This article, by Paul Curzon (QMUL) was originally published on the CS4FN website.
Sitting down and having a nice chat with a computer probably isn’t something you do every day. You may never have done it. We mainly still think of it as being a dream for the future. But there is lots of work being done to make it happen in the present, and the idea has roots that stretch far back into the past. It’s a dream that goes back to Alan Turing, and then even a little further.
The imitation game
Back around 1950, Turing was thinking about whether computers could be intelligent. He had a problem though. Once you begin thinking about intelligence, you find it is a tricky thing to pin down. Intelligence is hard to define even in humans, never mind animals or computers. Turing started to wonder if he could ask his question about machine intelligence in a different way. He turned to a Victorian parlour game called the imitation game for inspiration.
The imitation game was played with large groups at parties, but focused on two people, a man and a woman. They would go into a different room to be asked questions by a referee. The woman had to answer truthfully. The man answered in any way he believed would convince everyone else he was really the woman. Their answers were then read out to the rest of the guests. The man won the game if he could convince everyone back in the party that he was really the woman.
Pretending to be human
Turing reckoned that he could use a similar test for intelligence in a machine. In Turing’s version of the imitation game, instead of a man trying to convince everyone he’s really a woman, a computer pretends to be a human. Everyone accepts the idea that it takes a certain basic intelligence to carry on a conversation. If a computer could carry on a conversation so well that talking to it was just like talking to a human, the computer must be intelligent.
When Turing published his imitation game idea, it helped launch the field of artificial intelligence (AI). Today, the field pulls together biologists, computer scientists and psychologists in a quest to understand and replicate intelligence. AI techniques have delivered some stunning results. People have designed computers that can beat the best human at chess, diagnose diseases, and invest in stocks more successfully than humans.
A chat with a chatterbot
But what about the dream of having a chat with a computer? That’s still alive. Turing’s idea, demonstrating computer intelligence by successfully faking human conversation, became known as the Turing test. Turing thought machines would pass his test before the 20th century was over, but the goal has proved more elusive than that. People have been making better conversational chat programs, called chatterbots, since the 1960s, but no one has yet made a program that can fool everyone into thinking it’s a real human.
What’s up, Doc
On the other hand, some chatterbots have done pretty well. One of the first and still one of the most famous chatterbots was created in 1968. It was called ELIZA. Its trick was imitating the sort of conversation you might have with a therapist. ELIZA didn’t volunteer much knowledge itself, but tried to get the user to open up about what they were thinking. So the person might type “I don’t feel well”, and ELIZA would respond with “you say you don’t feel well?” In a normal social situation, that would be a frustrating response. But it’s a therapist’s job to get a patient to talk about themselves, so ELIZA could get away with it. For an early example of a chatterbot, ELIZA did pretty well, but after a few minutes of chatting users realised that ELIZA didn’t really understand what they were saying.
Where have I heard this before?
One of the big problems in making a good chatterbot is coming up with sentences that sound realistic. That’s why ELIZA tried to keep its sentences simple and non-committal. A much more recent chatterbot called Cleverbot uses another brilliantly simple solution: it doesn’t try to make up sentences at all. It just stores all the phrases that it’s ever heard, and chooses from them when it needs to say something. When a human types a phrase to say to Cleverbot, its program looks for a time in the past when it said something similar, then reuses whatever response the human gave at the time. Given that Cleverbot has had 65 million chats on the Internet since 1997, it’s got a lot to choose from. And because its sentences were all originally entered by humans, Cleverbot can speak in slang or text speak. That can lead to strange conversations, though. A member of our team at cs4fn had an online chat with Cleverbot, and found it pretty weird to have a computer tell him “I want 2 b called Silly Sally”.
Computerised con artists
Most chatterbots are designed just for fun. But some chatterbots are made for a more sinister intent. A few years ago, a program called CyberLover was stalking dating chat forums on the Internet. It would strike up flirty conversations with people, then try and get them to reveal personal details, which could then be used to steal people’s identities or credit card accounts. CyberLover even had different programmed personalities, from a more romantic flirter to a more aggressive one. Most people probably wouldn’t be fooled by a robot come-on, but that’s OK. CyberLover didn’t mind rejection: it could start up ten relationships every half an hour.
Chatterbots may be ready to hit the big time soon. Apple’s iPhone 4S includes Siri, a computerised assistant that can find answers to human questions – sometimes with a bit of attitude. Most of Siri’s humourous answers appear to be pre-programmed, but some of them come from Siri’s access to powerful search engines. Apple don’t want to give away their secrets, so they’re not saying much. But if computerised conversation continues advancing, we may not be too far off from a computer that can pass the Turing test. And while we’re waiting at least we’ve got better games to play than the Victorians had.