Chatbots are now everywhere. You seemingly can’t touch a computer without one offering its opinion, or trying to help. This explosion is a result of the advent of what are called Large Language Models: sophisticated programs that in part copy the way human brains work. Chatbots have been around far longer than the current boom, though. The earliest successful one, called ELIZA, was, built in the 1960s by Joseph Weizenbaum, who with his Jewish family had fled Nazi Germany in the 1930s. Despite its simplicity ELIZA was very effective at fooling people into treating it as if it were a human.
Weizenbaum was interested in human-computer interaction, and whether it could be done in a more human-like way than just by typing rigid commands as was done at the time. In doing so he set the ball rolling for a whole new metaphor for interacting with computers, distinct from typing commands or pointing and clicking on a desktop. It raised the possibility that one day we could control computers by having conversations with them, a possibility that is now a reality.
His program, ELIZA, was named after the character in the play Pygmalion and musical My Fair Lady. That Eliza was a working class women who was taught to speak with a posh accent gradually improving her speech, and part of the idea of ELIZA was that it could gradually improve based on its interactions. At core though it was doing something very simple. It just looked for known words in the things the human typed and then output a sentence triggered by that keyword, such as a transformation of the original sentence. For example, if the person typed “I’m really unhappy”, it might respond “Why are you unhappy?”.
In this way it was just doing a more sophisticated version of the earliest “creative” writing program – Christopher Strachey’s Love Letter writing program. Strachey’s program wrote love letters by randomly picking keywords and putting them into a set of randomly chosen templates to construct a series of sentences.
The keywords that ELIZA looked for were built into its script written by the programmer and each allocated a score. It found all the keywords in the person’s sentence but used the one allocated the highest score. Words like “I” had a high score so were likely to be picked if present. A sentence starting “I am …” can be transformed into a response “Why are you …?” as in the example above. to make this seem realistic, the program needed to have a variety of different templates to provide enough variety of responses, though. To create the response, ELIZA broke down the sentence typed into component parts, picked out the useful parts of it and then built up a new response. In the above example, it would have pulled out the adjective, “happy” to use in its output with the template part “Why are you …”, for example.
If no keyword was found, so ELIZA had no rule to apply, it could fall back on a memory mechanism where it stored details of the past statements typed by the person. This allowed it to go back to an earlier thing the person had said and use that instead. It just moved on to the next highest scoring keyword from the previous sentence and built a response based on that.
ELIZA came with different “characters” that could be loaded in to it with different keywords and templates of how to respond. The reason ELIZA gained so much fame was due to its DOCTOR script. It was written to behave like a psychotherapist. In particular, it was based on the ideas of psychologist Carl Rogers who developed “person-centred therapy”, where a therapist, for example, echos back things that the person says, always asking open-ended questions (never yes/no ones) to get the patient talking. (Good job interviewers do a similar thing!) The advantage of it “pretending” to be a psychotherapist like this is that it did not need to be based on a knowledge bank of facts to seem realistic. Compare that with say a chatbot that aims to have conversations about Liverpool Football Club. To be engaging it would need to know a lot about the club (or if not appear evasive). If the person asked it “Who do you think the greatest Liverpool manager was?” then it would need to know the names of some former Liverpool managers! But then you might want to talk about strikers or specific games or … A chatbot aiming to have conversations about any topic the person comes up with convincingly needs facts about everything! That is what modern chatbots do have: provided by them sucking up and organising information from the web, for example. As a psychotherapist, DOCTOR never had to come up with answers, and echoing back the things the person said, or asking open-ended questions, was entirely natural in this context and even made ti seem as though it cared about what the people were saying.
Because Eliza did come across as being empathic in this way, the early people it was trialled on were very happy to talk to it in an uninhibited way. Weizenbaum’s secretary even asked him to leave while she chatted with it, as she was telling it things she would not have told him. That was despite the fact, or perhaps partly because, she knew she was talking to a machine. Others were convinced they were talking to a person just via a computer terminal. As a result it was suggested at the time that it might actually be used as a psychotherapist to help people with mental illness!
Weizenbaum was clear though that ELIZA was not an intelligent program, and it certainly didn’t care about anyone, even if it appeared to be. It certainly would not have passed the Turing Test, set previously by Alan Turing that if a computer was truly intelligent people talking to it would be indistinguishable from a person in its answers. Switch to any knowledge-based topic and the ELIZA DOCTOR script would flounder!
ELIZA was also the first in a less positive trend, to make chatbots female because this is seen as something that makes men more comfortable. Weizenbaum chose a female character specifically because he thought it would be more believable as a supportive, emotional female. The Greek myth Pygmalion from which the play’s name derives is about a male sculptor falling in love with a female sculpture he had carved, that then comes to life. Again this fits a trend of automaton and robots in films and reality being modelled after women simply to provide for the whims of men. Weizenbaum agreed he had made a mistake, saying that his decision to name ELIZA after a woman was wrong because it reinforces a stereotype of women. The fact that so many chatbots have then copied this mistake is unfortunate.
Because of his experiences with ELIZA he went on to become a critic of Artificial Intelligence (AI). Well before any program really could have been called intelligent (the time to do it!), he started to think about the ethics of AI use, as well as of the use of computers more generally (intelligent or not). He was particularly concerned about them taking over human tasks around decision making. He particularly worried that human values would be lost if decision making was turned into computation, beliefs perhaps partly shaped by his experiences escaping Germany where the act of genocide was turned into a brutally efficient bureaucratic machine, with human values completely lost. Ultimately, he argued that computers would be bad for society. They were created out of war and would be used by the military as a a tool for war. In this, given, for example, the way many AI programs have been shown to have built in biases, never mind the weaponisation of social media, spreading disinformation and intolerance in recent times, he was perhaps prescient.
by Paul Curzon, Queen Mary University of London
Fun to do
If you can program why not have a go at writing an ELIZA-like program yourself….or perhaps a program that runs a job interview for a particular job based on the person specification for it.
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This page and talk are funded by EPSRC on research agreement EP/W033615/1.
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