Language and Computers Dialog Systems Introduction Why dialogue? Human dialogue Basic facts Dialogue moves Language and Computers Speech acts Rules Early dialogue Dialog Systems systems ELIZA Other chatterbots Modern dialogue Based on Dickinson, Brew, & Meurers (2013) systems 1 / 38
What are dialogue systems good for? Language and Computers Dialog Systems Introduction Why dialogue? Anytime we have a straightforward task, dialogue systems Human dialogue seem like a good idea: Basic facts Dialogue moves ◮ We can book airline tickets over the phone without Speech acts Rules dealing with error-prone humans. Early dialogue systems ◮ We can interact with our computer while keeping our ELIZA Other chatterbots hands free. Modern dialogue systems ◮ We can talk to a system that won’t have the same prejudices a human might ◮ ... depending on the programmer) Before we look at dialogue systems, though, we need to understand something about human dialogue 2 / 38
Conversations Language and Computers The speaker’s perspective Dialog Systems Introduction Why dialogue? Human dialogue Basic facts Dialogue moves Conversations work because speakers & listeners Speech acts Rules understand a lot about dialogue Early dialogue systems 1. Why to speak : both assume a common goal ELIZA Other chatterbots 2. What to say : both can understand direct & indirect Modern dialogue systems statements, requests, questions, etc. 3. How to say it : both properly handle intonational changes, politeness conventions, etc. 3 / 38
Conversations Language and Computers The listener’s perspective Dialog Systems Introduction From the the listener’s perspective, they must make sense of Why dialogue? what is being said by the speaker, by: Human dialogue Basic facts 1. Accurately noticing what the speaker said . Dialogue moves Speech acts ◮ This involves hearing what was said, then breaking up Rules the speech signal into words and phrases Early dialogue systems 2. Working out the literal meaning of what was said . ELIZA Other chatterbots 3. Working out the reason that the speaker did what Modern dialogue systems they did . In order to do this, the listener has to reason about the speaker’s intent, on the basis of the observed evidence ◮ A first step toward building a computer that can do the same is to precisely describe how this process works in human-human dialog 4 / 38
Conversations Language and Computers Both perspectives Dialog Systems Introduction Why dialogue? Communicating is a collaborative event Human dialogue The speaker and the listener must manage the following Basic facts Dialogue moves processes, in real-time: Speech acts Rules 1. Speaking and listening in an orderly way, without talking Early dialogue systems over each other more than is acceptable. ELIZA Other chatterbots 2. Checking that the other person is understanding. Modern dialogue systems 3. Fixing confusions and misunderstandings before they cause the conversation to break down. Human beings are skilled in this activity long before they enter pre-school ◮ Trying to involve a computer in dialog makes the difficulties more evident 5 / 38
Why dialogues happen? Language and Computers Dialog Systems Introduction One of the main reasons for using language is in order to Why dialogue? collaborate with others on getting things done. Human dialogue ◮ If people have everything they need, or can get it Basic facts Dialogue moves without asking for help, there’s no real reason to speak Speech acts Rules ◮ More often, people and computer systems need to work Early dialogue systems with others in order to achieve their goals ELIZA Other chatterbots Dialog is full of rules and conventions that have evolved over Modern dialogue systems the years in order to make communication run smoothly ◮ A question is usually followed by an answer ◮ A request is often made indirectly because outright demands feel rude ◮ A refusal is often heavily disguised so as to soften the impact of the unexpected and unwelcome response 6 / 38
Automating dialogue Language and Computers Dialog Systems Introduction A sample dialog from the Let’s Go system Why dialogue? (http://www.speech.cs.cmu.edu/letsgo/example.html) Human dialogue Basic facts s : Thank you for calling the CMU Let’s Go! Bus Dialogue moves Speech acts Information System. This conversation will be recorded Rules for research purposes. If you do not want to be Early dialogue systems recorded, please hang up now. What can I do for you? ELIZA u : I would like to go to the airport tomorrow morning. Other chatterbots s : To the airport. When do you want to arrive? Modern dialogue systems u : I’d like to arrive at 10:30. s : Arriving at around 10:30 AM. Where do you want to leave from? u : I’d like to leave from Carnegie Mellon. s : From Carnegie Mellon. There is a 28X leaving Forbes Avenue at Morewood at 9:20 AM. It will arrive at Greater Pittsburgh Airport at Departure Stops at 10:15 AM. 7 / 38
Automating dialogue (2) Language and Computers Dialog Systems Introduction Why dialogue? Human dialogue u : When’s the next bus? Basic facts s : There is a 28X leaving Forbes Avenue at Morewood at Dialogue moves Speech acts 9:40 AM. It will arrive at Greater Pittsburgh Airport at Rules Departure Stops at 10:35 AM. Early dialogue systems u : I’d like to go from the airport back to CMU on Friday. ELIZA s : From the airport to CMU. When would you like to leave? Other chatterbots u : At 6:15 PM. Modern dialogue systems s : Leaving at around 6:15 PM. There’s a 28X leaving Greater Pittsburgh Airport at Departure Stops at 6:26 PM. It will arrive at Forbes Avenue at Morewood at 7:20 PM. u : Thank you very much. 8 / 38
Human dialogue Language and Computers Dialog Systems Introduction Why dialogue? Human dialogue Basic facts How does dialogue, or discourse (= conversation), work? Dialogue moves Speech acts Rules We will look at a few aspects of human-human interactions: Early dialogue systems ◮ Basic facts about dialogues ELIZA Other chatterbots ◮ Organization of conversation: Dialogue moves Modern dialogue systems ◮ What utterances do: Speech acts ◮ Rules of conversation: Gricean maxims 9 / 38
Basic facts about dialogues Language and Computers Utterances Dialog Systems Introduction People do not necessarily speak in sentences Why dialogue? ◮ Utterances : basic unit of conversation Human dialogue Basic facts ◮ may span over several turns Dialogue moves Speech acts ◮ may have several utterances within one turn Rules Early dialogue AGENT: Yeah yeah the um let me see here systems ELIZA we’ve got you on American flight Other chatterbots nine thirty eight Modern dialogue systems CUSTOMER: Yep. AGENT: leaving on the twentieth of June out of Orange County John Wayne Airport at seven thirty p.m. CUSTOMER: Seven thirty. AGENT: and into uh San Francisco at eight fifty seven. 10 / 38
Basic facts about dialogues Language and Computers Taking turns Dialog Systems Introduction Why dialogue? How humans communicate is relatively systematic Human dialogue Basic facts ◮ Turn-taking : must know when it’s the right time to Dialogue moves Speech acts contribute your turn Rules Early dialogue ◮ Comes naturally to humans: overlaps and long pauses systems are actually somewhat rare ELIZA Other chatterbots ◮ Adjacency pairs : two-part conversational structures Modern dialogue systems where turn-taking is usually quite clear ◮ question/answer: question is looking for an answer from dialogue partner ◮ greeting/greeting ◮ request/grant ◮ etc. 11 / 38
Basic facts about dialogues Language and Computers Common ground Dialog Systems Introduction Why dialogue? Human dialogue Basic facts Dialogue moves Common ground : the set of things which both speakers Speech acts Rules believe to be true of the conversation. Early dialogue systems ◮ Part of classroom common ground is that we are at ELIZA Other chatterbots Indiana in a linguistics class. Not part of the common Modern dialogue ground is what I had for lunch. systems ◮ People assess what others know before making a new contribution 12 / 38
Grounding Language and Computers Dialog Systems Introduction Why dialogue? In order to establish common ground, speakers do various Human dialogue things: Basic facts Dialogue moves Speech acts ◮ Backchannels = short utterance which indicates the Rules utterance was heard and that the speaker should Early dialogue systems continue. ELIZA Other chatterbots A: That’s a nice shirt. Modern dialogue systems B: Mm-hmm. ◮ Acknowledgment of utterance: continued attention, completing speaker’s utterance, and so on ◮ Asking clarifying questions 13 / 38
Dialogue moves Language and Computers Dialog Systems Introduction Why dialogue? Human dialogue Basic facts Dialogue moves Can view dialogue as a series of moves, as in a game Speech acts Rules 1. As an exchange has to start somewhere, we can group Early dialogue together a set of initiating moves systems ELIZA ◮ Making an assertion (“you have a friendly face”) Other chatterbots ◮ Issuing a command or making a request (“let’s go and Modern dialogue systems have a bite to eat”) ◮ Asking a question (“are you doing anything tonight?”) 14 / 38
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