Eliza — Joseph Weizenbaum (1966)

Jerz > Interactive Fiction

Eliza (Weizenbaum 1966) is the first chatterbot — a computer program that mimics human conversation. In only about 200 lines of computer code, Eliza models the behavior of a psychiatrist (or, more specifically, the “active listening” strategies of a touchy-feely 1960s Rogerian therapist).

Comment | Interaction | Transcripts | References


To interact with Eliza for yourself, visit Hayden’s java Eliza — “a complete and faithful implementation of the program described by Weizenbaum.” (The site requires the Java browser extension. You will probably see a warning message that asks permission to run a Java applet.)

There are scores of online Elizas. Some of them seem to modify Weizenbaum’s original code without any notice (I was ready to use one of these versions as a classroom demo, until it started making rude remarks and referred to recent events.


The program looks for simple grammatical structures and a small set of keywords, which include computers, family members, and emotions.

Fig. Eliza 1-1
How do you do. Please state your problem.
>> I spend too much time with computers.
Why do you mention computers ?
>> You are one.
Does it please you to believe I am one ?
>> Yes.
You seem to be quite positive.
>> I suppose I am.
How long have you been ?

The following transcript shows Eliza’s limitations fairly clearly. The program recognized the text “I am”, but proceeded as if the user had typed something like “I am happy.” Since there was no word following “I am”, Eliza’s response “How long have you been ?” makes little sense.

Fig. Eliza 1-2
How long have you been ?
>> 31 years.
I’m not sure I understand you fully.
>> Join the club.
Please go on.
>> You don’t make too much sense yourself.
We were discussing you — not me.
  • How effective was Eliza when it first appeared?Secretaries and nontechnical administrative staff thought the machine was a “real” therapist, and spent hours revealing their personal problems to the program. When Weizenbaum informed his secretary that he, of course, had access to the logs of all the conversations, she reacted with outrage at this invasion of her privacy. Weizenbaum was shocked by this and similar incidents to find that such a simple program could so easily deceive a naive user into revealing personal information. — Richard S. Wallace, “From Eliza to A.L.I.C.E.
  • Another amusing Eliza anecdote (firmly ensconced in computer folklore)



  • Weizenbaum, Joseph. “ELIZA – A Computer Program for the Study of Natural Language Communication between Man and Machine,” Communications of the Association for Computing Machinery 9 (1966): 36-45.
  • Weizenbaum, Joseph. Computer power and human reason. San Francisco, CA: W.H. Freeman, 1976.

See also: Kenneth Colby’s “Parry,” a simulation of a paranoid schizophrenic.

  • Colby, Kenneth M. et al. “Artificial paranoia.” Artificial Intelligence 2 (1972): 1-26.
  • Colby, Kenneth M. et al. “Turing-like undistinguishability tests for the validation of a computer simulation of paranoid processes.” Artificial Intelligence 3 (1973): 47-51.
  • ELIZA (Wikipedia)



Dennis G. Jerz
Jan 2000 — first posted
06 Mar 2001 — last updated
30 Oct 2006 — pruning and tweaking
04 Jun 2013 — minor reformatting



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