1. Hannah Rohde, Andy Kehler, & Jeff Elman UC San Diego
Where to next? Pronoun interpretation as a side effect of discourse direction
Hannah Rohde, Andy Kehler, & Jeff Elman
UC San Diego
CUNY Conference on Human Sentence Processing, March

2. Transfer of possession (Stevenson et al. 1994)
handed a book to ______________.
John
John He
Bill He
Bill He
thanked John
recommended it
Source
(subject)
Transfer Verb
Goal
(to-phrase)
Ambiguous
Pronoun Prompt
50/50: Goal continuations / Source continuations
No subject preference or grammatical parallelism
Two explanations considered:
Thematic Role Preference
Event Structure Bias

3. Outline Background: Rohde et al. 2006
Test Thematic-Role and Event-Structure biases
Alternative account: Discourse Coherence
Experiments 1 & 2: test predictions of a coherence-
based model using story continuations
Preliminary results: discourse effects in relative clause attachment

4. Explaining salience of Goal (Rohde et al. 2006)
Thematic role preference or event structure bias?
handed a book to ______ .
JohnSOURCE
BillGOAL He
was handing a book to ___ .
Equivalent thematic roles but different event structure
Effect of aspect
F(1,48)=50.622
p<0.0001
Goal bias ~ side effect of Event Structure

5. Effects of coherence (Rohde et al. 2006)
Establishing coherence: infer a relationship between the meanings expressed by two sentences (P&Q below) (Hobbs 1979, Kehler 2002)
Causal relations (Explanation, Result, Violated Expectation)
Matt passed a sandwich to David. He didn’t want David to starve.
[Explanation: Q  P]
Matt He
Matt passed a sandwich to David. He said thanks.
[Result: P  Q]
David He

6. Coherence cont. Similarity relations (Parallel, Elaboration)
Matt passed a sandwich to David. He did so carefully.
[Elaboration: infer P from both S1 and S2]
Matt He
Contiguity relations (Occasion)
[Occasion: infer initial state of event described in S2 to be final state of event described in S1]
Matt passed a sandwich to David. He ate it up.
David He

7. Discourse coherence effects (Rohde et al.)
Goal bias following perfective context sentences limited to Occasion & Result (see Arnold 2001)
Interpretation as side effect of coherence distribution

8. Shift coherence  shift interpretation
Test predictions of a coherence-driven model
More Occasion/Result  more Goal resolutions
More Explanation/Elaboration/Violated-Exp  more Source

9. Experiment 1: objects-of-transfer
Proposal: elicit different continuations with different objects
Stimuli: normal and bizarre objects
John handed a book to Bill. He ___________ .
John handed a bloody meat cleaver to Bill. He __ .
Predictions:
If… Abnormal objects  more Explanations
and Explanations  Source bias
More Source continuations for (9) than (8)

10. Methodology Subjects: 69 monolingual English speakers
Task: write 50 continuations, just like Rohde et al.
Stimuli: 21 transfer-of-possession like Rohde et al.
(+ bizarre objects)
Evaluation: judges assess coherence/interpretation
Analysis:
Effect of within-subject factor of Object Type on
Coherence (Elab/Expl/Occ/Par/Res/Viol-Exp)
Pronoun interpretation (Source/Goal)
Mixed-effects logistic regression
Controls for random effects of Subject and Item

11. } Results Coherence varies by object Consistent prob(Source|coh) Exp 1
Rohde et al.
Coherence
Elaboration
0.87
Violated-expectation
0.75
Explanation
0.99
0.16
Result
0.20
Occasion
0.45
Parallel
p<0.0001
Source
0.81
0.82
0.99
0.05
0.17
0.71
Goal }

12. Results No effect of object type on pronoun interpretation
Subjects: F(1,68)= 0.052
p<0.820
Items: F(1,20)=0.111
p<0.743

13. Experiment 2: ‘What next?’ or ‘Why?’
John handed a book to Bill. He ___________ .
Stimuli & Design: identical to Rohde et al. 2006
Instructions: write continuations answering either “What happened next?” or “Why?”
Predictions:
“What next?”  more Occasions  Goal bias
“Why?”  more Explanations  Source bias

14. Methodology Subjects: 42 monolingual English speakers
Task: identical to Rohde et al (w/instructions)
Stimuli: identical to Rohde et al. 2006
Evaluation: judges assess coherence/interpretation
Analysis:
Effect of between-subject factor of Instruction Type on coherence distribution & pronoun interpretation

15. Results Coherence varies w/instruction (p<0.0001)
Consistent prob(Source|coh)
Exp 2
Rohde et al.
Coherence
Elaboration
0.87
Violated-expectation
0.75
Explanation
0.99
0.16
Result
0.20
Occasion
0.45
Parallel
0.81
1.00
0.11
0.28
0.46
Source
Goal

16. Results Effect of Instruction type on pronoun interpretation

17. Predicting pronoun interpretation
Predict % Source Resolutions in Exp 2 using:
Exp2 coherence breakdown
Exp1 conditional probabilities
Coherence
p(Source)
Explanation
0.82
Elaboration
0.99
V-E
0.81
Occasion
0.17
Result
0.05
Parallel
0.45

18. Capturing subject variation
“What next” “Why”
linear regression R2=0.604
F(1,40)=61.097, p<0.0001

19. Consistency of biases across conditions
R2 value/ANOVA
Conditional Probability Estimator
Exp1: perf, normal objects
R2=0.606, F(1,40)=61.612*
Exp1: imp, normal objects
R2=0.627, F(1,40)=67.371*
Exp1: perf, abnormal objects
R2=0.561, F(1,40)=51.165*
Exp1: imp, abnormal objects
R2=0.586, F(1,40)=51.165*
Exp1: average across verbal aspects & object types
R2=0.604, F(1,40)=61.097*
* Indicates p<0.0001

20. Summary Shift coherence  Shift pronoun interpretation
No model relying only on surface-level cues can account for observed variation, since stimuli were near-identical (Exp 1) or identical (Exp 2)
Need richer models incorporating discourse-level factors (see Wolf et al. 2004; Kertz et al. 2006)

21. What else can discourse do for you?
Relative clause attachment ambiguity
high
low
Beth babysits the children of the musician who ____
musical prodigies themselves.
are
the children
at the club downtown.
plays
the musician
Function of a relative clause
John despises the employee who is always late.
Implicit Causality (NP2 IC) verbs attribute cause to direct object
Proposal: try to shift RC attachment using verbs that require Explanations and that attribute cause to the referent occupying higher NP

22. Predictions & results
nonIC: Beth babysits the children of the musician who _____
plays
at the club downtown.
the musician
 low
IC: Beth despises the children of the musician who ______
and yell during rehearsals.
scream
the children
 high
F(1,51)=31.082
p<0.0001
p<0.0001
 Further evidence that discourse influences interpretation

23. References
Arnold, J. E. (2001) The effects of thematic roles on pronoun use and frequency of reference. Discourse Processes, 31(2):
Chambers, G. C. & Smyth, R. (1998) Structural parallelism and discourse coherence: A test of Centering Theory. Journal of Memory and Language, 39:
Crawley, R., Stevenson, R., & Kleinman, D. (1990) The use of heuristic strategies in the interpretation of pronouns. Journal of Psycholinguistic Research, 4: 245–264.
Kameyama, M. (1996) Indefeasible semantics and defeasible pragmatics. In M. Kanazawa, C. Pinon, and H. de Swart, editors, Quantifiers, Deduction, and Context. CSLI Stanford, pp
Hobbs, J. R. (1979) Coherence and coreference, Cognitive Science, 3:67-90.
Hobbs, J. R. (1990) Literature and Cognition. CSLI Lecture Notes 21. Stanford, CA.
Kehler, A. (2002) Coherence, reference, and the theory of grammar. CSLI Publications, Stanford, CA.
Kertz, L., Kehler, A., & Elman, J. (2006) Grammatical and Coherence-Based Factors in Pronoun Interpretation. 28th Annual Conference of the Cognitive Science Society, Vancouver, July 2006.
Moens, M. & Steedman, M. (1988) Temporal ontology and temporal reference. Computational Linguistics 14(2):15-28.
Smyth, R. H. (1994) Grammatical determinants of ambiguous pronoun resolution. Journal of Psycholinguistic Research, 23:
Stevenson, R., Crawley R., & Kleinman D. (1994) Thematic roles, focusing and the representation of events. Language and Cognitive Processes, 9:519–548.
Wolf, F., Gibson, E. & Desmet, T. (2004) Coherence and pronoun resolution. Language and Cognitive Processes, 19(6):

24. Variation by instruction and aspect
Coherence (instr x aspect
interaction p<0.0001)
Interpretation (instr x aspect
interaction p<0.0001)
John was giving a book to Bill. He ___________ .
John gave a book to Bill. He ___________ .
…“What happened next?”

25. Discourse coherence effects