ELIZA

A presentation by:Christopher Gregory Johnnidis

What is this ELIZA?• Computer program that has natural

langauge interactions with humans• Chatterbot: a bot program that attempts to maintain a

conversation with a human.• parodies a Rogerian therapist - essentially

an automated psychotherapist• Developed in 1966 by Joseph

Weizenbaum at MIT• Name is a reference to the myth of Pygmalion

How does Eliza work?1) Scans input sentences for keywords

• Keywords can have rank/precendence number• Commas/periods delimeters -> only single phrases

2) Analyzes input sentences according to transformation rules - decomposes sentence

keyword + transformation rule = script3) Responses generated based on

reassembly rules associated with the decomposition rules.

Technical Problems1. the identification of key words,2. the discovery of minimal context,3. the choice of appropriate transformation rules,4. generation of responses in the absence

of keywords, and5. the provision of an ending capacity for ELIZA

"scripts"

(Weizenbaum, 1966)

Illustrative example• ELIZA’s simple yet effective program

works as a sort of situational NLP because it does not have to have a large database filled with semantic meanings for a given context; ELIZA does not care about meaning.

• e.g. “I feel BLAH”• How long have you felt BLAH?

Why does Eliza work?• Doesn’t need a large knowledge

database

• Relies on suspension of disbelief

• and the assumption by the “patient” of implicit meaning in what ELIZA says

A real-life example• One Saturday morning about 9 a.m., a Vice President of Bolt,

Beranek, and Newman in charge of selling our Telcomp commercial service arrived at our PDP-1 computer room hoping to be able to use the computer for a demonstration. He found a note on the PDP-1 teletype that read: "TYPE ALL MESSAGES INTO THIS TELETYPE AND END THEM WITH A PERIOD." This note was left there by one of the programming bums who had just succedeed in making run a LISP version of the DOCTOR program (based on ELIZA as developed by Weizenbaum). However, the VP thought that this note indicated that this teletype was linked with the one in my home, since I often use the computer all night. Therefore, he started typing to "me," but in fact was typing to this version of the DOCTOR program. The following conversation ensued:

• (taken from SEHR, volume 4, issue 2: Constructions of the Mind)

real-life example• vp: Do you think that I can use the computer this morning?• eliza: Why do you ask?• vp: I might be able to make some additional Telcom sales.• eliza: Why aren't you so sure?• vp: My perspective customers have never seen a

demonstration of the system.• eliza: Does this mean very much to you?• vp: Of course it does.• eliza: You seem very positive about that.• vp: This is ridiculous.

real-life example• eliza: What do you mean, this is ridiculous?• vp: Is there any reason why I can't use the computer now?• eliza: Tell me more about your perspective customers.• vp: Please dial me up on 491-1850 • Note that after the last remark the VP did not obey instructions, and left

out the period. Therefore, of course, the computer didn't answer him. This so infuriated the VP, who thought I was playing games with him, that he called me up, woke me from a deep sleep, and said:

• vp: Why are you being so snotty to me?• bobrow: What do you mean I am being snotty to you? • The VP angrily read me the dialog that "we" had been having, and

couldn't get any response but laughter from me. It took a while to convince him it really was a computer.

My encounter with ELIZA

• yo, Eliza• Eliza? Hah! I would appreciate it if you would

continue.• wha?? anyway, i need your help • Is it because you need my help that you came

to me?• CLEARLY. so im presenting on you soon. can

you do something funny so I can show everyone?

My encounter with ELIZA

• Why do you say that? • oh dear• Can you elaborate on that?• ok, nevermind. youre a horrible listener• Earlier you said you need my help?• oh so you were listening...• Maybe your plans have something to do with this.• goodbye Eliza• My secretary will send you a bill.• as if!

Hmmm!• Clearly ELIZA has shortcomings

when you try to interact with it in a non-psychotherapy setting.

• Yet ELIZA still remains one of the most successful interactive programs of its time.

Eliza, meet Parry.• in 1972 Kenneth Colby created PARRY at Stanford

University, another chatterbot.• attempted to imitate a paranoid schizophrenic• Just as ELIZA takes advantage of the ability to

dodge questions, PARRY takes advantage of the ability to give seemingly outlandish responses.

• ELIZA was criticized for a lack of an internal world tracking; PARRY somewhat addressed this issue.

Questions??If so, ask ELIZA, because our time

is up.