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AI doesn't know 'no' – and that's a huge problem for medical bots

Many AI models fail to recognise negation words such as “no” and “not”, which means they can’t easily distinguish between medical images labelled as showing a disease and images labelled as not showing the disease

By Jeremy Hsu

19 May 2025

Medical MRI Scan on digital screen

AI models can struggle to understand the captions on some medical images

Getty Images

Toddlers may swiftly master the meaning of the word “no”, but many artificial intelligence models struggle to do so. They show a high fail rate when it comes to understanding commands that contain negation words such as “no” and “not”.

That could mean medical AI models failing to realise that there is a big difference between an X-ray image labelled as showing “signs of pneumonia” and one labelled as showing “no signs of pneumonia” – with potentially catastrophic consequences if physicians rely on AI…

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