1. An Electrophysiological Investigation of the Effects of Coreference on Word Repetition and Synonymy Jane E. Anderson & Phillip J. Holcomb 2005 Presented by Dora Lu for Psych593SG

2. Coherent Speech …

3. How to relate new and old information? (1a) The truck rolled into a ditch as the driver was flagging down a passing car. Noun repetition (2a) The truck had a bad parking brake. Synonym (2b) The vehicle had a bad parking brake. Anaphors: pronouns (2c) It had a bad parking brake.

4. Goals of this study How the neural system underlying text comprehension use ‘ noun repetition ’ and ‘ synonym ’ to refer to a previously mentioned instance. - repetition and semantic priming effect (lexical/semantic memory effects or a discourse factor) - coreferential effect elicited by definite and indefinite article

5. Repetition Effect Robust in lexical decision, word identification and naming tasks -Behavioral: words are processed faster and more accurately when they are preceded by an earlier presentation of the same word From Scarborough et al. (1977)

6. Repetition Effect: ERP Repeated items: Attenuation of the N400 The augmentation of a subsequent late positive component (LPC)

7. LPC (Rugg 1987)

8. Semantic Priming Effect Behavioral: when a target word is preceded by a semantically related priming word, RTs are shorter dog …… cat ERP: - the N400 is attenuated if compared to an unrelated prime word preceding the same target word. dog …… cat vs. pan …… cat - Semantic priming does not results in an enhancement of the subsequent LPC

9. Priming Effect Why smaller N400? -Reflect the ease of integrating the semantic information activated by a primed word (Holcomb 1993)

10. Priming Effect -The late positive component (LPC) reflects a larger discrepancy between the baseline familiarity of low frequency words and their high experimental familiarity (Rugg, 1990)

11. Repetition Effect in longer texts Van Petten et al (1991): reading texts from Readers ’ Digest -Found ERP repetition effects during text processing. -Opposite results: Larger LPC for not repeated words

12. N400 and global processing St. George et al. (1989): N400 to content words was larger when the paragraph was not coherent (i.e. paragraph did not have a title)

13. N400 and global processing N400 for discourse anomalies (Van Berkum et al 1999) As agreed upon, Jane was to wake her sister and her brother at five o ’ clock. But the sister had already washed herself and the brother have even got dressed. a) discourse-coherent: Jane told the brother that he was exceptionally quick. b) discourse-anomalous: Jane told the brother that he was exceptionally slow. The N400 to the discourse anomaly had a similar time course, distribution and morphology compared to the N400 elicited by a local anomaly.

14. N400 and global processing Subsequent definite noun elicited a more negative-going waveform compared to when there was only one potential referent (Van Berkum et al 1999). One referent: David had told the boy and the girl to clean up their room before lunch time. But the boy had stayed in bed all morning, and the girl had been on the phone all the time. Two referents: David had told two girls to clean up their room before lunch time. But one of the girls had stayed in bed all morning, and the other had been on the phone all the time. David told the girl that there will be some vistors. These effect have been replicated in auditory modality as well (Van Berkum et al 2003)

15. Processing of definite/indefinite noun phrases: Behavioral: Irwin et al. (1982): -Repeated words were faster than not repeated words -Words preceded by the definite article were responded even faster  definite article provides a cue for old information and this facilitates its processing Murphy (1984): -RTs for sentences containing definite article are faster than sentences containing indefinite article.  Finding the antecedent for a definite reference is easier than establishing a new referent.

16. However, these behavior studies cannot tell us … On-line comprehension process. Lexical decision task may encourage people to adopt unnatural sentence processing strategies. Lexical decision task doesn ’ t allow people to examine the repetition and coreference effects in longer contexts.

17. Current Study Repetition priming condition: Kathy sat nervously in the cab on her way to the airport. a) The cab came very close to hitting a car. b) A cab came very close to hitting a car. Synonym (semantic) priming condition: Kathy sat nervously in the taxi on her way to the airport. a) The cab came very close to hitting a car. b) A cab came very close to hitting a car.

18. Predictions If N400 is also sensitive to coreference (a discourse factor), then …. For repetition priming condition: -stronger repetition effects for words preceded by the definite article.  Greater attenuation of the N400 For semantic priming condition: -similar as repetition effects but to a lesser degree Kathy sat nervously in the cab on her way to the airport. a) The cab came very close to hitting a car. b) A cab came very close to hitting a car.

19. Predictions If N400 is primarily sensitive to lexical/sentential processes, then …. Equivalent N400 attenuation for words following definite and indefinite articles. May have other ERP components that are sensitive to coreference (i.e. LAN).  repeated and synonym noun phrases following definite articles should produce a larger LAN.  the indefinite noun phrases will have a larger LAN, because they are harder to integrate  processing difficulties may be indexed by N400, LAN or other components Kathy sat nervously in the cab on her way to the airport. a) The cab came very close to hitting a car. b) A cab came very close to hitting a car.

20. Predictions Sentence final words … Osterhout & Holcomb (1992): sentence final words from sentences that are semantically difficult to interpret have larger N400.  sentences with indefinite article should have larger negativity. Kathy sat nervously in the cab on her way to the airport. a) The cab came very close to hitting a car. b) A cab came very close to hitting a car.

21. Summary of predictions: Component Target Word N400LANOthers discourselexicalWM load Integration Processing difficulties could be indexed by both N400 + LAN The cab smaller Same amount of attenuation Larger smaller A cab Larger smaller Larger Final word Larger for indefinite sentences Kathy sat nervously in the cab on her way to the airport. a) The cab came very close to hitting a car. b) A cab came very close to hitting a car.

22. Experiment 1 A control study to verify … -the differences they found are not due to the inherent (physical/lexical) differences between ‘ The ’ and ‘ A ’ -determine the ‘ carry-over ’ effect

23. Experiment 1: Stimuli Experimental (repetition) - Kathy sat nervously in the cab on her way to the airport. a) The cab came very close to hitting a car. b) A cab came very close to hitting a car. Experimental (synonym) -Kathy sat nervously in the taxi on her way to the airport. a) The cab came very close to hitting a car. b) A cab came very close to hitting a car. Filler: -Joanne had just won her bet at the horse races. She waited in line to get 75 dollars. Anomaly: -Joshua was riding on his bus to school one morning. A bus was stalled at the butter

24. Experiment 1: Stimuli Experimental (120) - Kathy sat nervously in the cab on her way to the airport. a) The cab came very close to hitting a car. (60) b) A cab came very close to hitting a car. (60) Experimental (synonym) -Kathy sat nervously in the taxi on her way to the airport. a) The cab came very close to hitting a car. b) A cab came very close to hitting a car. Filler: (30) -Joanne had just won her bet at the horse races. She waited in line to get 75 dollars. Anomaly: (30) -Joshua was riding on his bus to school one morning. A bus was stalled at the butter

25. Experiment 1 Participants: 24 Procedure: -central presentation, one word at a time -determine sentences are good or anomalous -A rest break after 30 trials. 4 true/false comprehension questions at each break.

26. Experiment 1: procedure + 500ms The 345ms 500ms cab 345ms Comprehension question …… 70ms Respond now car 70ms 1500ms Respond now 345ms Yes or No 2000ms Yes or No

27. Experiment 1: Data Data recording: 13 locations, referenced to left mastoid. Data analysis: -time locked to articles -time locked to the critical noun -time windows onset 150ms300600450750900105012001350ms (P2, N280)(N400, N400-700)(critical word N400, LAN) (400-700, 700-1100ms for final word)

28. Experiment 1: Results a) The cab came very close to hitting a car. b) A cab came very close to hitting a car.

29. Experiment 1: Results a) The cab came very close to hitting a car. b) A cab came very close to hitting a car.

30. Experiment 1: Results a) The cab came very close to hitting a car. b) A cab came very close to hitting a car.

31. Experiment 1: Results a) The cab came very close to hitting a car. b) A cab came very close to hitting a car.

32. Experiment 1: Results If time-locked to article: If time-locked to critical noun: Between 300-600ms, words following definite article were more negative 150-300ms300-600ms715- 1015ms Final word (400-700, 700-1100) Indefinite more negative Indefinite more negative, anterior distribution No differences no differences

33. Experiment 1: discussion Both articles elicited N280 and N400- 700, typical pattern for closed class words. Words following the indefinite article ‘ A ’ were more negative over the anterior cites.  not coreference, but due to the lexical function of the articles.

34. Why greater negativity for the indefinite article? The indefinite article reflects the anticipation of ‘ new ’ information. This might relate to the contingent negative variation (CNV). (Van Petten and Kutas 1991)

35. Contingent negative variation (CNV) Chronometric paradigm: paired-stimulus. CNV: a slow negative component that develops between a warning stimulus and a subsequent imperative stimulus. Usually observed when subjects performed a task requiring motor responses. Reflecting the anticipation or preparation for incoming information. Warning stimulus Imperative stimulus foreperiod respond

36. Why greater negativity for the indefinite article? There is a preference for the definite article at the beginning of sentences and for the indefinite article in the object position (Yekovich et al. 1979) The difference is due to the physical attributes of the articles. Word length is a predictor of negativity (Osterhout et al 2002). Word length and CNV: indefinite article was accessed in less time, given more time to anticipate the next word, which results in an enhanced CNV.

37. Experiment 1: discussion Time locked to article, no differences in the ERPS to critical nouns following the articles  no carry over Conditions do not differ in final word  article differences in the beginning of the sentence do not affect sentence wrap up effect

38. Experiment 2: Stimuli Experimental (repetition) (60) - Kathy sat nervously in the cab on her way to the airport. a) The cab came very close to hitting a car. (30) b) A cab came very close to hitting a car. (30) Experimental (synonym) (60) -Kathy sat nervously in the taxi on her way to the airport. a) The cab came very close to hitting a car. (30) b) A cab came very close to hitting a car. (30) Filler: (30) -Joanne had just won her bet at the horse races. She waited in line to get 75 dollars. Anomaly: (30) -Joshua was riding on his bus to school one morning. A bus was stalled at the butter

39. Experiment 2: procedure + 500ms 345ms 500ms 345ms 70ms 370ms 345ms 1500ms Yes or No (SOA:715ms) The cab …… car Next word (SOA:415ms) …… Last word Respond now

40. Experiment 2 results: article effects (150-300ms) Kathy sat nervously in the cab on her way to the airport. a) The cab came very close to hitting a car. b) A cab came very close to hitting a car.

41. Experiment 2 results: article effects (300-600ms) Kathy sat nervously in the cab on her way to the airport. a) The cab came very close to hitting a car. b) A cab came very close to hitting a car.

42. Experiment 2 results: article effects (715-1015ms) Kathy sat nervously in the cab on her way to the airport. a) The cab came very close to hitting a car. b) A cab came very close to hitting a car.

43. Experiment 2 results: article effects (715-1015ms) Kathy sat nervously in the cab on her way to the airport. a) The cab came very close to hitting a car. b) A cab came very close to hitting a car.

44. Experiment 2: priming effect Effects of repetition and semantic priming: repeated words are less negative. Kathy sat nervously in the cab on her way to the airport. (repetition) Kathy sat nervously in the taxi on her way to the airport. (synonym) A/The cab came very close to hitting a car.

45. Experiment 2: priming effect Kathy sat nervously in the cab on her way to the airport. (antecedent) Kathy sat nervously in the taxi on her way to the airport. (antecedent) a) The cab came very close to hitting a car. (repetition) b) A cab came very close to hitting a car. (synonym)

46. Experiment 2: Results The N400 amplitude of content words declines with increasing sentence position, reflecting the build-up of contextual constraints. (Van Petten & Kutas 1990) The declination has not been found with longer texts (Van Petten 1995) So, what does the smaller N400 for repeated and synonym words mean? Larger build-up of context?

47. Experiment 2: priming effect Joanne had just won her bet at the horse races. (filler) a) The cab came very close to hitting a car. (repetition) b) A cab came very close to hitting a car. (synonym)

48. Experiment 2: results The priming effect was not modulate by coreferential status.

49. Experiment 2: results Final word: negative-going component onset at about 300ms. Waveforms start diverging around 400ms and last throughout. In 400-700ms window, main effect of coreferential status. Indefinite sentences more negative. Larger effect at central and posterior sites.

50. Discussion: comparison of exp1 and exp2 Indefinite article ‘ A ’ elicited a greater N400-700 than the definite article ‘ The ’ with (exp2) or without (exp1) context.  processing differences even when the definite article ‘ the ’ does not explicitly refer to given information. The greater negativity of indefinite article could be reflecting the anticipation of the upcoming noun. But not sure if this is due to discourse factors, word length or other factors. No P2 found in exp2. This could be a carry-over effect in exp1, or this is an exogenous component related to word size. Subjects read a lead-in sentence in exp2. Found repetition/semantic priming effects (N400 attenuation) across sentence boundary.

51. Discussion Priming effects were not modulated by the coreferential status. Why? -the priming effects are so strong that they obscure the weaker coreference effect. Coreferential effect: different than N400 in: 1)distribution. Greater negativity over left anterior and temporal sites to coreferential words (definite). 2)Opposite polarity. Coreferential items have larger negativities.  Coreferential effects elicited LAN.

52. LAN Elicited by syntactic violations (Osterhout & Holcomb 1992)  But coreference is not a syntactic anomaly. Elicited by the increasing demands on working memory. (King & Kutas 1995) LAN to verbs in object relative sentences. Thematic role assignment is a harder process in object relative clauses. The head noun must be reactivated to be assigned and which increases working memory load. The reporter who the senator harshly attacked admitted the error. The reporter who harshly attacked the senator admitted the error. For the definite article, the referential assignment causes an increase in the working memory load.

53. Correferential effects: LAN in exp2 a) The cab came very close to hitting a car. b) A cab came very close to hitting a car.

54. Final word effects a) The cab came very close to hitting a car. b) A cab came very close to hitting a car.

55. Final word effect Non-coreferential sentences are more negative. Not shown on the critical noun, but could be a delayed effect, because they have similar distribution to the N400 (central- parietal). This effect could reflect difficulty in integrating the meaning of sentences that began with indefinite article. Coreferential trials are more coherent than the non- coreferential ones.

56. LPC No LPC found. Why? -words in this study were not low in frequency -rapid presentation rate in this study precluded the presence of late positivity.

57. Summary: Component Target Word N400LAN Repetition effect discourselexicalWM load Integration Larger N400 for repeated words, and this effect extended to a discourse level. The cab smaller Same amount of attenuation Larger smaller A cab Larger smaller Larger Final word Larger for indefinite sentences Kathy sat nervously in the cab on her way to the airport. a) The cab came very close to hitting a car. b) A cab came very close to hitting a car.

58. Thank you! Questions to Susan or me ? Comments?

59. Questions Compare the repetition and synonym with the first content word of the fillers. No fixed position and word classes? The ‘ antecedents ’ in the first sentence always preceded by the definite article. It somehow makes the indefinite NP in the beginning of the second sentence less preferable. Would it be better to manipulate the articles in the first sentence too?