Language Use and Understanding BCS 261

1. Language Use and UnderstandingBCS 261 Audience Design Elizabeth Riina February 11, 2004

2. Taking Perspective in Conversation: The Role of Mutual Knowledge in ComprehensionBoaz, Keysar, et al. 2000 • What is perspective? • What is the role of perspective in language comprehension? • What strategies do we use in identifying potential referents? • How do we resolve ambiguities in online processing?

3. Howdowe resolve ambiguity? • Some theories suggest that addresses rely on mutual perspective as a mechanism in language comprehension. • MUTUAL PERSPECTIVE = COMMON GROUND

4. Shared vs. Unshared When knowledge is shared, several potential referents may be available to both the speaker and the addressee. “Turn it up!”

5. Shared vs. Unshared When information is unshared, a potential referent may be available to only one’s own perspective. “turn it up!”

6. In both cases is referring to THE INTENDEDREFERENT The intended referent is the object that is meant to be identified during referential communication, by the speaker to the addressee.

7. What types of comprehension strategies are used to resolve ambiguities in online comprehension? What processes help us to disambiguate linguistic expressions?

8. A co-presence heuristic asserts that ambiguity is resolved by restricting the set of potential referents to those that are present in common ground. • When information is shared, the is in common ground. Some shared information may also be co-present. • In this case, that mutual knowledge also maintains an active presence.

9. An egocentric heuristic is a different type of comprehension strategy. • Potential referents are objects in one’s own perspective, and are not necessarily shared information. “turn it up!” POTENTIAL REFERENT POTENTIAL REFERENT

10. Error Correction The is mistaken as the intended referent when is not a mutually perceived object. When the addressee’s perception of a potential referent interferes with the mutually known shared referent, an error arises. An error occurs when the addressee goes to “turn it up” on this potential referent:

11. The Power of Common Ground Egocentric comprehension strategies are occassionally used… Errors are rarely made... WHY? • The influence of common ground is more powerful. • One’s perception of mutual knowledge (and common ground) usually intervenes and interrupts an egocentric interpretation. • Therefore, common ground guides the perception and comprehension of an intended referent.

12. Predictions: Keysar et al. 2000 1. Addresses occasionally use an egocentric comprehension strategy, even when they are consciously aware that a potential referent may not be mutually shared with the speaker. 2. Mutual knowledge is used in error correction: egocentric interpretation ---> incorrect referent ---> identify shared information ---> detect intended referent ....sometimes error correction occurs before an incorrect interpretation is physically displayed

13. Experiment #1 Which objects do addresses consider to be referents when both shared and unshared knowledge exists? • Used eye tracking data to record comprehension and identification of potential referents. • “Directors” verbally advised “addresses” in an object manipulation task • Two different perspectives were presented. • Did addresses consider this unavailable information in their decisions about intended referents?

14. Experimental Design Addressee Director

15. The addressee can see both and as “fish”. The director knows only of as “fish”. The is the shared information (common ground). Does the addressee consider this lack of mutuality in choosing an object manipulation, or does he rely on egocentric knowledge? What do eye tracking movements indicate?

16. Procedure • Object manipulation task; analysis through eye tracking devices • The addressee was led to believe that the director was not aware that unshared information existed. • However, the addressee’s perspective included referents that were knowingly unavailable to the director. • At some point, the director advised the addressee to manipulate an ambiguous object (ie the fish) So... Does the addressee consider intended referents that are not mutually shared with the director?

17. Results • The addressees’ eyes fixated the occluded slot almost twice as often when it contained a potential referent (test condition) than when it contained a non-referent (control condition). Keysar et al., 2000 • Addressees’ initial eye movements to the occluded objects were faster than initial movements to the shared referent. • Final fixations on the intended referent were delayed in the test (potential referent) condition as compared with the control condition.

18. Results, cont... test condition control condition # of fixations 1.01 0.65 total fixation time 420ms 178ms …addresses fixated more often, and for a longer time, on potential, unshared referents...despite the knowledge that they were inaccessible to speakers

19. Experiment #2 • Objective: • To further emphasize the • occluded objects to the addressee • Procedure: • Adressees set up the experimental • array and directly assisted • in hiding objects from the director’s view.

20. Results • Addressees fixated on the occluded slot almost 3x more in the test condition than the control condition. • 20% of the addresses reached for (5%) or grabbed (15%) the occluded objects that they had hidden. • This finding suggests that addressees considered the occluded object to be a potential referent, as in experiment 1.

21. Discussion and Conclusion The emphasis on the occluded object strengthens the results of experiment 1 in suggesting that addressees sometimes relied on an egocentric comprehension strategy. • The role of mutual knowledge in error correction • Delay: error correction ---> identification of intended referent • Shared knowledge: Addresses fixated more often and longeron shared than occludedbeforethe critical instructions • --after the referring instruction, the search was among both shared and occluded

22. Discussion and Conclusion cont... 1. Addresses sometimes use an egocentric strategy even when they know referents are unshared. • do not restrict search to shared referents • disregard common ground in comprehension • a mutual knowledge constraint? • no role ---> only error correction • partial role ---> a) reduced error probability • b) error correction

23. Discussion Questions 1) Which do you guys think is more plausible as the case for egocentric strategy reasoning, that common knowledge does not constrain comprehension,or that common knowledge partially constrains comprehension? 2) How would this heuristic apply to the more conceptual aspect of referential conversation, during which the topic at hand may be abstract, or if it is a concrete concept, the object the concept refers to might not be in the immediate environment. Is there a way to test this heuristic in a situation where the entities in a conversation are not salient in a sensory way? -Anthony Shook

24. Discussion Questions 1) I know a lot of people have a tendency, when faced with a task and know they're being recorded,to fully focus on whether or not they are getting everything right so they don't look bad. Would this hinder the results of these experiments if this was taken into account? 2) The conclusion of this study states that we tend to rely on information from our own perspective. What other perspective do we have? If something is important and is shared information, isn't that part of our perspective as well as the other person's? -Jessica DeSisto

25. Discussion Questions 1) How would having a view of what the director could see in addition to the addressee's own perspective affect the results? 2) What about if it were reversed and directors were shown which objects were occluded from the addressee's view and asked to give instructions keeping that in mind? Having neither of the people be scripted might be a good way to determine if remembering what has been occluded is an issue (I know they tried to correct for this in the second Experiment, but I'm not convinced). -Nicole Dobrowolski

26. Discussion Questions 1. While reading the article, I was under the impression for the first experiment that the addressee did not realize that the director had an occluded object. However, the author then stated in another section of the article that the addressee knew about the occluded object. Which is the case? Did the addressee know or not know that the director had an object that they could not see? 2. Does the fact that, during the second experiment (despite the addressee's knowledge of the occluded objects) the addresse refers back to the occluded objects means that the egocentric point of view unconsciously overrides all other stretegies that one would use to understand what is being refered to? -Jesse Blake

27. Discussion Questions 1) Why do you think the decision lag between the first and the last fixation was longer in the test condition compared with the control condition in experiment two? (See page 36 results and discussion section) Was it the egocentric interpretation strategy that led them to consider the wrong referent? 2) On page 37 in the paragraph before the conclusion Keyser et al. stated "they use a strategy that is relatively effective though prone to errors, in order to accommodate a limited mental capacity" What might this limited mental capacity be referring to? -MR