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
Demonstration Experiment
• 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)
Demonstration Experiment
• 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)
Demonstration Experiment
• 4 lists of words
– randomize order
– 4 blocks per condition
• each block has 2 or 3 living items
• Sound files recorded and edited (Audacity)
Demonstration Experiment
• 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)
Demonstration Experiment
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)
time
+ + + + + exclusive English
inclusive Spanish
exclusive English
inclusive English
exclusive Spanish
Exclusive English!
Demonstration Experiment
• “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
Exclusive phonology 40 (10 living/30 nonliving) 40 (10 living/30 nonliving)
Shared phonology 40 (10 living/30 nonliving) 40 (10 living/30 nonliving)
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