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Brain Waves and Button Presses: The Role for Experiments in Theoretical Linguistics. Alec Marantz Department of Linguistics & Philosophy, MIT KIT/MIT MEG Joint Research Lab. Competence static representational

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Brain Waves and Button Presses: The Role for Experiments in Theoretical Linguistics

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Brain Waves and Button Presses: The Role for Experiments in Theoretical Linguistics

Alec Marantz

Department of Linguistics & Philosophy, MIT

KIT/MIT MEG Joint Research Lab


Competence

static

representational

accounts for generalizations about structures and relations between sentences and words

language knowledge

Performance

active

computational

accounts for reaction times and error rates in comprehension and production

language use

Competence vs. Performance?Standard View


Data are DataTheory of linguistic knowledge – the grammar – should be involved in an account of all data

  • Judgments of grammaticality

  • Judgments of meaning (e.g., synonymy, entailment)

  • Reaction times in lexical decision

  • Reaction times in phoneme monitoring

  • Amplitude of N400 response to content words


Non-issues in competence vs. performance I:Frequency

  • CAT PORCUPINE

  • Is frequency “part” of these representations?

  • (Font size would be proportional to word frequency and time to access/use these representations would be some function of frequency)


Non-issues in competence vs. performance II:Categorical distinctions in grammar

  • Categorical distinctions from grammatical representations do not imply categorical decisions, judgments, or behavior

  • *[N [Adj [N glori] os] ity]

  • [N [Adj [N glori] ous] ness]

  • Categorical grammatical/ungrammatical distinction along one linguistic dimension does not immediately imply categorical judgment from speakers.


New Competence/Performance Distinction:Dual Route Theories

  • Generative grammars instantiate a computational system that maps between sound and meaning

  • These grammars accurately describe speakers’ knowledge of the connection between sound and meaning

  • However, suppose speakers have alternative strategies (=computational systems) for connecting sound and meaning for particular “performance” needs (comprehension, production)?


Dual Route Theories…

  • raise the question:

    • What special data does a linguist have that allow him/her to develop a true account of linguistic computations independent of “strategies” used in language comprehension or production?

  • In practice:

    • Linguists must take “strategies” seemingly supported by “psycholinguistic” data as competing theories of linguistic computation

  • That is:

    • Data are data and the linguist is responsible for all the data


Impact of Experiments on Linguistic Theory

  • A symbolic importance, a reminder of the potential testability of competing analyses

  • A constraint on linguistic theory from what might be called the logical problem of language use

  • Clarification of the concrete mechanisms of language processing in the brain that allows straightforward interpretation of brain and behavioral data


KIT/MIT MEG Lab

Symbol of potential predictions of linguistic hypotheses


I placed a jar in Tennessee,

And round it was, upon a hill.

It made the slovenly wilderness

Surround that hill.

The wilderness rose up to it,

And sprawled around, no longer wild.

The jar was round upon the ground

And tall and of a port in air.

It took dominion every where.

The jar was gray and bare.

It did not give of bird or bush,

Like nothing else in Tennessee.

--Wallace Stevens

MEG as symbol: taming the slovenly linguistic wilderness


The “logical problem of language use”

  • Linguistic computations for structures that speakers use must be computable in real time and from the information available to speakers/listeners

  • Considerations of this “logical problem” support strong locality constraints on information dependencies in linguistic representations, for example


The more we know, the more we can discover

  • Mapping linguistic computation in time and in brain space increases the relevance of psycholinguistic and neurolinguistic experimentation for linguistic theory


MEG

  • Similar to EEG but measures the magnetic field around the electric current source (instead of electric potentials).


Magnetoencephalography (MEG) =

study of the brain’s magnetic fields

http://www.ctf.com/Pages/page33.html


Magnetoencephalography (MEG)

EEG

MEG

http://www.ctf.com/Pages/page33.html


Outgoing

Ingoing

Magnetoencephalography (MEG)

Distribution of magnetic field at 93 ms (auditory M100)

Averaged epoch of activity in all sensors overlapping on each other.


150-200ms M170

200-300ms M250

300-400ms M350

BEHAVIORAL RESPONSE (lexical decision)

400-500ms

200

[fT]

0

200

-100 0 100 200 300 400 500 600 700 [msec]

HBM 2003, poster 1345

Visual Word Recognition (Lexical Decision)


Activation

Competition

Selection

TURN

TURNIP

level of activation

TURF

TURTLE

resting level

time

Stimulus: TURN

M350

(i) 1st component sensitive to lexical factors (such as lexical frequency and sound probability)

(ii) not affected by form competition, e.g.

from phonological neighbors


Repetition

(i)

(ii)

Frequency

  • Stimuli that

  • speed up early lexical processing

  • but induce intense competition, delaying RT

  • elicit faster, not slower M350’s.

(Embick, Hackl, Shaeffer, Kelepir, Marantz, Cognitive Brain Research, 2001)

(Pylkkänen, Stringfellow, Flagg, Marantz, Biomag2000 Proceedings, 2000)

M350

(i) 1st component sensitive to lexical factors (such as lexical frequency)

(ii) not affected by competition


neighborhood density slows RT (post-M350 compe-tition)

sub-lexical probability speeds M350

*

*

*

*

n.s.

n.s.

n.s.

n.s.

Effect of sound probability/

neighborhood density (n=10)

(Pylkkänen, Stringfellow, Marantz, Brain and Language, 2002)


Auditory and visual M350 for S1

Auditory

Visual

RMS (all left hemisphere sensors)

M350 field pattern

Sagittal view

Sagittal view

M350 location with respect to auditory M100

A

P

A

P

M100

M350


Competition effects counteract morphological priming (in cross-modal priming)

  • gave-GIVEno priming

  • taught-TEACHyes priming

  • walked-WALKrobust priming


MEG Evidence for the morphological complexity of the English Irregular Past Tense

Linnaea Stockall, Priya Singh, Pranav Anand, Justin Fitzpatrick and Alec Marantz Dept. of Linguistics and Philosophy, MIT & KIT/MIT MEG Lab


Prediction:

  • gave-GIVE

  • taught-TEACH

    • M350 priming, followed by RT inhibition


Method

Stimuli:4 comparisons

  • Identity:ghost-ghost vs. trick-ghost

  • Irregulars

  • high form overlap:gave-give vs. plum-give

  • low form overlap:taught-teach vs. warp-teach

  • Orthographic Overlap: stiff-staffvs. clap-staff

    20 test and 20 control items per condition =

    320 prime-target pairs

    Plus 320 fillers (NW-NW, W-NW & NW-W)


Method

Design:

Visual-visual immediate priming

(see Pastizzo and Feldman 2002 )

prime

+

target

450 50 200 0 …2500ms

Duration of trial (ms)


Results

Behavioral Data (n=14)

**

*

*

n.s.


Results

Behavioral Data:

  • Significant priming for

    Identity condition (**p=0.0009)

    GAVE-GIVE vs. PLUM-GIVE(p=0.03)

  • Significant inhibition for

    STIFF-STAFF vs. CLAP-STAFF (p=0.01)

  • No reliable effect for

    TAUGHT-TEACH vs. WARP-TEACH (p=0.21)

    (but trend towards inhibition)


Results

M350 Priming (advantage of prime condition over control) (n=8)

*

*

*

n.s.


Results

MEG Data:

  • Significant priming for :

    Identity condition (*p=0.01)

    GAVE-GIVE vs. PLUM-GIVE(*p=0.05)

    TAUGHT-TEACH vs. WARP-TEACH (*p=0.04)

  • No reliable effect for:

    STIFF-STAFF vs. CLAP-STAFF (p=0.13)

    But trend towards priming


What do these results say about the kind of stem allomorphy involved in English irregular verbs?

  • The observed form competition requires that allomorphs compete for recognition – are these:

    • Stored allomorphs not explicitly related to each other?

    • Allomorphs derived via special morpholexical rules?

    • Allomorphs derived via morphologically triggered phonological rules?

      Brain data provides new empirical texture to these questions.

      Differential time-course of stem activation and form competition allows one to distinguish levels and types of stored information.


HBM 2003, poster 1345

Magnetoencephalographic indices of the effects of morphological family frequency

Alec Marantz

Department of Linguistics and Philosophy, KIT/MIT MEG Laboratory

Massachusetts Institute of Technology

Liina Pylkkänen

Department of Linguistics/ Center for Neuromagnetism

New York University


Same number of derivates

High frequency derivatives

Low frequency derivatives

- ist –ize -ism

- ic –ize –ism

terror

magnet

Matched for surface frequency

Effect of lexical frequency

  • High frequency words are processed faster than low frequency words.

  • Prediction of decompositional theories of morphology: cumulative root frequency effects.


Should be faster due to high cumulative root frequency

Effect of lexical frequency

  • High frequency words are processed faster than low frequency words.

  • Prediction of decompositional theories of morphology: cumulative root frequency effects.

Same number of derivates

High frequency derivatives

Low frequency derivatives

- ist –ize -ism

- ic –ize –ism

terror

magnet

Matched for surface frequency


Cumulative root frequency effects for inflection

  • Response times to a noun depend on the cumulative frequency of the singular and plural (Schreuder & Baayen, JML, 1997)

    CAT

    CATS


  • Family size

LOW

HIGH

- ic –ity –ify –head –test –washed

- ist

acid

diary

But NO cumulative root frequency effects for derivation

Schreuder & Baayen (1997):

  • Family frequency

HIGH

LOW

Family frequency does not affect lexical decision times.

- ist –ize -ism

- ic –ize –ism

[S&B: Therefore, no decomposition in derivation.]

terror

magnet

High family size speeds up lexical decision times.

S&B: this is a late post-lexical effect.


Activation

Competition

Selection

TURN

TURNIP

level of activation

TURF

TURTLE

resting level

time

Stimulus: TURN

M350

(i) 1st component sensitive to lexical factors (such as lexical frequency)

(ii) not affected by form competition


LOTS OF PHONOLOGICAL NEIGHBORS

FEWER PHONOLOGICAL NEIGHBORS

HBM 2003, poster 1345

M350: not sensitive to interlexical or allomorphic form competition

**

**

SUBLEXICAL FREQUENCY EFFECT

COMPETITION EFFECT


RT

RT

slow-down due to competition from highly frequent family members

speed-up due to cumulative root frequency

HBM 2003, poster 1345

Hypothesis

  • High morphological family frequency is associated with:

= null behavioral effect

BUT morphological competition should be distinguishable from phonological competition


Same number of derivates

High frequency derivatives

Low frequency derivatives

- ist –ize -ism

- ic –ize –ism

Matched for surface frequency

HBM 2003, poster 1345

Materials: 2 categories of singular nouns

terror

magnet

  • Task: Lexical decision


100%

75%

50%

25%

HBM 2003, poster 1345

M350 source analysis

  • Equivalent current dipole analysis

  • Latencies and amplitudes measured at points where the source amplitude reached 25%, 50%, 75% and 100% of the maximum source strength.


n.s.

High freq.

Low freq.

HBM 2003, poster 1345

Results: Lexical decision times (n = 10)No behavioral culmulative root frequency effect(trend toward inhibitory effect of higher frequency)


High family frequency

HBM 2003, poster 1345

Results: M350 (S1)


High family frequency

HBM 2003, poster 1345

Results: M350 (S1)


High family frequency

Extra processing load at the M350

HBM 2003, poster 1345

Results: M350 (S1)

Low family frequency

  • Morphological competition at the M350


HBM 2003, poster 1345

Results: M350 amplitude (n=10)


HBM 2003, poster 1345

Results: M350 amplitude (n=10)

*


fine

lie

- ist –ize -ism

loin

pine

TERROR

LINE

lane

like

light

lime

nine

fine

lie

loin

pine

LINE

lane

like

light

lime

nine

1. Difference in the time course of competition

High frequency morphological family

High density phonological neighborhood (frequency-weighted)

  • Relationship between target and competitors qualitatively different: difference is due to morphology.

DECOMPOSITION

  • Difference is due to the different phonological and/or semantic properties of the competitors.

terrorism

TERROR

NO DECOMPOSITION

DUAL ROUTE

THEORY

(DECOMPOSITION

FOR REGULARINFLECTION)

terrorist

terrorize


fine

lie

loin

pine

LINE

lane

like

light

lime

nine

1. Difference in the time course of competition

  • Non-decompositional account also predicts interference effects in priming for pairs such as TERRORISM – TERROR.

  • BUT this is completely unsupported by data – effect is robustly facilitory (e.g. a-d).

  • Difference is due to the different phonological and/or semantic properties of the competitors.

terrorism

TERROR

NO DECOMPOSITION

terrorist

terrorize

  • (a) Marslen-Wilson, W. D., Tyler, L., Waksler, R., & Older, L. (1994). Morphology and meaning in the English mental lexicon. Psychological Review 101, 3-33.

  • (b)Pylkkänen, L. Stringfellow, A., Gonnerman, L., Marantz, A. 2002. Magnetoencephalographic indices of identity and similarity in lexical access. In preparation.

  • Gonnerman, L. 1999, Morphology and the lexicon: exploring the semantics-phonology interface, PhD thesis, University of Southern California.

  • Rastle, K., Davis, M., Marslen-Wilson, W., & Tyler, L.K. (2000). Morphological and semantic effects in visual word recognition: A time course study. Language and Cognitive Processes, 15, 507-538.


fine

lie

- ist –ize -ism

loin

pine

TERROR

LINE

lane

like

light

lime

nine

1. Difference in the time course of competition

High frequency morphological family

High density phonological neighborhood (frequency-weighted)

DECOMPOSITION

  • Competition between morphological family members appears to precede competition between phonological neighbors.

  • An account of the phenomenon needs to make a distinction between morphological and phonological competitors.


Early morphological parsing/ segmentation

Lexical access

HBM 2003, poster 1345

Conclusion

Decomposition

Morphological competition effects

Phonological competition effects


Summary

  • A misunderstanding of the competence/performance distinction has perhaps led to the underutilization within linguistics of evidence from experiments

  • Any retreat from obvious processing implications of linguistic theories involves a “dual” or “multi-route” claim that there might be more than one computational path to the connection between sound and meaning

  • Supporting such multi-route theories would put extreme pressure on linguists to explain the special source of data for privileged “linguistic” computation

  • Rather, any processing strategies proposed in the literature should be taken as competing linguistic theories and refuted via standard theory comparison/linguistic argumentation


Comfortable position for linguistics, represented by the research of Uil-OTS

  • Take every bit of linguistic theory as a claim about necessary computation in linguistic performance (no independent strategies for sound/meaning connections; no multiple routes to linguistic representations)

  • Take every bit of behavioral and brain data as potentially decisive between competing linguistic hypotheses


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