How realistic is bidirectional optimization?

1. How realistic is bidirectional optimization? Reinhard Blutner http://www.blutner.de blutner@uva.nl Institute for Logic,Language and Computation

2. Introduction • Three notations of bidirectionality • Relevance for language acquisition

3. Three kinds of bidirectionality Routinization bidirectionality in actual competence / performance bidirectional learning bidirectionality in an evolutionarysetting (Zipf’s two economies) Fossilization

4. Bidirection in actual competence/?performance Competence: • OT phonology, OT syntax  Speaker’s view • OT semantics  Listener’s view • OT pragmatics  Integration of both views Performance: • Naïve picture (optimal generation/interpretation) • Analysis by synthesis? (interpr. involves generation) • Monitoring mechanisms? (generation involves interpr.) • Full bidirectionality?

5. Generation Interpretation Bidirectional learning and language aquisition F , M • Bidirectional learning of constructions ( symmetry) • Other mechanisms? (endogenous changes of architec-ture, maturation, …)

6. Outline • OT pragmatics (Motivating the unique role of bidirectional learning) • The use of bidirectional learning • Routinization • Fossilization • Example (acquisition of binding principles)

7. 2OT Pragmatics • Grice and his legacy • Global and local theories of pragmatics • Example of OT pragmatics

8. Neo-Gricean Theories (Horn, Atlas) OT-Pragmatics Relevance Theory Presumptive Meanings Grice and his followers

9. OT pragmatics • Neo-Griceans pragmatics (Horn, Atlas, Levinson, …) can be formulated in terms of bidirectional OT. • Neo-Griceans normally take a normative stance. • OT is taken as a cognitive theory (Smolensky, Legendre) which can be used to make prediction about language processing and language acquisition. • OT pragmatics can be seen as a framework that performs a naturalization of different variants of neo- and post-Gricean pragmatics

10. Neo-Gricean Theories (Atlas, Horn) • The Q-Principle (Hearer-based): Say as much as you can!(modulo R) (Grice’s first quantity maxim and the first two manner maxims) • The R-Principle (Speaker-based): Say not more than you must!(modulo Q) (Grice’s second quantity maxim, relation maxim and the second two manner maxims)

11. Bidirectionality in Gricean pragmatics • Mc Cawley 1981: Kill and cause to die • Levinson: Litotes (happy and not unhappy) • Krifka: Vague and precise interpretations of measure terms • Reflexives and pronouns • Aissen (2003): Differential object marking • Aloni (2001, 2005): Pragmatics for propositional attitudes • Zeevat (2002; 2004): Discourse particles and presupposition. • Beaver (2004), De Hoop (2004), Hendriks (2004): Interpretation of stress and focus. • Henriëtte de Swart (2004): Marking and Interpretation of negation

12. M m F f Weak bidirectionality F M F: prefer economic formsM: prefer stereotypical meanings

13. Heuristics I-heur. M-heur. Anti-I Anti-M I-heuristic: What is expressed simply is stereotypically exemplifiedM-heuristic: What’s said in an abnormal way isn’t normal

14. M M M M m m m m F F F F f f f f Two types of theories Global theorybidirection optimization Local theories (heuristics) unidirectional optimization *F/m *f/M Complementary constraints {X, Y}: If constraint X determines a certain interpretation pattern, then Y determines a corresponding generation pattern, and vice versa. Examples: 1. {M, F}, 2. {*F/m, *f/M}

15. Preliminary conclusions • Are there systematic relation between the two types of theories? • The idea of Routinization (conventionalization/ fossilization) of implicatures

16. The idea of routinization • ‘Invited Inferences’ (Geis & Zwicky 1971). Mechanism of conventionalization for implicatures • Short-circuited implicatures (Morgan 1978; Horn & Bayer 1984) • Lexicalization (Cole 1975) • Fossilization of implicatures (Levinson 2000) • Traugott (1989…2005) extended the idea to explain language change • Mattausch (2004): Cultural evolution of binding theory.

17. 3Bidirectional learning • Routinization and bidirectional learning • Fossilization and iterated (bidir.) learning

18. Listener Speaker Variants of bidirectional learning FMF ’ F = F ’ ? If yes, nothing happens If no, adjustment: All constraints that favour (F, M) over (F ’, M) are promotedAll constraints that favour (F ’, M) over (F, M) are demoted

19. M M M M m m m m F F F F *F/m *f/M f f f f Routinization and bidirectional learning bidir. learning Bidirectional learning provides an explication of routinization. In the routinized system unidirectional optimization mechanisms are efficient.

20. Cultural evolution: Zipf 1949 • Two basic and competing forces • Speaker’s economy: Force of unification R • Hearer’s economy: Force of diversification Q • The two opposing economies are evolutionary forces, i.e. they are balanced during language evolution. • Languages are evolving via cultural rather than biological transmission on a historical rather than genetic timescale

21. Iterated learning and fossillization Population in pairwise interaction

22. Explaining Universals

23. Preliminary conclusions • Routinization (individual fossilization) via learning on an ontogenetic time scales (seconds-years) • Cultural fossilization via iterated learning/cultural evolution on a historical time scale (years-centuries) • In the routinized/fossilized system unidirectional optimization mechanisms are efficient.

24. 4The acquisition of binding behavior for pronouns and reflexives • The pronoun interpretation problem • Delayed bidirection vs. delayed principle B

25. The Pronoun Interpretation Problem • Young children have problems in interpreting pronouns but not in interpreting reflexives. • In production this asymmetry disappears and both pronouns and reflexives are produced correctly. • This conflicts with the usual claim that comprehension of a given form precedes production of this form • Hendriks & Spenader (2004) claim that bidirectional OT taken as an online mechanism can explain these findings.

26. Children’s Comprehension of Reflexives* • Here is an elephant and an alligator. The elephant is hitting himself. • Question: Does the sentence match the picture? • Children from age 4 on: Yes * I thank Petra Hendriks for allowing me to use her slides

27. Children’s Interpretation of Pronouns • Here is an elephant and an alligator. The elephant is hitting him. • Question: Does the sentence match the picture? • Children until at least the age of 6 or 7: Yes E.g., Chien & Wexler, 1990; Grimshaw & Rosen, 1990; Jakubowicz, 1984; Koster, 1993; McDaniel, Smith Cairns, & Hsu, 1990; McDaniel & Maxfield, 1992; McKee, 1992.; Spenader, Smits & Hendriks, subm.

28. Children’s Production of Pronouns • Task: Describe what you see on the picture. • Children between 4;6 and 7: Cf. De Villiers, Cahillane, & Altreuter, 2006; Spenader, Smits, & Hendriks, subm. The elephant is hitting him.

29. Children’s Production of Reflexives • Task: Describe what you see on the picture. • Children between 4;6 and 7: The elephant is hitting himself *The elephant is hitting him

30. Two Alternative Explanations within OTP • Hendriks‘ & Spenader‘s Delayed Bidirection • Tue proposal is that children begin with unidirectional optimization, and only later acquire the ability to optimize bidirectionally. Principle B of BT is an epiphenomenon. • Bidirection Learning and the delay of principle B • Rather than stipulating a change from unidirect-ional to bidirectional processing the effects of bidirectionality are handled by a mechanism of learning/ automatization (reranking the constraint)

31. Alternative 1: Delayed bidirection - I • PRINCIPLE A >> REFERENTIAL ECONOMY • Hearer‘s perspective: one optimal interpretation for self but two optimal interpretations for pro. • Speaker‘s perspective: correct unique form for each interpretation. proself disjconj

32. Alternative 1: Delayed bidirection - II • Unidirectional Optimization • Bidirectional Optimization • What‘s essential for this solution is that the hearer has to take a potential speaker into account disjconj proself

33. Speaker Hearer Speaker Hearer self nothing happens conj conj nothing happens disj pro disj conj Alternative 2: Delayed principle B proself disjconj Constraint B promoted

34. Conceptual problems with both alternatives • The constraints are partly stipulated • No constraint grounding!

35. 5Two simulation experiments • Early principle A – delayed principle B • Mattausch & Gülzow • Blutner

36. Hendriks & Rij (2009) B B A A _ A _ A _ B _ B Mattausch & Gülzow (2008), Part I Hypothetical corpus of modern English All constraints equally ranked in the initial state. Predicts early principle B!

37. Mattausch’s trick • Principle A and principle B are complementary • Contrary to the facts, the old model predicts early principle B effects in interpretation and late principle A effects in generation • In order to get the effects of late principle B in interpretation reverse interpretation and generation:  Analysis by synthesis (motor theory of perception)

38. Mattausch & Gülzow (2008), Part II Revised bidirectional optimality a. A meaning m is recoverable from a form f iff there is no form-meaning pair ‹f,m’› such that ‹f,m’› > ‹f,m›. b. A form-meaning pair ‹f,m› is speaker optimal iff either (i) m is recoverable from f and there is no pair ‹f ’,m› such that m is recoverable from f’ and ‹f ’,m› > ‹f,m›, or (ii) no form x is such that m is recoverable from x and there is no pair ‹f ’,m› such that ‹f ’,m› > ‹f,m›. c.A form-meaning pair ‹f,m› is hearer optimal iff there is no pair ‹f ’,m› such that ‹f ’,m› > ‹f,m›.

39. _ A _ B __ Pro __ Di Present simulation: general conditions • Full set of bias constraints: • Principle A, Principle • Principle B , Principle • Full set of markedness constraints: • Pro (prefer pronouns; *Struct), • Di (prefer disjoint interpretation), • Bidirectional learning, unidirectional optimization • Use 98% pronouns and 2% reflexives with correct interpretations (2 % errors only). • Harmony Theory with constraint demotion

40. Present simulation: identical initial weights Strength of constraints _ B – B Dashed lines: error display _ A – A __ pro – pro Weightsbias constraints: 0.01markedness constraints: 0.01 __ di – di

41. Present simulation: different initial weights Strength of constraints _ A – A Dashed lines: error display _ B – B 1 2 3 __ di – di Weightsbias constraints: 0.01markedness constraints: 0.02 __ pro – pro

42. Three stages pro disjconj • Initial state: markedness ›› bias • {A, } ›› … • {A, B} ›› … proself disjconj __ Pro proself disjconj

43. 6Conclusions • Bidirectional learning can explain the acquisition of binding principles without stipulating a change of the architecture (unidirectional  bidirectional) • “Early principle A – delayed principle B” is a consequence of general assumptions about the initial state. • We don’t need bidirectionality for describing actual competence/performance • Errors in actual performance can be derived along the lines developed by T. Biro.

45. Appendix

46. A Production Problem for R-Expressions • Hendriks, Englert, Wubs & Hoeks (to appear): Age differences in adults’ use of referring expression • Children and very old adults produce pronouns where R-expressions are more appropriate

47. Sentence Elicitation Study A woman hold-ing an ice cream cone iswalking past a road sign. She gives the girl an ice cream cone. The woman comes across a girl. Target Picture Topic shift she The woman buys another ice cream come. Well, the woman passes again an ice cream van. The girl is eating from the ice cream cone.

48. Results • Elderly adults produce (non-recoverable) pronouns significantly more often than young adults when refer-ring to the old topic in the presence of a new topic. • With respect to the comprehension task, no significant differences were found between elderly and young adults.

49. Different time scales Online processing Offline processing Learning including routinization Cultural evolution Biological evolution performance milliseconds performance seconds languages years UB centuries UG