SYNTAX 6 NOV 20, 2015 – DAY 36 Brain & Language LING 4110-4890-5110-7960 NSCI 4110-4891-6110 Fall 2015

SYNTAX 6NOV 20, 2015 – DAY 36

Brain & LanguageLING 4110-4890-5110-7960NSCI 4110-4891-6110Fall 2015

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Course organization• Schedule:

• http://www.tulane.edu/~howard/BrLg/t1-Intro.html#schedule-of-topics

• Today's chapter:• http://www.tulane.edu/~howard/BrLg/t19-aIFG.html

• Fun with https://www.facebook.com/BrLg15/• Quiz on Monday will be in class & on Blackboard.

11/20/15 Brain & Language - Harry Howard - Tulane University

http://www.tulane.edu/~howard/BrLg/t1-Intro.html%23schedule-of-topics

http://www.tulane.edu/~howard/BrLg/t1-Intro.html%23schedule-of-topics

http://www.tulane.edu/~howard/BrLg/t19-aIFG.html

https://www.facebook.com/BrLg15/

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GradesQ1 Q2 Q3 Q4 Q5 Q6 Q7

MIN 6 5 5 4 7 3 4AVG 9.0 8.8 8.8 8.4 9.2 7.5 8.7MAX 10 10 10 10 10 10 10


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COMBINATORIAL NET 2


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The lexical interface


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Models of sentence processing

Traditional generative model

• A separate mental module parses sentences just like we just did.

• Lexical access happens first.• Then one syntactic hypothesis

is considered at a time.• There is no influence of

meaning.

More recent interactive model

• There is no separate module for parsing

• Lexical access, syntactic structure assignment, and meaning assignment happen at the same time (in parallel).

• Several syntactic hypotheses can be considered at a time.


How to decide?On-line processing

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Two types of processing

on-line

• Happens in real time.• Instructions for an

experiment to test it:• You will read a sentence,

one word at a time. • Push a key after each word.

off-line

• Happens after the fact.• Instructions for an

experiment to test it:• You will read a sentence.• Point to the picture that

describes it best.


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The working memory needed for parsing …

… is part of a general purpose working memory

• Individual differences in working memory are implicated in strategies for understanding complex spoken sentences.

… constitutes its own specialized store of working memory.

• Some patients who share severe deficits of general purpose working memory are still able to understand complex spoken sentences.

• Individual differences in working memory are usually not implicated in on-line language understanding.


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Why?• ‘Cognitive capacity’

• Low span readers only have enough capacity to process syntactic cues; nothing is left over to process pragmatics => modular processing (syntax first).

• High span readers have enough capacity to process syntactic cues and pragmatics => interactive processing (all cues considered simultaneously).


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Center embedding


9) The rat the cat hunted nibbled the cheese.

The rat which the cat hunted nibbled the cheese.

10) The rat the cat the dog chased hunted nibbled the cheese.

The rat which the cat which the dog chased hunted nibbled the cheese.

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How might this be processed?


thematic role for ‘the rat’

thematic role for ‘the cat’

thematic role for ‘the dog’

The parser encounters …the rat > look for a predicate to supply a thematic role …

the cat > wait, put the previous search on hold & look for another predicate to supply a thematic role …the dog > wait, put the previous search on hold & look for yet another predicate to supply a thematic role …

Ok, now I am lost.

push-down stack

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‘Edge’ embedding does not create this problem


i) The dog chased the cat that hunted the rat that nibbled the cheese.

ii) The dog that chased the cat that hunted the rat that nibbled the cheese was a dachshund.

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Interim conclusion• The limit on center embedded is 2.• Given that Miller’s number is much larger, it would appear

that there is a working memory specialized for parsing.


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Ockham’s razor, simplicity, economylex parsimoniae

• Ockham’s razor is a principle that generally recommends selecting from among competing hypotheses the one that makes the fewest new assumptions.

• Einstein-ish: “Make things as simple as possible, but not simpler.”


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Filler-gap constructionsthough the gap is also called a trace

• How to get rid of the leprechaunsa. Mary bought a book for John.b. Which booki did Mary buy ____i for John?c. John asked Mary about a student.d. Which studenti did John ask Mary about ____i ?


SYNTAX 4Sentence comprehension and syntactic parsing

11/20/15 Brain & Language - Harry Howard - Tulane University 16

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Cross-modal priming & trace reactivationsentence presented auditorily; prime & probe visually


16) Which booki did the harassed parent almost purchase ti for her child?

prime

probe:library/vehicle

faster for related same for both faster for related

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Gaps/traces in relative clauses• The dog chased the cat.• Subject relative clause

• The dog that chased the cat … =• The dogi that ti chased the cat …

• Object relative clause• The cat that the dog chased … =• The cati that the dog chased ti …

• Which one should be harder to process?• The object relative clause, because the relationship between the

real filler (the cat) and the gap has to ignore the potential filler (the dog).


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Self-paced reading & subject-object• The data: reading time for us20a) My brother wanted to know if Ruth will bring us home to Mom at Xmas.20b) My brother wanted to know who will bring us home to Mom at Xmas. =20b) My brother wanted to know whoi ti will bring us home to Mom at Xmas.20c) My brother wanted to know who Ruth will bring us home to at Xmas. = 20c) My brother wanted to know whoi Ruth will bring us home to ti at Xmas.

• Which one should be slowest?• (20c) because us is a possible site for the gap/trace of who.


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NEURAL IMAGING & ON-LINE SENTENCE PROCESSING


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Dipoles, 3


Brain & Language - Harry Howard - Tulane University 22

Result of electrical currents: EEG

11/20/15

Brain & Language - Harry Howard - Tulane University 23

Scalp EEG• Scalp EEG is collected from tens to hundreds of electrodes positioned on different locations at the surface of the head.

• EEG signals (in the range of millivolts) are amplified and digitalized for later processing.

11/20/15

The 10-20 system• The "10" and "20" refer to the fact that the actual distances between adjacent electrodes are either 10% or 20% of the total front-back or right-left distance of the skull.

• Each site has a letter to identify the lobe and a number to identify the hemisphere location. The letters F, T, C, P and O stand for Frontal, Temporal, Central, Parietal, and Occipital, respectively.

• Note that there exists no central lobe, the "C" letter is only used for identification purposes only.

• A "z" (zero) refers to an electrode placed on the midline.

• Even numbers (2,4,6,8) refer to electrode positions on the right hemisphere, whereas odd numbers (1,3,5,7) refer to those on the left hemisphere.

• Two anatomical landmarks are used for the essential positioning of the EEG electrodes: first, the nasion which is the point between the forehead and the nose; second, the inion which is the lowest point of the skull from the back of the head and is normally indicated by a prominent bump.


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Semantic vs. syntactic ERPs• The data

a. The boat sailed down the river and sank.b. The boat sailed down the river and ate.c. The boat sailed down the river sank.

• How would you characterize these sentences?a. well-formedb. semantically anomalousc. syntactically anomalous


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ERPs to last verb in sentence


What does the scale mean?

Where does the dashed line diverge most from the solid line?

Where does the dotted line diverge most from the solid line?

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What do they do?• N400

• A temporarily localized increase in processing load caused by a discrepancy between the meaning of a word and its sentential context.

• P600• A sustained effort to reinterpret or re-parse a garden path

sentence.• However, these two may be too slow to reflect modular

lexical or syntactic processing.• So lets look at a faster ERP.


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The early left anterior negativityN150 or ELAN


Basic flaws in phrase structure:The shirt was on the hanger.The shirt was ironed.*The shirt was on ironed.

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Modular vs. interactive processing

English example(orig. German)

Phrase structure obeyed

Argument structure obeyed

N150 N400 P600

The old cat slept in the garden and … ✔ ✔ -- -- --

The cat old slept in the garden and … ✖ ✔ ✔ ✖ ✔The old cat slept the garden and … ✔ ✖ ✖ ✔ ✔The cat old slept the garden and … ✖ ✖ ✔ ✖ ✔


Modular: an error found early could turn off additional processing. Interactive: errors should add up.

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Final project• Improve a Wikipedia article about any of the topics

mentioned in class or any other topic broadly related to neurolinguistics.

• Write a short essay explaining what you did and why you did it.

• Print the article before you improve it, highlighting any subtractions.

• Print the article after you improve it, highlighting your additions.


NEXT TIMEP10 on Blackboard & in classMore syntax


Documents

SYNTAX 6 NOV 20, 2015 – DAY 36 Brain & Language LING 4110-4890-5110-7960 NSCI 4110-4891-6110 Fall 2015