Chapter 4Interlude: talk to ELIZA (1966)
Interlude: talk to ELIZA (1966)
ELIZA answered by matching keywords against rules a person wrote, not by predicting.1 It is famous, but it doesn't predict anything.
YOU your words→ look for a keyword→ apply a rule a person wroteELIZA a replyTalk to ELIZA in the Arcade →The 1966 chatbot that ran on keyword rules. Try it, then compare it with a model that predicts.
Joseph Weizenbaum wrote ELIZA at MIT between 1964 and 1966 on the IBM 7094 time-sharing system, in his own list-processing language, MAD-SLIP.21 He described it in "ELIZA—A Computer Program for the Study of Natural Language Communication Between Man and Machine" (Communications of the ACM 9, no. 1, January 1966).1 The program was general; its behavior came from a script, and the DOCTOR script, which imitates a Rogerian psychotherapist, became the famous one.12
People took to it quickly, and some confided in it as if it understood them.2 That reaction troubled Weizenbaum.2 In Computer Power and Human Reason (1976) he argued that some decisions should never be left to computers, whatever they can be made to do.2
Go deeper
The 1966 paper printed the DOCTOR script but not the program.13 A printout of Weizenbaum's original code was found in his papers at MIT in 2021 by Jeff Shrager and MIT archivist Myles Crowley,3 which is how we know, for example, that ELIZA also treated BUT as a delimiter and chose its MEMORY replies by a hash, not at random as the 1966 paper said.41 Sixty years on, ELIZA is usually called the first chatbot.3 For what changed between pattern matching and today's language models, see From Shannon's bits to Claude's tokens and the AI resources.
Notes (4)
- 1Joseph Weizenbaum, “ELIZA—A Computer Program for the Study of Natural Language Communication Between Man and Machine,” Communications of the ACM 9, no. 1 (January 1966): 36–45, https://doi.org/10.1145/365153.365168. Cited at pages 36, 37, 41, 44–45.
- 2Joseph Weizenbaum, Computer Power and Human Reason: From Judgment to Calculation (San Francisco: W. H. Freeman, 1976). Cited at pages 2, 3–5, 6–7, 7, 11–13.
- 3Rupert Lane, Anthony Hay, Arthur Schwarz, David M. Berry, and Jeff Shrager, “ELIZA Reanimated: The world's first chatbot restored on the world's first time sharing system” (preprint, arXiv, January 12, 2025), https://doi.org/10.48550/arXiv.2501.06707.
- 4Joseph Weizenbaum (transcribed by Anthony Hay, Arthur Schwarz, and Rupert Lane), “eliza.mad (transcription of the 1965 MAD-SLIP ELIZA printout),” eliza-ctss, 1965, https://raw.githubusercontent.com/rupertl/eliza-ctss/main/eliza/src/ELIZA/eliza.mad (accessed October 26, 2026).
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