In 1966, MIT’s Joseph Weizenbaum published “ELIZA, a computer program for the study of natural language communication between man and machine” in Communications of the ACM. ELIZA carried on typed conversations using simple pattern matching and scripted responses; its best-known script, DOCTOR, imitated a Rogerian psychotherapist by reflecting users’ statements back as questions. Only the year of publication is documented, so this entry uses 1966-01-01.
Despite having no real understanding of language, ELIZA was strikingly convincing, and Weizenbaum observed that people readily attributed understanding and feelings to the program. This tendency to over-trust conversational software is sometimes called the ELIZA effect.
ELIZA is a landmark because it was one of the first programs to engage humans in natural-language dialogue and raised early questions about the illusion of machine understanding, questions that remain central in the era of modern chatbots.