U.K. Artificial Intelligence Minister Kanishka Narayan leaves No. 10 Downing Street in London in July. | REUTERS

U.K. politicians looking to gauge how British voters will react to their policies have a new cohort on which to test their ideas: AI-generated focus groups.

Startups Electric Twin and Artificial Societies, and more established research firms GWI and Toluna are using data from real focus groups and surveys to build AI personas able to react to political messages within minutes. Another firm, London-based Synthetic Respondents, charges $16 (£12) a project, which it says is a thousandth of the cost of a traditional piece of focus group research.

Critics warn that reliance on AI-generated focus groups could detach politicians from reality.…