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What infants know about syntax but couldn’t have learned: experimental evidence for syntactic structure at 18 months Jeffrey Lidz, Sandra Waxman, Jennifer.

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Presentation on theme: "What infants know about syntax but couldn’t have learned: experimental evidence for syntactic structure at 18 months Jeffrey Lidz, Sandra Waxman, Jennifer."— Presentation transcript:

1 What infants know about syntax but couldn’t have learned: experimental evidence for syntactic structure at 18 months Jeffrey Lidz, Sandra Waxman, Jennifer Freedman Ashley David Sara McTaggart Annie Porter Ellen Ramsey

2 Two major views: Nativist view: Grammar acquisition depends on innate structures in addition to input Major support: “poverty of the stimulus” General learning view: Linguistic input is sufficient in explaining the child’s acquisition of grammar Uses general purpose learning mechanisms Background Information

3 Support for the Nativist View Poverty of the stimulus: Looking at NP structure and Anaphors Possibility of two representations of NP (containing a det, adj, and noun): Flat Nested Anaphors: Anaphoric elements substitute only for constituents. Example: I’ll play with this red ball and you can play with that one. What is one referring to? [ ball ] [ ball ] Background Information [ red ball ]

4 Noun Phrase Representations Flat structure hypothesis NP det adj N o the red ball Nested structure hypothesis NP det N’ adj N’ N o the red ball Background Information Support for the Nativist View

5 Flat vs Nested structure in children… One is anaphoric to N’ and this is only possible in the nested structure One is anaphoric to N’ and this is only possible in the nested structureBUT Even if a child used the flat structure, finding evidence that they were wrong would be difficult because every situation where one= [N’ red ball] true also makes one= [N°ball] true Even if a child used the flat structure, finding evidence that they were wrong would be difficult because every situation where one= [N’ red ball] true also makes one= [N°ball] true Background Information

6 Consider the following situation which would be needed to provide evidence against the flat structure: Consider the following situation which would be needed to provide evidence against the flat structure: Sally has a red ball but Julie doesn’t have one. Imagine that Julie has a ball, but it’s a blue ball. Imagine that Julie has a ball, but it’s a blue ball. In this case, interpreting one as referring to N° is false since one would be referring to ball, but Julie has a ball, just not a red ball. In this case, interpreting one as referring to N° is false since one would be referring to ball, but Julie has a ball, just not a red ball. Background Information Flat vs Nested structure in children… …continued Sally Julie

7 A child coming across this type of situation would have to come to the conclusion that their flat structure hypothesis was false and would have to change to the nested NP structure in order to have correct grammar. These types of situations are rare. So, if a learner started with the flat structure, it is possible that they would never get the evidence to lead them to the correct structure. Because there is no evidence of English speakers having a flat structure grammar, the idea is not considered. We assume the nested structure. Background Information …continued

8 Support for a nested structure… Hamburger & Crain (1984) found that children do represent the NP with a nested structure AND that they know one is anaphoric to N’ Hamburger & Crain (1984) found that children do represent the NP with a nested structure AND that they know one is anaphoric to N’…BUT Still not enough to describe how learners’ structure begins- as flat structure that matures into nested structure OR as a nested structure from the start Still not enough to describe how learners’ structure begins- as flat structure that matures into nested structure OR as a nested structure from the start Background Information

9 Corpus analysis Examined linguistic input of (2) children using CHILDES (found 792 anaphoric uses of one) Examined linguistic input of (2) children using CHILDES (found 792 anaphoric uses of one) Experimenters were interested in looking at the possibility of one as anaphoric to N’ not being available to learners Experimenters were interested in looking at the possibility of one as anaphoric to N’ not being available to learners Examined structures of antecedent Examined structures of antecedent Main idea: If there are a lot of instances of one referring unambiguously to N’- it is possible that input is significant for child to learn syntactic properties of one (general learning view) Main idea: If there are a lot of instances of one referring unambiguously to N’- it is possible that input is significant for child to learn syntactic properties of one (general learning view) ResultsIn 95% of the cases, the antecedent did not provide unambiguous indication of one referring to N’ Results: In 95% of the cases, the antecedent did not provide unambiguous indication of one referring to N’ ConclusionLinguistic input is insufficient for learner to know that one is anaphoric to N’ (nested structure) which supports the nativist view Conclusion: Linguistic input is insufficient for learner to know that one is anaphoric to N’ (nested structure) which supports the nativist view Support for the Nativist View

10 Experimentation Research question: Do infants know that one is anaphoric to N’ and thus have a nested NP structure? Research question: Do infants know that one is anaphoric to N’ and thus have a nested NP structure? Prediction: They do [have a nested structure] and will therefore interpret one as anaphoric to N’. Prediction: They do [have a nested structure] and will therefore interpret one as anaphoric to N’.

11 Subjects 24 English-speaking children (12 male; 12 female) 24 English-speaking children (12 male; 12 female) Age: 16m; 23d – 18m;15d (ave: 18m;3d) Age: 16m; 23d – 18m;15d (ave: 18m;3d) o Selected because just beginning to produce more than one-word utterances Two taken out because of failure to complete experiment Two taken out because of failure to complete experiment Experimentatio n

12 Materials Auditory stimuli Sentences & questions recorded in infant-friendly voice to be used as audio track with video in testing Sentences & questions recorded in infant-friendly voice to be used as audio track with video in testing Used objects whose names are normally recognized by infants of ~13 months + (a bottle, a car, a shoe, a bear) Used objects whose names are normally recognized by infants of ~13 months + (a bottle, a car, a shoe, a bear) Visual stimuli Constructed using computer drawing program Constructed using computer drawing program Brightly coloured & large to attract attention Brightly coloured & large to attract attention Of equal salience Of equal salience (Two) objects displayed on split-screen (side-by-side) (Two) objects displayed on split-screen (side-by-side) Experimentatio n

13 Set-up 18 in. 12 in. 20 in. 18 in. 12 in. 61 in. LCD screen Presents audio-visual materials Camcorder Projects images Experimentatio n Camcorder Records infant looking times & locations 80 in. Child (sitting on booster seat)

14 Procedure Playroom- Playroom- o parents were explained experiment, signed consent form, and completed vocabulary checklist Testing room- Testing room- o Parents instructed not to interact with child- sat behind child and wore visor that blocked view of screen so not to influence child’s direction of gaze Experimentatio n

15 Procedure (continued) Familiarization Phase Image of single object presented 3x Image of single object presented 3x Appeared alternating fashion on L or R screen accompanied by a recorded voice Appeared alternating fashion on L or R screen accompanied by a recorded voice Object was presented with a NP that included a Object was presented with a NP that included a det + adj + noun (example: Look! A yellow bottle.) Testing Phase Two objects appeared simultaneously side-by-side (on either side of the screen’s midline) Two objects appeared simultaneously side-by-side (on either side of the screen’s midline) Both images were from the same category as the familiarization object BUT only one was the same colour Both images were from the same category as the familiarization object BUT only one was the same colour Experimentatio n

16 Control condition- In the test phase, the child heard a neutral phrase: In the test phase, the child heard a neutral phrase: Now look. What do you see now? Anaphoric condition- In the test phase, the child heard a phrase containing the anaphoric one: In the test phase, the child heard a phrase containing the anaphoric one: Now look. Do you see another one? Each condition consisted of 4 trials (familiarization and test phase) Each condition consisted of 4 trials (familiarization and test phase) Children were randomly assigned to either condition Children were randomly assigned to either condition Test phase lasted 8 seconds Test phase lasted 8 seconds Entire experiment lasted 3 minutes 46 seconds Entire experiment lasted 3 minutes 46 seconds Procedure (continued) Experimentatio n

17 Familiarization Phase Example of Control Condition Look! A brown bear!

18 Familiarization Phase Example of Control Condition Wow! A brown bear!

19 Familiarization Phase Example of Control Condition Look! A brown bear!

20 Test Phase Example of Control Condition Now look. What do you see now?

21 Familiarization Phase Example of Anaphoric Condition Look! A yellow bottle.

22 Familiarization Phase Example of Anaphoric Condition Wow! A yellow bottle.

23 Familiarization Phase Example of Anaphoric Condition Look! A yellow bottle.

24 Test Phase Example of Anaphoric Condition Now look. Do you see another one?

25 Coding & Predictions Coding Durations of looking time to the L or R test image were coded afterwards by a single coder who watched the video of the session Durations of looking time to the L or R test image were coded afterwards by a single coder who watched the video of the session Another coder coded 25% of the data Another coder coded 25% of the data Inter-coder reliability- 96% Inter-coder reliability- 96%Predictions Control condition- linguistic stimulus does not favour one image over the other so expect child to look longer at novel image Control condition- linguistic stimulus does not favour one image over the other so expect child to look longer at novel image Anaphoric condition- where child looks should indicate their type of structure Anaphoric condition- where child looks should indicate their type of structure oIf represent with flat structure- either image could be referents of the noun  Linguistic stimulus is uninformative  Should see same as control (look to novel image) oIf represent with nested structure- should have preference for image that matches one as anaphoric to N’ (look to familiar object) Experimentatio n

26 Results Control condition Preference for novel image Preference for novel image Anaphoric condition More attention to familiar image than novel image More attention to familiar image than novel image Subjects in the anaphoric condition were more likely to look at the familiar image than were the subjects in the control condition Subjects in the anaphoric condition were more likely to look at the familiar image than were the subjects in the control conditionConclusion By 18 months of age infants interpret one as anaphoric to N’ and therefore represent NPs with a nested structure By 18 months of age infants interpret one as anaphoric to N’ and therefore represent NPs with a nested structure Experimentatio n What does this imply???

27 Figure 1. Mean looking time (in seconds) to the two test images in each condition Experimentatio n

28 Other possible interpretation of results… It could be the case that infants treat one as anaphoric to N° BUT BUT when they are asked to pick out another image that denotes, for them, N°- they have a preference for the familiar image (familiarity bias) SO… Conducted a control experiment to make sure this was not the case. Experimentatio n

29 Control Experiment Same as Experiment with the following exception… Same as Experiment with the following exception… Test phase, two conditions: Noun condition- children asked question that contained only the noun presented during familiarization (N°) Noun condition- children asked question that contained only the noun presented during familiarization (N°) Example: “Do you see another bottle?” Adjective-Noun condition- children asked question that had adj-noun combination heard in familiarization (N’) Adjective-Noun condition- children asked question that had adj-noun combination heard in familiarization (N’) Example: “Do you see another yellow bottle?”

30 Predictions and Results Noun Condition (where both are nouns): If children had a familiarity bias- would expect to see children looking longer at the familiar image If children had a familiarity bias- would expect to see children looking longer at the familiar image If children do not have a familiarity bias- would expect child to look at either image in the noun condition If children do not have a familiarity bias- would expect child to look at either image in the noun condition Adj-Noun condition Would expect child to look longer at the familiar object since only that image corresponds with the N’ Would expect child to look longer at the familiar object since only that image corresponds with the N’ Control Experiment What found

31 Figure 2. Mean looking time (in seconds) to the two test images in the control experiments Control Experiment

32 Interpretation of results… Because no familiarity bias was found- conclude that children choose familiar object (in anaphoric condition) because it matches their nested NP structure Control Experiment

33 Discussion Learners just beginning to combine words already have a rich syntactic representation Learners just beginning to combine words already have a rich syntactic representation Support for poverty of the stimulus Support for poverty of the stimulus Learners never consider that an element could be anaphoric to N° but behave like adults who consider one as anaphoric to N’ Learners never consider that an element could be anaphoric to N° but behave like adults who consider one as anaphoric to N’ Support for nativism- but experimenters still acknowledge role of input Support for nativism- but experimenters still acknowledge role of input END


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