Reference and Working Memory: What Discourse Can Tell us about Cognition

1. Reference and Working Memory:What Discourse Can Tell us about Cognition Andrej A. Kibrik (kibrik@chat.ru) (Institute of Linguistics, Moscow, and MPI for Evolutionary Anthropology, Leipzig)

2. INTRODUCTIONThe phenomenon: Referential choice in discourse • When people speak or write, they constantly mention various referents (persons, animals, objects, abstract notions, etc.) • Basic referential choice: • full noun phrase (full NP) • pronoun • zero form

3. An example(from the web page of the city of Dresden) • 1. Johann Friedrich Böttger • Ø Alchemist and inventor, Ø born 4.2.1682 in Schleiz, Ø died 13.3.1719 in Dresden. Böttger was imprisoned as an alchemist in Königstein Fortress in 1703. In 1707 his laboratory was transferred to the Jungfernbastei, a bastion of the Dresden City fortifications. It was here, a year later, that he discovered the formula for the first European porcelain and the world's first hard porcelain. Böttger also achieved certain results as a botanist in Dresden, Ø setting up a greenhouse with over 400 rare plants. In 1710 he was ordered to Meissen as administrator of the royal porcelain manufactory. zero Full NP pronoun

4. Summary of the talk • Part I: A linguistic study of referential choice in natural discourse • Part II: Consequences of that study for the broader field of working memory research

5. PART I: THE LINGUISTIC STUDYThe problem • How does the speaker make the referential choice between full noun phrases and reduced noun phrases, such as pronouns? • Note: This problem is really fundamental; at least every third word in natural discourse depends on referential choice.

6. Prior studies: huge literature, including: • Linguistics, e.g.: • Fox, Barbara. 1987. Discourse structure and anaphora in written and conversational English. Cambridge: CUP • Psycholingustics, e.g.: • Gernsbacher, Morton Ann. 1990. Language comprehension as structure building. Hillsdale, NJ: Erlbaum. • Cognitive psychology and neuroscience, e.g.: • Streb, Judith & Roesler, Frank & Henninghausen, Erwin. 1999. “Event-related responses to pronoun and proper name anaphors in parallel and nonparallel discourse structures”. Brain and Language 70: 273-286.

7. Different terminologies • Coreference • Anaphora • Reference tracking • Reference maintenance • Management of reference • Referential choice

8. Important terms coreferential Johni was sitting at the table. Hei was daydreaming about the weekend antecedent Referential device/expression

9. Goal • To construct a model of referential choice in discourse

10. Properties of the present model • speaker-oriented (rather than addressee-oriented or text-centered) • sample-based (rather than based on a heterogeneous set of examples) • general (rather than tolerant to exceptions) • predictive and finite (rather than post-hoc repairing to account for individual cases) • explanatory (rather than based on the black box ideology) • cognitively based (rather than relying on home-made quasi-cognitive concepts) • multi-factorial (rather than assuming one omnipotent factor) • testable and calculative (rather than declarative)

11. The cognitive assumptions • The primary cognitive determiner of referential choice is activation of the referent in question in the speaker’s working memory (WM). • Referent’s activation score (AS) varies within a certain range (e.g. between 0 and 1). • If the current activation score is above a certain threshold, then a semantically reduced (pronoun or zero) reference is possible, and if not, a full NP is used.

12. This model continues the lines of: • Cognitively minded linguistic research, such as: • Chafe, Wallace. 1994. Discourse, consciousness, and time. The flow and displacement of conscious experience in speaking and writing. Chicago: University of Chicago Press. • Tomlin, Russell & Pu, Ming-Ming. 1991. “The management of reference in Mandarin discourse”. Cognitive Linguistics 2: 65–93 • Kibrik, Andrej A. 1991. “Maintenance of reference in sentence and discourse”. In: Lehmann, Winfred P. & Hewitt, Helen‑Jo J. (eds.) Language typology. Amsterdam: Benjamins, 57-84.

13. And attempts to be compatible with: • Cognitive-psychological and neuropsychological work on working memory • Baddeley, Alan. 1990. Human Memory: Theory and Practice. Needham Heights, Mass: Allyn & Bacon. • Cowan, Nelson. 1995. Attention and Memory: An Integrated Framework. New York – Oxford: Oxford University Press. • Smith, E.E. & Jonides J. 1997. “Working memory: A view from neuroimaging”. Cognitive Psychology 33, 5–42.

14. The cognitive multifactorial model of reference in discourse production Discourse context Referent’s activation score (AS) Referential choice Filters Properties of the referent Activation factors

15. The original study • Referential choice in Russian narrative discourse (Kibrik 1996) • Main results • About seven to ten significant activation factors • Numerical model of factor interaction • Complete prediction of the data in corpus • Almost complete prediction in the test corpus

16. A study of referential choice in English narrative discourse • “The Maggie B.” by Irene Haas • Discourse type: • written narrative • simple, clear style • basic event types: physical events, interaction of people, human reflections… • Number of discourse units: 117 • Number of referents: 76 • Number of referent mentions: 225 • Number of “important” referents: 14 • Number of protagonist referents’ mentions: Margaret – 72, James – 28, the ship – 12 • Number of “relevant” referential devices: full NPs – 39, activation-based pronouns – 40

17. Stages of model construction • I will explain the heuristics of model construction in terms of five consecutive stages, “A” through “E”.

18. Stage A:Identify alterable vs. unalterable referential devices 1502 A storm was coming!1503 Margaret must make the boat ready at once.1601 She (~Margaret) took in the sail1602 and tied it tight. 1603 She (*Margaret) dropped the anchor1604 and stowed all the gear <...> • Alterable and unalterable devices correspond to different activation levels

19. Attribution of referent mentions to “potential referential form” categories

20. Stage B:Identify the significant activation factors, as opposed to insignificant

21. Stage C:Specify the list of the significant activation factors • with the indication of: • the distinction between primary and secondary factors • logical structure of each factor • values of each factor • corresponding numerical weights of each value

22. Primary activation factors (variables), their values, and numerical activation weights

23. An example of a rhetorical graph(in accordance with the Rhetorical Structure Theory of Mann and Thompson)

24. Example of RhD  LinD(RhD is low and LinD is high) 1201 After juice-and-cookie time, she gave James his counting lesson, 1202 and this is how she did it. 1203 One, two, three, four, five, once I caught a fish alive, 1204 six, seven, eight, nine, ten, but I let him go again. 1205 Why did you let him go? 1206 because he bit my finger so. 1207 Which finger did he bite? 1208 This little one upon the right. 1209 And she gave James' little finger a nibble … RhD=1 LinD=7

25. Reference and discourse structure • Referential choice is fundamentally conditioned by discourse structure • The strongest activation factor is the rhetorical (hierarchical) distance to the antecedent • Reduced NPs are more likely to occur in coherent contexts

26. Primary activation factors...(continuation)

27. Reference and the properties of antecedent/referent • Antecedent role is the second strongest activation factor: subjects make very good antecedents • More permanent referent properties (protagonisthood, animacy) play the role of correction/compensation factors

28. Activation weights • Present model: weights found through a trial-and error procedure, by hand • Ideal model: weights found through a computational procedure, automatically

29. Stage D:Identify the mechanism of factor interaction • Present model: addition of all relevant activation weights; the resulting AS varies within the limits from 0 to a bit over 1. • Ideal model: multiplication or more complex interaction of the factors’ activation weights

30. Stage E: Identify referential strategies, or mappings “AS  referential choice”

31. A probabilistic reinterpretation of referential strategies: 4 thresholds Pronoun only Pronoun OK Full NP OK Full NP only

32. An example of calculating a referent’s current AS

33. PART II:Consequences for working memory studies • Some classical issues in WM research: • (1) WM capacity: how much information can WM hold at one time? • (2) Control of WM: through what mechanism does information enter WM? • (3) Forgetting: through what mechanism does information quit WM?

34. Issue 1:Capacity • The procedure of calculating the referents’ ASs does not depend on whether a given referent is actually mentioned at the present point • For any referent, its AS can be identified at any time • Therefore, summary (grand) activation of all referents can be calculated for any moment of discourse

35. The dynamics of two protagonist referents’ activation and of grand activation in an excerpt of English narrative

36. Generalizations about WM capacity • Grand activation is an estimate of the specific-referent portion of WM • The maximal values of grand activation are between 3 and 4 (cf. an identical estimate in Cowan 2000) • Grand activation varies much less than activation of individual referents • In the course of coherent stretches of discourse (paragraphs) grand activation gradually builds up • At the points of incoherence (paragraph boundaries) WM is reset or updated.

37. Issue 2:Control of WM • WM is controlled by the attentional system of the brain (Baddeley 1990, Cowan 1995, Posner & Raichle 1994: 173). • Focal attention is linguistically rendered by the syntactic status of subject (Tomlin 1995) • Subjects are the best antecedents, both discourse- and sentence-wide

38. Cognitive and linguistic interplay between attention and WM • Attention feeds WM: What is attended at moment tn becomes activated in WM at moment tn+1 • Linguistic moments are discourse units • Focally attended referents (moment tn) are coded by subjects • Activated referents (moment tn+1) are coded by reduced NPs (pronouns)

39. Cognitive and linguistic interplay between attention and WM: Summary

40. Issue 3:Forgetting • “Trace decay” theory: Forgetting is a function of time • “Interference theory”: Forgetting is a result of displacement by new incoming information

41. Linguistic data are compatible with the trace decay theory • Activation decreases as distance to the antecedent becomes greater • The limit on the number of concurrently activated referents can be explained by WM capacity limitations • The balanced system of activation factors activates and deactivates referents in accordance with WM capacity limitations

42. Conclusions • Capacity of WM for referents is severely limited (3 to 4 times maximal activation of a single referent) • Referents enter WM through the mechanism of attentional control • Referents can be forgotten from WM through the mechanism of decay

43. Really final conclusions • Linguistic discourse analysis can indeed contribute to explorations of the human cognitive system • It is the time for a close cooperation between linguistics and psychology in the study of cognition