Transcript SYNTAX 5 ON-LINE PROCESSING DAY 34 – NOV 15, 2013 Brain & Language LING 4110-4890-5110-7960 NSCI 4110-4891-6110 Harry Howard Tulane University.

SYNTAX 5
ON-LINE PROCESSING
DAY 34 – NOV 15, 2013
Brain & Language
LING 4110-4890-5110-7960
NSCI 4110-4891-6110
Harry Howard
Tulane University
11/15/13
Brain & Language - Harry Howard - Tulane University
2
Course organization
• The syllabus, these slides and my recordings are
available at http://www.tulane.edu/~howard/LING4110/.
• If you want to learn more about EEG and neurolinguistics,
you are welcome to participate in my lab. This is also a
good way to get started on an honor's thesis.
• The grades are posted to Blackboard.
11/15/13
REVIEW
Brain & Language - Harry Howard - Tulane University
3
11/15/13
Brain & Language - Harry Howard - Tulane University
Linguistic model, Fig. 2.1 p. 37
Discourse model
Sentence level
Word level
Syntax
S
E
M
A
N
T
I
C
S
Sentence prosody
Morphology
Word prosody
Segmental phonology
production
Segmental phonology
perception
Articulatory phonetics
Speech motor control
Acoustic phonetics
Feature extraction
INPUT
4
11/15/13
Brain & Language - Harry Howard - Tulane University
My favorite attachment ambiguity
• One morning I shot an
elephant in my
pajamas.
• What an elephant was
doing in my pajamas,
I'll never know.
• I [[shot an elephant] in
my pajamas]
• I shot an [[elephant] in
my pajamas]
5
11/15/13
Brain & Language - Harry Howard - Tulane University
6
Garden path sentences
1. The old man the boat.
2. The man whistling tunes pianos.
3. The cotton clothing is made of grows in Mississippi.
4. The complex houses married and single soldiers and
their families.
5. The author wrote the novel was likely to be a bestseller.
6. The tomcat curled up on the cushion seemed friendly.
7. The horse raced past the barn fell.
11/15/13
Brain & Language - Harry Howard - Tulane University
7
SENTENCE
COMPREHENSION AND
SYNTACTIC PARSING
Ingram I, §13 On-line processing, working memory and
modularity
11/15/13
Brain & Language - Harry Howard - Tulane University
8
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
11/15/13
Brain & Language - Harry Howard - Tulane University
9
Two types of processing
on-line
off-line
• Happens in real time.
• Happens after the fact.
• Instructions for an
• Instructions for an
experiment to test it:
experiment to test it:
• You will read a sentence,
• You will read a sentence.
one word at a time.
• Push a key after each word.
• Point to the picture that
describes it best.
11/15/13
Brain & Language - Harry Howard - Tulane University
10
Working memory
• How would you solve this arithmetic problem?
• 1+1+1=?
• (1 + 1) + 1 = ?
• 2+1=3
• So you need to store the second half of the problem as you calculate
the first half.
• The prototypical example is keeping a telephone number in
mind as you dial it:
• 862-3417
• This sort of storage is known as working memory, and has
been variously characterized as:
• a scratch pad,
• a temporary work space,
• a buffer.
11/15/13
Brain & Language - Harry Howard - Tulane University
11
Working memory span or capacity
• The amount of material that you can keep on your
‘scratch pad’ is known as your working memory span or
capacity.
• How much is it?
• Miller’s number: 7 ± 2
• It varies a little from person to person and even from
domain to domain in the same person.
• That’s the meaning of the “± 2”
• Working memory span can be impaired in brain injury.
• It has recently been shown to be correlated with fluid intelligence.
11/15/13
Brain & Language - Harry Howard - Tulane University
12
Short-term memory
• There is also something called short-term memory, which
I can never understand how it is different from working
memory.
11/15/13
Brain & Language - Harry Howard - Tulane University
13
Fluid vs. crystallized intelligence
• Fluid (Gf) and crystallized (Gc) intelligence are factors of
general (G) intelligence.
• Fluid intelligence is the capacity to think logically, recognize
patterns, and solve problems in novel situations.
• Crystallized intelligence is the ability to use skills, knowledge, and
experience. It improves somewhat with age, as experiences tend to
expand one's knowledge.
11/15/13
Brain & Language - Harry Howard - Tulane University
14
Back to syntax
• Parsing a sentence also exercises working memory.
• [S [NP a cat] [VP is [PP on [NP the couch]]]]
S
VP
NP
a cat
V
is
PP
on the couch
11/15/13
Brain & Language - Harry Howard - Tulane University
15
One or two working memories?
• There is some debate over whether the working memory
needed for parsing is part of a general purpose working
memory or constitutes its own specialized store of working
memory.
• Evidence for the latter
• Some patients who share severe deficits of general purpose working
memory as assessed by attention span tests are still able to
understand complex spoken sentences.
• Individual differences in working memory are usually not implicated in
on-line language understanding.
• HH: does this mean that language is more an aspect of crystalized
intelligence than fluid intelligence?
• Evidence for the former
• Individual differences in working memory are implicated in strategies
for understanding complex spoken sentences.
• Ingram says it’s a tie.
• I am going to try to test this in the next experiment.
11/15/13
Brain & Language - Harry Howard - Tulane University
16
Some relevant tasks
• Sentence processing
• Self-paced reading:
• A sentence is presented as a series of words on a computer monitor,
and the subject presses a key on the keyboard after each word.
• The horse raced past the barn fell.
• Working memory
• Attention span
• How many digits can the subject remember and recall in normal or
reverse sequence?
• Verbal working memory ~ reading/listening span
• The subject reads/hears a series of sentences presented as a block.
• How many sentences can the subject recall the last word of?
• This span correlates highly with verbal SAT scores.
11/15/13
Brain & Language - Harry Howard - Tulane University
17
Syntax vs. pragmatics: Ferreira & Clifton
Modified from Ingram p. 271; see Figure 13.1
Sentence
Relative
clause
Subject
Latency at by
1. The evidence examined by
the lawyer shocked the jury.
reduced
inanimate
same as 3
unreduced
inanimate
quicker than 1
reduced
animate
same as 1
unreduced
animate
quicker than 3
2. The evidence that was
examined by the lawyer
shocked the jury.
3. The defendant examined by
the lawyer shocked the jury.
4. The defendant that was
examined by the lawyer
shocked the jury.
The fact that there is no garden path at by in (3) shows that
syntax can perform the parse without access to pragmatics.
11/15/13
18
Brain & Language - Harry Howard - Tulane University
Just & Carpenter
see Figure 13.2
Low reading span
Latency at by
High reading span
Latency at by
unreduced
relative
clause
reduced
relative
clause
unreduced
relative
clause
reduced
relative
clause
inanimate
subject
~450 ms
~500 ms
inanimate
subject
~350 ms
~400 ms
animate
subject
~450 ms
~500 ms
animate
subject
~425 ms
~475 ms
Same as before: no competition
from pragmatics to confuse (and
slow down) syntactic parse
Different: latency is indeed longer
in bottom cell than top cell of
reduced relative clause >
pragmatics creates a garden path
11/15/13
Brain & Language - Harry Howard - Tulane University
19
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).
11/15/13
Brain & Language - Harry Howard - Tulane University
20
NEXT TIME
Q10
Continue with Ingram §13, On-line processing, working
memory and modularity