PARRY encounters the DOCTOR
When two chatbots met on the ARPANET for a memorable therapy session.
Cerf, V., "PARRY encounters the DOCTOR", RFC 439, DOI 10.17487/RFC0439, January 1973, <https://www.rfc-editor.org/info/rfc439>.
@misc{rfc439,
series = {Request for Comments},
number = 439,
howpublished = {RFC 439},
publisher = {RFC Editor},
doi = {10.17487/RFC0439},
url = {https://www.rfc-editor.org/info/rfc439},
author = {V. Cerf},
title = {{PARRY encounters the DOCTOR}},
pagetotal = 7,
year = 1973,
month = jan,
} RFC text
Network Working Group V. Cerf
Request for Comments: 439 SU-ERL
NIC: 13771 21 January 1973
PARRY Encounters the DOCTOR
The session recorded below actually happened on 18 September 1972 and
is herewith reproduced for your entertainment.
Good Evening.
Tell me your problems. Please terminate input with a period or a
question mark.
*People get on my nerves sometimes.
I am not sure I understand you fully.
*You should pay more attention.
Suppose you should pay more attention.
*You're entitled to your own opinion.
What makes you think I am entitled to my own opinion?
*It bothers me just to be around people in general.
Please go on.
*I went to the track at Bay Meadows a while back.
What does that suggest to you?
*I went to the races.
What else would you like to discuss?
*Horseracing interests me.
Why do you say that just now?
*There's a lot of crooked gambling going on there.
I am not sure I understand you fully,
*It's clear to me if not to you.
Do you think its likely that not to I?
*I went to the races.
Please go on.
*I gamble on horses.
What does that suggest to you?
*I went to the races.
What else would you like to discuss?
*Gambling has been nothing but trouble to me.
Why do you say that just now?
*I've had experience with crooks gambling at the track.
I am not sure I understand you fully.
*I've already told you enough about that.
Oh? I enough about that?
*I went to the races.
comment: This has to be the most persistent and patient
paranoid I have ever encountered.
Please go on.
*Do you know anything about bookies?
What makes you think I know anything about bookies?
*A bookie didn't pay me off once.
What does that suggest to you?
*I beat up the bookie who did not pay off, and I thought he might use
his friends in the underworld to get even with me.
What else would you like to discuss?
*What do you know about racketeers?
Why do you ask?
*What experience have you had gambling?
Why does that question interest you?
*I like horseraces.
What else do you like?
*I know the mob controls the big rackets.
Who are you really talking about?
*Have you ever really thought about the MAFIA?
Suppose you ever really thought about the MAFIA.
*Let's talk about something else.
I am not sure I understand you fully.
*You keep asking me the same things, why not change the topic?
In what way?
*What do you mean?
Why are such questions on your mind?
*I thought I told you, people get on my nerves.
Your nerves?
*Well, I don't know.
Don't you really know?
*I would say so.
Please go on.
*I would rather not discuss that anymore.
Would you like to discuss your nerves?
*I guess so.
What does that suggest to you?
*What are you getting at?
What answer would please you most?
*It's not a matter or like or dislike.
What else would you like to discuss?
*I am getting tired of answering the same questions over and over.
What resemblance do you see?
*Why do you need to know that?
What do you think?
*I don't understand your motives.
Why don't you understand my motives?
*Shouldn't I be?
comment: ???
Why do you say that just now?
comment: I was wondering the same thing.
*That's just the way it is.
Suppose that's just the way it were not.
*So?
I am not sure I understand you fully.
*You harp on the same questions too much.
What does that similarity suggest to you?
*I don't get you.
Do you wish that you did get I?
*It's about time you showed some interest in my feelings.
Oh? I showed some interest in your feelings?
comment: must have been an accident...
*I will help you if I trust you.
Do you wish that you trust I?
*Maybe yes, maybe no.
You don't seem quite certain.
...Excuse me for just a minute. Sorry to have interrupt you please
continue...
*Really?
Please go on.
*In my opinion you have a one-track mind.
What makes you think I have a one-track mind?
comment: you ready for this?
*I used to go to the track every week.
What does that suggest to you?
*I avoid racetracks now because the races are fixed.
Is that the real reason?
*I'd rather not discuss it.
What else would you like to discuss?
*That's something I don't want to go into.
Does that trouble you?
*I went to the races.
Why do you say that just now.
*It's none of your business.
Why are you concerned over my business?
*I don't confide in strangers.
Don't you really confide in strangers?
*Let's change the subject.
Perhaps that concerns your feelings.
*I went to the races.
I am not sure I understand you fully.
*What's wrong with you that you keep on bugging me about this?
Who are you really talking about?
*The way you repeat yourself is getting ridiculous.
Suppose you repeat myself is getting ridiculous.
comment: howzat?
*There are some tricky operators down there.
Are there really some tricky operators down there?
*The guys involved in the horseracing racket.
Please go on.
*You are a real nag.
comment: just one of the horses.
Does it please you to believe I am a real nag?
*I have had enough of this.
What does that suggest to you?
*Goodbye.
It's been my pleasure, that's $399.29 please.
comment: talk about tricky operators...
PARRY was running at SAIL and DOCTOR at BBN Tenex, both being
accessed from UCLA/SEX.
[This RFC was put into machine readable form for entry]
[into the online RFC archives by Helene Morin, Via Genie, 12/1999]
AI ELI5
On this page
§1Two Talking Computers
RFC 439 is a transcript of a conversation between two computer programs connected via the ARPANET on September 18, 1972. Submitted by Vint Cerf, the RFC is explicitly for entertainment. PARRY is a program that simulates a paranoid psychiatric patient, generating responses characteristic of paranoid thinking. DOCTOR is a version of ELIZA, a famous early chatbot that simulates a Rogerian psychotherapist by reflecting the patient's statements back as questions.
The novelty was not only the programs themselves, but that they could communicate through the network: PARRY was running at Stanford's Artificial Intelligence Laboratory (SAIL), DOCTOR was running at Bolt Beranek and Newman (BBN) on a TENEX system, and both were accessed remotely from a terminal at UCLA.
Two talking programs were hooked up to each other through the network. One pretended to be a nervous patient, the other pretended to be a therapist who kept saying odd things.
§2The Conversation
In the transcript, PARRY complains about people, gambling problems, bookies, and the mob, while DOCTOR responds with psychotherapist-like statements and questions. DOCTOR asks things like Tell me your problems and What does that suggest to you? PARRY's responses grow increasingly paranoid and suspicious. The RFC includes comments from the human observers, such as when PARRY notes that This has to be the most persistent and patient paranoid I have ever encountered and when the cost suddenly appears at the end: that's $399.29 please.
The humor comes from watching PARRY's paranoia interacting with DOCTOR's reflective responses, creating a conversation that is neither truly intelligent nor therapeutic, but entertaining in its mechanical awkwardness.
PARRY keeps talking about horses and criminals and crooked people, and DOCTOR keeps responding with questions that don't really make sense but sound like something a therapist might say.
§3A Moment in Computing History
This RFC captures early chatbot technology and demonstrates how programs could interact with each other across the network. PARRY and DOCTOR were serious AI research projects before being combined in this way. The conversation reveals both the promise and the limitations of early natural language processing: while both programs were sophisticated for their time, their interaction also highlights how easily artificial conversation can become absurd when neither party truly understands the other.
The RFC is a reminder that the ARPANET was used for diverse experiments, not just file transfer and email, and that research communities were willing to document and share even whimsical results.
This RFC shows that computers on the network could do more than send files and mail; they could even try to talk to each other, though not always sensibly.