TAKING MORPHOLOGY SERIOUSLY: MEG STUDIES OF MORPHOLOGICAL - - PowerPoint PPT Presentation

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TAKING MORPHOLOGY SERIOUSLY: MEG STUDIES OF MORPHOLOGICAL REPRESENTATIONS Laura Gwilliams & Alec Marantz 17th International Morphology Meeting | Vienna | February 18th 2016 1 TODAYS QUESTIONS 1. What is represented? 2. How are

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TAKING MORPHOLOGY SERIOUSLY: MEG STUDIES OF MORPHOLOGICAL REPRESENTATIONS

Laura Gwilliams & Alec Marantz

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17th International Morphology Meeting | Vienna | February 18th 2016

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TODAY’S QUESTIONS

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  • 1. What is represented?
  • 2. How are representations formed?
  • 3. How are representations accessed?
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MAGNETOENCEPHALOGRAPHY (MEG)

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MAGNETOENCEPHALOGRAPHY (MEG)

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MAGNETOENCEPHALOGRAPHY (MEG)

Amplitude (dSPM)

Average

Time (ms)

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MAGNETOENCEPHALOGRAPHY (MEG)

Amplitude (dSPM) Linguistic Variable

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MAGNETOENCEPHALOGRAPHY (MEG)

Amplitude (dSPM) Linguistic Variable + + + + + + + + + + + + + + + + + + + + + +

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EXPERIMENT 1: WHEN AND WHERE TO LOOK

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Gwilliams, Lewis & Marantz (In Press)

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EXPERIMENT 1 - WHEN AND WHERE TO LOOK

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Vinckier et al., 2007

less wordlike more wordlike

GRAVEL AVONIL QUMBSS QOADTQ JZWYWK

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FUNCTIONAL LOCALISER

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Gwilliams, Lewis & Marantz (In Press)

iv)#Four-element# 1# 24# Symbols# ii)#One-element#

Mini-Experiment “Real” Experiment

free stem bound stem bookable durable perishable equable predictable hospitable printable numerable

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FUNCTIONAL LOCALISER

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Gwilliams, Lewis & Marantz (In Press)

iv)#Four-element# 1# 24# ii)#One-element# iv)#Four-element# 1# Symbols# ii)#One-element#
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APPLYING FUNCTIONAL LOCALISER

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Gwilliams, Lewis & Marantz (In Press)

Orthographic Morphological

iv)#Four-element# 1# 24# ii)#One-element# iv)#Four-element# 1# Symbols# ii)#One-element#
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EXPERIMENT 1 - TAKE AWAY

➤ Orthography: ~140 ms in the posterior temporal lobe ➤ Morphology: ~170 ms in the anterior temporal lobe ➤ Successfully created a localiser for these two streams of

processing

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EXPERIMENT 2: REPRESENTATIONS OF NON-EXISTENT STEMS

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Gwilliams & Marantz (In Prep.)

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“

To be recognized as a [stem] morpheme, a form must either (1) occur as a free form, making up a complete word, or (2) occur, with the same meaning, in more than one word.

  • R.M.W. Dixon
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Making New Words, 2014: 3

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➤ Copious evidence that:

CORNER

BACKGROUND & QUESTION

FARMER FARM + ER CORNER CORN + ER

➤ What is driving this effect?

presence of an isolatable stem morpheme visual form of a suffix morpheme congruent grammar

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see Rastle & Davis, 2008 for a review

BROTHEL ≠ BROTH + EL

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QUESTION

LEAKAGE BROTHER EXCURSION WINTER

  • isolatable stem, + congruent grammar
  • isolatable stem, - congruent grammar

+ isolatable stem, + congruent grammar + isolatable stem, - congruent grammar

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“to explode” “explosion” “to excurse” “excursion” “to bake” “baker” * “to wint” “winter”

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➤ Lexical decision task ➤ Ran “morphology localiser” to select ROI ➤ 24 native English participants

SETUP

LEAKAGE BROTHER EXCURSION WINTER

  • isolatable stem, + congruent grammar
  • isolatable stem, - congruent grammar

+ isolatable stem, + congruent grammar + isolatable stem, - congruent grammar 53 items per condition

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RESULTS

➤ Hypotheses:

  • 1. Presence of a suffix morpheme
  • 2. Presence of an isolatable stem morpheme
  • 3. Presence of congruent syntax
  • 4. Combination: 2 or 3
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CONDITION suffix isolatable stem congruent grammar combination 2 or 3 leakage 1 1 1 1 brother 1 1 1 excursion 1 1 1 winter 1

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RESULTS

➤ Analysis:

➤

Mixed effects regression model

➤

Ran in localised “morphology” region

➤

Coded as binary variables

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CONDITION suffix isolatable stem congruent grammar combination 2 or 3 leakage 1 1 1 1 brother 1 1 1 excursion 1 1 1 winter 1

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RESULTS

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CONDITION suffix isolatable stem congruent grammar combination 2 or 3 leakage 1 1 1 1 brother 1 1 1 excursion 1 1 1 winter 1

t = 2.15, p = .03 t = 1.06, p = .105 p > .5

➤ Analysis:

➤

Mixed effects regression model

➤

Ran in localised “morphology” region

➤

Coded as binary variables

not significant approaching significance

significant

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RESULTS

➤ Transition probability (TP) as an index of decomposition:

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LEAK EXCUR- WINT-

  • ING
  • S
  • AGE

BROTH

  • S
  • ER
  • SION
  • ER
  • ER

TP < 1 TP < 1 TP = 1 TP = 1

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RESULTS

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“excursion” “winter”

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“

To be recognized as a [stem] morpheme, a form must either (1) occur as a free form, making up a complete word, or (2) occur, with the same meaning, in more than one word.

  • R.M.W. Dixon
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Making New Words, 2014: 3

EXPERIMENT 2 - TAKE AWAY

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“

To be recognized as a [stem] morpheme, a form must either (1) occur as a free form, making up a complete word, or (2) occur, with the same meaning, in more than one word.

  • R.M.W. Dixon
25

Making New Words, 2014: 3

EXPERIMENT 2 - TAKE AWAY

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“

To be recognized as a [stem] morpheme, a form must either (1) occur as a free form, making up a complete word, or (2) occur [within a complex word with grammatical wellformedness].

  • R.M.W. Dixon
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Making New Words, 2014: 3

EXPERIMENT 2 - TAKE AWAY

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EXPERIMENT 3: REPRESENTATIONS OF NON-LINEAR ROOTS

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Gwilliams & Marantz (2015)

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BACKGROUND

➤ In semitic languages such as Arabic and Hebrew, morphemes

are arranged in an interleaved manner:

K A T A B A

root morpheme ktb pattern morpheme

  • a-a-a
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QUESTION

➤ Are Arabic words processed through their constituent

morphemes, or as un-analysed wholes?

K A T A B A

root morpheme ktb pattern morpheme

  • a-a-a
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QUESTION

➤ The superior temporal gyrus is sensitive to how expected it is

for a sound to occur within a word

➤ We utilised this sensitivity to determine what morphological

constituents are activated during processing

K A T A B A K T B

p( B | KATA) p( B | KT)

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QUESTION

➤ The superior temporal gyrus is sensitive to how expected it is

for a sound to occur within a word

➤ We utilised this sensitivity to determine what morphological

constituents are activated during processing

K A T A B A K T B

frequency( KATAB) frequency(KATA) frequency( KTB) frequency(KT)

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QUESTION

➤ The superior temporal gyrus is sensitive to how expected it is

for a sound to occur within a word

➤ We utilised this sensitivity to determine what morphological

constituents are activated during processing

K A T A B A K T B

linear surprisal =

  • log(p( B | KATA))

morphological surprisal =

  • log(p( B | KT))
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linear surprisal =

  • log(p( B | KATA))

morphological surprisal =

  • log(p( B | KT))
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Morphological Surprisal Linear Surprisal

MATERIALS

➤ 280 words with a CVCVCV structure

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QUESTION

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/ð/ /ɒ/ /ʒ/ /i/ /ɹ/ /a/

Correlation Strength Time (ms) surprisal 1 surprisal 2

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RESULTS

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/ð/ /ɒ/ /ʒ/ /i/ /ɹ/ /a/

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EXPERIMENT 3 - TAKE AWAY

➤ Spoken word processing in an understudied language such as

Arabic also shows morpheme specific processing

➤ Supports a morphological-driven theory of spoken word

comprehension rather than a model that assumes linear processing of phonemes (e.g., the cohort model)

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TODAY’S ANSWERS

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  • 1. What is represented?
  • 2. How are representations formed?
  • 3. How are representations accessed?

Root and stem morphemes. Through the recognition of a represented stem across both visual and auditory modalities. Dependant upon grammatical wellformedness

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TODAY’S ANSWERS

➤ Data from neurophysiological techniques allow us to inform

and adjudicate between different theoretical models

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Experimental approach informs theory Theory informs experimental approach

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THANK YOU, DANKE!

References: Gwilliams, L., & Marantz, A. (2015). Non-linear processing of a linear speech stream: The influence of morphological structure on the recognition of spoken Arabic words. Brain and language, 147, 1-13. Gwilliams, Lewis & Marantz (In Press). Functional characterisation of letter-specific responses in time, space and current polarity using magnetoencephalography. NeuroImage. Lewis, G., Solomyak, O., & Marantz, A. (2011). The neural basis of obligatory decomposition of suffixed words. Brain and language, 118(3), 118-127. Rastle, K., & Davis, M. H. (2008). Morphological decomposition based on the analysis of orthography. Language and Cognitive Processes, 23(7-8), 942-971. Solomyak, O., & Marantz, A. (2009). Lexical access in early stages of visual word processing: A single-trial correlational MEG study of heteronym recognition. Brain and language, 108(3), 191-196. Solomyak, O., & Marantz, A. (2010). Evidence for early morphological decomposition in visual word recognition. Journal of Cognitive Neuroscience, 22(9), 2042-2057. Stockall, L., & Marantz, A. (2006). A single route, full decomposition model of morphological complexity: MEG evidence. The Mental Lexicon, 1(1), 85-123. Tarkiainen, A., Helenius, P ., Hansen, P . C., Cornelissen, P . L., & Salmelin, R. (1999). Dynamics of letter string perception in the human occipitotemporal cortex. Brain, 122(11), 2119-2132. 39

contact: laura.gwilliams@nyu.edu

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RESULTS

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Time (ms) Amplitude of Response