Ashley David Sara McTaggart Annie Porter Ellen Ramsey 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

Background Information 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 Poverty of the stimulus– input underdetermines the linguistic representations of the adult grammar Background Information

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 ] [ red ball ] Background Information

Noun Phrase Representations Support for the Nativist View Noun Phrase Representations Flat structure hypothesis NP det adj No the red ball Nested structure hypothesis NP det N’ adj N’ No the red ball The nested structure accounts for the anaphoric use of one since it is under this structure that red ball is represented as a constituent. Background Information

Flat vs Nested structure in children… One is anaphoric to N’ and this is only possible in the nested structure BUT 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

Flat vs Nested structure in children… Background Information …continued 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. 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. Sally Julie Background Information

Flat vs Nested structure in children… …continued 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

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’ …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 Background Information

Corpus analysis Support for the Nativist View 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 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) Results: In 95% of the cases, the antecedent did not provide unambiguous indication of one referring to N’ Conclusion: Linguistic input is insufficient for learner to know that one is anaphoric to N’ (nested structure) which supports the nativist view Antecedent is important because it has the potential of indicating whether one refers unambiguously to N’

Experimentation 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’.

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

Materials Experimentation Auditory stimuli Visual stimuli 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) Visual stimuli Constructed using computer drawing program Brightly coloured & large to attract attention Of equal salience (Two) objects displayed on split-screen (side-by-side)

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

Procedure Experimentation Playroom- Testing room- parents were explained experiment, signed consent form, and completed vocabulary checklist Testing room- 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

Procedure (continued) Experimentation Procedure (continued) Familiarization Phase Image of single object presented 3x Appeared alternating fashion on L or R screen accompanied by a recorded voice 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) Both images were from the same category as the familiarization object BUT only one was the same colour 4 trials that each included these two phases

Procedure (continued) Experimentation Procedure (continued) Control condition- 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: Now look. Do you see another one? Each condition consisted of 4 trials (familiarization and test phase) Children were randomly assigned to either condition Test phase lasted 8 seconds Entire experiment lasted 3 minutes 46 seconds

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

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

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

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

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

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

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

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

Coding & Predictions Experimentation Coding Predictions 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 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 Anaphoric condition- where child looks should indicate their type of structure If 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) If represent with nested structure- should have preference for image that matches one as anaphoric to N’ (look to familiar object) Preferential looking task- infants look longer at image that match linguistic stimulus if one is available

Results Experimentation What does this imply??? Conclusion Control condition Preference for novel image Anaphoric condition 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 Conclusion By 18 months of age infants interpret one as anaphoric to N’ and therefore represent NPs with a nested structure What does this imply???

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

Other possible interpretation of results… Experimentation Other possible interpretation of results… It could be the case that infants treat one as anaphoric to N° 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.

Control Experiment 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°) Example: “Do you see another bottle?” Adjective-Noun condition- children asked question that had adj-noun combination heard in familiarization (N’) Example: “Do you see another yellow bottle?”

Predictions and Results Control Experiment 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 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’ What found

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

Interpretation of results… Control Experiment 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

Discussion Learners just beginning to combine words already have a rich syntactic representation 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’ Support for nativism- but experimenters still acknowledge role of input END