI Research at Sword Health
Tue
,
Nov 17, 2026
10:00 am
EST
Nov 17, 2026
10:00 am
In-person
One Portsoken
714
Portsoken Street
London, E1 8PH, UK
The Roux Institute
Room
714
100 Fore Street
Portland, ME 04101
Network Science Institute
2nd floor
Network Science Institute
101 Belvidere Street
4th floor
Boston, MA 02115
Network Science Institute
2nd floor
One Portsoken
Room
714
58 St Katharine's Way
London E1W 1LP, UK
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Talk recording

One in eight people worldwide lives with a mental health condition, and many now turn to general-purpose chatbots for support. Yet a growing body of work shows these models fail consistently. They are sycophantic, validate unhealthy beliefs and foster dependency. We argue this is not a knowledge gap but an objective gap: the behaviours that make a conversation engaging are often the ones that make it clinically harmful. In this talk I will present our work to address this gap. First, I will show how modelling therapy as a sequence of counselling “moves” reveals that LLMs ask up to three times more questions than human counsellors while rarely explaining what is happening and why. I will then describe the instruments we built to measure care at scale: 1) a clinician-designed taxonomy of turn-level failures 2) a patient simulator whose conversations psychologists rate as far more realistic than earlier simulators. Next, I will cover MindGuard, our context-aware safety layer, and its validation with licensed clinicians. Finally, I will show how large-scale reinforcement learning inside a deployed, multi-agent environment produces a model that reduces sycophancy errors substantially. Real conversations then feed back into every component.
About the speaker
Ricardo Rei is Head of AI Research at Sword Health, where his team trains and evaluates language models for healthcare. Their recent work spans both machine learning and clinical venues, with papers accepted at NeurIPS and npj Digital Medicine. Before Sword, he was a Senior Research Scientist at Unbabel (acquired by TransPerfect), where he led the post-training of the Tower models and worked on EuroLLM, from pretraining data to evaluation. He was also the principal developer of COMET, a widely used metric for machine translation, and his PhD thesis received the EAMT Best European Thesis Award in 2024.
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