l2 phonology fmri workshop -...

CAPSLAP L2 phonology fMRI workshop

Julius Fridriksson & Dirk den Ouden

University of South Carolina Dept. of Communication Sciences and Disorders

February 16th, 2012

What does Neuroimaging bring to the table?

Questions

• Most L2 neuroimaging research concerns learning and associated neural plasticity: – To what extent are neural representations separate

between L1 and L2 processing? – Do neural representations reflect L2 proficiency by

becoming more ‘native-like’? – Why can some L2 speakers reach ‘native-like’ proficiency,

while this appears to be impossible for others? – How are qualitative differences and similarities between

L1 and L2 reflected in neural activation patterns? • Is it only the non-native sound patterns that require support from

additional resources? • Do such resources seem language-related, or do they reflect more

general cognitive effort (attention, working memory, etc.)? – Which specific areas are involved?

Approaches

• Whole-brain scanning

– Often forces retrospective interpretation of findings • for example, relating findings in

unanticipated brain areas to previous studies that discuss processes supported by these areas.

• Region(s) of interest (ROI)

– Particular question, based on what is already known about the type of function(s) supported by a specific brain area.

Tan et al., 2011

Simmonds et al., 2011

A sample …

• Language comprehension (Dehaene et al., 1997; Jeong et al., 2007)

– L1 Left lateralized perisylvian network, stable; (late) L2 more variance across speakers, including right lateralization of activation

– Modulations dependent on linguistic distance between L1 and different L2s

• Lexical Retrieval/Naming (Liu et al, 2010) (Leonard et al., 2010)

– Increased activation in L2, during picture naming

– Recruitment of right-hemisphere in initial stages of L2 proficiency

• Syntactic processing (Kotz, 2009; Tolentino & Tokowizc, 2011; Stein et

al. 2006; Nauchi et al, 2009; Sakai et al., 2009)

– L2 proficiency is a driving factor

– Potential effects of structural (dis)similarity between languages

Reading

• Activity levels in LH caudate and fusiform regions in early age (10) is predictive of successful

acquisition of L2 reading skills (Tan et al, 2011). – LH caudate and fusiform regions may mediate language

control functions and resolve competition between L1 and L2, during learning.

Phonology

• Perception of sentence-level prosody (Chinese/English;

Gandour et al., 2007)

– “unitary neural system”, with possible task-related additional resource recruitment

• Greater activation in (bilateral) planum temporale & parietal operculum during L2 overt speech, compared to L1 (Simmonds et al., 2011)

• a “sensory-motor interface” • auditory language processing • implicated in dyslexia

• Also correlated with auditory (artificial) L2 learning (Newman-Norlund, 2006)

General

• Frontal areas show different L1 and L2 representation after late acquisition (Kim et al., 1997)

– Early acquisition: convergence – Convergence in Wernicke’s area, regardless of Age of Acquisition

• General, meta-analysis (Indefrey 2006): – reliably stronger activation during L2 processing found

(a) only task-specific in subgroups of L2 speakers and (b) within some, but not all regions that are also typically activated in

native language processing

• Age of Acquisition effects: mainly in LH IFG, modulated during syntactic processing, word generation, and sentence generation (Wattendorf & Festman, 2008)

IFG

Potential tasks for phonological experiments

• Rhyme judgment on visual stimuli

• Spelling judgment on auditory stimuli – E.g. “Are two words spelled the same, after the first vowel”

(used in kids, by James Booth)

• Visual lexical decision (Newman & Joanisse, 2011; Tan et al., 2011; Wilson et al., 2011))

• Overt/covert articulation (words: sparse scanning) – Picture naming (Liu et al., 2010)

– Connected overt speech (Simmonds et al., 2011)

• Living/nonliving semantic judgment (distractor task)

Demonstration Experiment

• Is there a difference between native and nonnative processing in high-proficiency speakers?

–Modulated by language, or is it structure-specific?

English phonology

Spanish phonology


• Is there a difference between native and nonnative processing in high-proficiency speakers?

–Modulated by language, or is it structure-specific?

• Syllable structure/phonotactic differences

– Spanish: • no sC-onset clusters

– station – estacion

• no word-final CC(CC) codas, and clusters rare in medial codas – e.g loanwords: record – [rekor]; film – [fíl.me]

– English: • restrictions on glides:

– *[pw] (puerta), *[trw] (trueco), *[plj] (pliego)


• Two high-proficiency bilinguals, English-Spanish and Spanish-English, perform task in English and in Spanish

– Stimuli include phonotactic structures that (1) comply with both languages, that are (2) native only to English and (3) native only to Spanish

• Task: Living/nonliving judgment on auditory stimuli

• Stimuli matched for length and lexical frequency

• Stimuli recorded by early bilingual (age 6) Spanish-English speaker (Panama Spanish; American English)


• 4 lists of words

– randomize order

– 4 blocks per condition

• each block has 2 or 3 living items

• Sound files recorded and edited (Audacity)


• Block design (for robustness within single subjects) – Auditory presentation – Left-hand button-press response

• only press for ‘living’ items, reducing the ‘motor noise’

• Full 2X2(X2) design – two participants: (1) Spanish L1, English L2; (2) English L1,

Spanish L2

• 10 3-second trials per 30-second block: 4 blocks per condition – split up into 2 ‘runs’ (of about 6 minutes each)

Spanish English

Exclusive phonology 40 (10 living/30 nonliving) 40 (10 living/30 nonliving)

Shared phonology 40 (10 living/30 nonliving) 40 (10 living/30 nonliving)


Spanish English



time

+ + + + + exclusive English

inclusive Spanish

exclusive English

inclusive English

exclusive Spanish

Exclusive English!


• “Contrasts” of interest (within participants):

1. Spanish vs. English / L1 vs L2

2. Exclusive vs. Shared phonology

3. For English L1 speaker: Spanish excl. vs. shared

(control: English excl. vs. shared)

4. For Spanish L1 speaker: English excl. vs. shared

(control: Spanish excl. vs. shared)

Spanish English



At the scanner

• Anatomical scan (T1): 7 minutes

• Two experimental blocks: 6 minutes

6 minutes

19 minutes

• This comes down to half an hour per participant

– placement in the scanner

– setting up the scans

Thanks

• Emily Garnett

• Paul Reed

• Victoria Sharpe

• Jessica Williams

• Lenora Hayes

McCausland Center for Brain Imaging

University of South Carolina

l2 phonology fmri workshop -...

Documents