Grounding in Communication

1. Grounding in Communication Herbert H. Clark and Susan E. Brennan

2. Foreword:On analyzing conversation • Real spoken conversation is very messy • incomplete sentences • overlapping turns • pauses • noisy voice data / unintelligible utterances • Clark uses some standard notation for analyzing conversation • write out what was said, not good English • pauses in conversation: . , - [2 seconds]

3. Grounding in Conversation • In order to have an effective conversation, the participants need to understand each other • To do this they need to ground their communication • Listener has to notice that something was said • Listener has to hear what was said • Listener has to understand what was said • Listener has to understand what was meant

4. Grounding in Conversation • So what is grounding? • Making sure that the listener understand what the speaker said • Making sure the speaker knows the listener understood • Making sure the listener knows the speaker knows the listener understood, etc.

5. So then what is common ground? • Information that participants know that they all know: • Common cultural and social history • Public history of the interaction • Current public state of the interaction • Common ground accumulates as the interaction continues

6. Evidence in Grounding • Speakers attempt to make sure they were understood by listeners • To do this, they look for evidence of understanding • Speakers can look for both positive and negative evidence

7. Negative feedback • Usually involves a new communicative action on the part of the listener • repetition • "- have a car?" • fill-in-the-blank • "have a what?" • asking questions or for clarification • many other methods

8. Positive feedback • continuers: *yeah*, mmhm, etc. • relevant next turns: i.e., something that makes sense in context and continues the conversation Miss Dimple: "Where can I get a hold of you?" Chico: "I don't know lady. You see, I'm very ticklish." • continued attention • Similar to continuants • But this can sometimes be hard to detect • HELLO! ANYONE AWAKE OUT THERE?

9. But... Why don't people justsay what they mean? • Principle of Least Collaborative Effort • Basically, people seem to minimize the amount of effort they have to put out to achieve understanding A: That tree has, uh, uh B: Tent worms. A: Yeah. B: Yeah. • But why? • Time pressure • Errors • Ignorance

10. Grounding Changes With Purpose • Participants alter their grounding methods according to situation and content • Alternative descriptions • Adding more detail to ensure grounding • Indicative gestures • Pointing, other gestures • Referential installments • Breaking a description into understandable chunks • Trial references • Speaker puts out a tentative reference; listener ratifies or rejects it

11. Grounding verbatim content • For complex content, participants have many strategies to ensure error-free communication • Verbatim displays A: "Waltham, MA, 02454" B: "0-2-4-5-4" A: "That's right." • Installments 123…45…6789 • Spelling Feinman, that's F-e-i-n-m-a-n

12. Grounding in different media • So how is this applicable to HCI? • Users of groupware systems will need to stay grounded • Constructing systems to support this grounding requires understanding how users operate • Different media that you provide will affect how users stay grounded • Clark identifies features of communication and relates how they affect grounding

13. Clark's features of communication • Copresence • Visibility • Audibility • Cotemporality • Simultaneity • Sequentiality • Reviewability • Revisability

14. Clark's features of communication • Copresence • Users are near each other, and can point at objects in common ground • Visibility • Users can see each other; allows gestures, facial expressions • Audibility • Users can hear each other, and use natural language • Cotemporality • Users can expect to receive a timely reply; interruptions or delays are significant

15. Clark's features of communication • Simultaneity • Users can send and receive at the same time; allows interruption, backchannel feedback • Sequentiality • User contributions are strictly ordered, and cannot get out of order • Reviewability • Users can look at the past history of the conversation • Revisability • Users have the option of editing their contributions before they commit to them

16. Some examples • Face-to-face • Copresence, visibility, audibility, Cotemporality, simultaneity, sequentiality • Telephone / Voice over IP • Audibility, cotemporality, simultaneity, sequentiality • Family radio / DirectConnect / walkie-talkies • Audibility, cotemporality, sequentiality • Email/SMS/Text messaging • Reviewability, revisability • Chat/IM/IRC/ICQ • Cotemporality, reviewability, revisability

17. Costs of Grounding • Different features affect cost for speaker and listener to ground communication • Cost of formulation (deciding what to say) • Cost of production (saying it) • Cost of reception (hearing it) • Cost of understanding (understanding it) • Cost of start-up (starting a conversation) • Cost of delay (what impact a delay has) • Cost of asynchrony (what impact misordering has) • Cost of speaker change or multiple speakers • Cost of display / pointing / graphical input • Cost of errors (in production or in understanding) • Cost of repairs

18. A made up example: face-to-face Student: I'm having trouble with my code. TA: Let me see… [looks at window full of code] Student: It doesn't compile, I think it TA: Did you include stdio dot h? [looks at student] Student: include what? TA: stdio.h . If you use printf or anything you need to include Student: um, [fidgets] TA: no, I don't see it there. You'll need to write Student: yeah [nods, moves to keyboard] TA: pound . err . sharp - shift-three - include angle bracket stdio.h angle bracket Student: ok [starts typing]

19. Now, in a chat room instead Student: I'm having trouble with my code. TA: Let me see…paste it in here Student: ok [pastes the code] TA: what's the problem? [copies and compiles the code] Student: it won't compile TA: looks like you need to include stdio.h TA: like this: #include <stdio.h> Student: ok TA: because you're using printf TA: does that make sense? Student: yeah, I think so. We talked about that in class.

20. Easier to point Easier to discuss Easier to gauge understanding … Easier to produce complicated content Easier to review history of conversation … Comparison:face-to-face v. chat

21. Conclusions • Grounding is essential to communication • Communication is a collaborative activity • Content affects grounding • Medium affects grounding