1st A' GUIORA ANNUAL ROUNDTABLE CONFERENCE IN THE COGNITIVE NEUROSCIENCE OF LANGUAGE: THE COGNITIVE

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1st A. GUIORA ANNUAL ROUNDTABLE CONFERENCEIN
THE COGNITIVE NEUROSCIENCE OF LANGUAGE THE
COGNITIVE NEUROSCIENCE OF L2ANijmegen, September
20, 2005 Age and L2AAn Overview

• David Birdsong
• University of Texas
• Visitor MPI-Nijmegen

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ACKNOWLEDGMENTS

• Organizers and Steering Committee of the
  Roundtable Conference Series
• Language Learning
• Max Planck Institute for Psycholinguistics

3
Preliminaries

• Overview (selective) of facts and issues relating
  to age and L2A
• Theory Evidence Methodology
• L2A end-state data
• Behavioral brain-based evidence
• L2 attainment L2 processing

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Organization

• I. Age and Nativelike Attainment in L2A
• II. Interpreting Age-Related Effects
• III. The Aging Brain and L2A
• IV. The Nature of Age Effects

5
Terminology

• gt Ultimate attainment ? nativelikeness
• attainment at end state/asymptote
• gt Nativelikeness experimental performance like
  that of native controls
• gt AoA Age of Acquisition/Arrival (immersion in
  L2 context)

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I. Age and Nativelike Attainment in L2A
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Age of Acquisition/Arrival (AoA) and
nativelikeness received views

• Bley-Vroman (1989 44) Insignificant incidence
  of nativelikeness in late L2A ineluctable
  failure Fossilization Fundamental Difference
  Hypothesis
• Johnson Newport (1989 255) for AoA gt 15
  later AOA determines that one will not become
  nativelike or near-nativelike in a language
  CPH/L2A

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Age of Acquisition/Arrival (AoA) and
nativelikeness received views

• Hyltenstam Abrahamsson (2003 575) If we look
  at overall L2 proficiency we will find that
  perfect proficiency and absolute nativelike
  command of an L2 may in fact never be possible
  for any late learner
• Deficient language-learning mechanism

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Nativelikeness in late L2A

• 1. Not typical, but not rare
• 20 studies / 13 years gt3 - 45 of subjects
  perform like native controls (median gt 11)
• morphosyntax pronunciation
• most learner samples not composed of pre-screened
  L2 high-proficients

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Nativelikeness in late L2A

• 2. Not restricted to a narrow or single domain
• Birdsong (2003) Marinova-Todd (2003) Multiple
  tasks covering segmental global pronunciation,
  vocabulary knowledge, morphosyntactic
  production/judgment, language use, etc.
• Marinova-Todd 3/30 subjects indistinguishable
  from native controls across 9 tasks.
• Birdsong 3/22 like natives on 5/7 tasks

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Nativelikeness in late L2A

• 3. Heuristic No limits on what is learnable
• There is no task involving L2 linguistic
  knowledge (or pronunciation accuracy) where
  nativelikeness is out of reach for all late L2
  learners at end state.

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Nativelikeness in late L2A

• 4. Heuristic Limits on what is processable
• L2 processing tasks where all late learners fall
  short of nativelikeness (e.g., Clahsen Felser,
  in press Dussias, 2004 Dupous Peperkamp,
  2002 Frenck-Mestre, 2005 Juffs, 2004
  Papadopoulu Clahsen, 2004)
• gt lexical retrieval
• gt structural ambiguity resolution
• gt detection of acoustic distinctions in syllable
  stress, vowel length, consonant voicing
• gt sentence processing - eyetracking
• Quantitative differences speed accuracy
• Qualitative differences shallow/deep
  processing local /non-local parsing mishearing
• ? Trainability

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Nativelikeness (L1-likeness) in late L2A

• 5. Neurofunctional similarities
• Abutalebi et al. (2005) Green (2005) Stowe
  Sabourin (in press) In terms of where (fMRI)
  and when (ERP), similarities with L1 in brain
  activation among L2 high-proficients, even late
  learners.
• to be continued

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Nativelikeness in late L2A

• 6. Incidence of nativelikeness derivable from
  slope of AoA function (Birdsong, 2005)

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Slope predicts incidence of nativelikeness
shallow slope
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Slope predicts incidence of nativelikeness
steeper slope
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Nativelikeness in late L2A

• 7. Incidence of nativelikeness affected by
  exogenous factors
• Bialystok Hakuta (1999) Flege et al. (1999)
  inter alia Slope of the age function (gt rate of
  nativelikeness) depends on L2 input / interaction
  / use / training education task etc.

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Nativelikeness in late L2A

• 8. Incidence of nativelikeness affected by
  linguistic factors
• Flege et al. (1999) Slope of age function (gt
  rate of nativelikeness) steeper for
• - knowledge of ungrammaticality than
  grammaticality
• - knowledge of lexical / morphosyntactic
  irregulars than regulars

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Flege et al. (1999)Korean L1 / English L2 (n
240) subset of Johnson Newport (1989) items
grammaticality judgment accuracy
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Nativelikeness in late L2A

• 8. (cont) Incidence of nativelikeness affected
  by linguistic factors
• Geometry of age function varies by L1-L2 pairing

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Johnson Newport (1989) (broken lines
squares)vs. Birdsong Molis (2001) (solid lines
circles)JN Chinese/Korean L1 BM Spanish
L1English L2 grammaticality judgment accuracy
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Non-Nativelikeness

• Bilingualism effects ? learning deficits

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Bilingualism effects

• L1 -gt L2
• L2 -gt L1
• Grosjean (1989) A bilingual ? 2 monolinguals in
  1 person
• Flege (2002) No perfect bilinguals

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Bilingualism effects

• L2 effects in the L1
• Pronunciation VOT (Flege Hillenbrand,1984)
• Lexis Collocations (Laufer, 2003)
• Syntax Middle voice (Balcom, 2003)
• Syntactic processing (Cook et al., 2003)
• Lexical decision (Van Hell Dijkstra, 2002)
• gt Grammaticality judgments Ungrammatical L1
  sentences that are grammatical in the L2 are
  judged more acceptable than sentences that are
  ungrammatical in both languages. (Altenberg
  1991 Pelc 2001)

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Bilingualism effects

• L2 effects in the L1
• The L1 of a bilingual is not the language of a
  monolingual, but differences lt? shortcomings in
  language learning ability. L2 effects in L1 are
  routine and normal in bilingualism (early
  late).

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Bilingualism effects

• L1 effects in the L2
• The L2 of a bilingual is not the language of a
  monolingual, but differences lt? shortcomings in
  language learning ability. L1 effects in L2 are
  routine and normal in bilingualism (early
  late).

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Bilingualism effects

• L1 effects in the L2
• GENERAL L1 effect Cognitive repercussions as a
  function of entrenchment maintenance of L1 Ex.
  Slower processing (segmentation, parsing)
  grammatical convergence lexical
  interpenetration
• GENERAL L1 effect High L1 use gt lower L2
  proficiency than high L2 users

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Bilingualism effects

• L1 effects in the L2
• SPECIFIC L1 effect Slope of age function (gt
  rate of nativelikeness) varies by L1-L2 pairing
  signatures of non-nativelikeness (types of
  accent) vary by L1
• Ex. Spanish L1 / English L2 shorter VOT lags
  than monolingual English English L1 / Spanish L2
  longer VOT than monolingual Spanish (Flege
  Eefting, 1988)

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Bilingualism effects

• Conceptual/theoretical implications
• All non-nativelikeness lt? learning failure
• (Some non-nativelikeness lt nature of
  bilingualism)
• ? Utility of nativelikeness (resemblance to
  monolingual) as a criterion for falsification of
  CPH/L2A
• X Utility of non-nativelikeness in support of
  CPH/L2A

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L2 Dominance nativelikeness

• ? Upper limits of late attainment seen in
  L2-dominants
• Flege, MacKay Piske (2002). Italian L1/English
  L2 bilinguals (1) L1-dominants, (2) balanced
  bilinguals, (3) L2 dominants. Detectable accents
  among 1 2 3 like native controls

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L2 Dominance nativelikeness

• Upper limits of late attainment seen in
  L2-dominants ASYMMETRY
• Golato (2002) English L1, late L2 French
  English dominants parse French words like French
  natives and English words like English natives.
  French dominants (L2 dominants) parse both
  English and French words like French monolinguals
  (open-syllable segmentation routine)

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L2 Dominance nativelikeness

• Conceptual/theoretical implications
• Age effects and L1 effects are confounded. If we
  could minimize L1 effects (i.e., study L1
  attriters or L2-dominants), what would the
  residual age effects be?

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L2 Dominance nativelikeness

• Conceptual/theoretical implications
• ? Dominance a predictor of attainment (a better
  predictor than AoA)
• H Degree of dominance (continuous construct,
  psycholinguistically operationalized see Flege,
  Grosjean, Golato, etc.) predicts degree of
  monolingual-like experimental performance.

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L2 Dominance nativelikeness

• Conceptual/theoretical implications
• ? AoA function (timing slope of decline) for
  those whose L1 is not dominant
• H Reduced L1 dominance / reduced L1 use predicts
  later offset and shallower slope of decline.

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L2 Dominance nativelikeness

• Conceptual/theoretical implications
• ? Brain-based data for L2-dominants
• H More similarities with native monolinguals
  than observed for high L2-proficients.

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L1-likeness in late L2A

• Neurofunctional similarities
• Abutalebi et al. (2005) Green (2005) Stowe
  Sabourin (in press) In terms of where (fMRI)
  and when (ERP), similarities with L1 in brain
  activation among L2 high-proficients, even late
  learners.
• continuation

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Age/Proficiency/Task L1-likeness

• Imaging studies
• Production tasks word repetition Klein et al.,
  1994 cued word generation Chee et al., 1999
  sentence generation Kim et al., 1997 cognate-non
  cognate naming De Bleser et al., 2003
• gt L2 proficiency, not AoA, predicts similarity in
  areas of activation between late L2 and L1
• gt Degree of similarity varies among studies
• gt Exposure differences and degree of proficiency
  differences

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Age/Proficiency/Task L1-likeness/early
bilingual-likeness

• Imaging studies
• Comprehension tasks Perani et al. (1996) PET
  Dehaene et al. (1997)
• gt Differential activation between L1 and L2
  low-proficients
• Comprehension tasks Perani et al. (1998) PET
  
• gt Overlapping patterns for high-proficiency late
  and early bilinguals

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Age/Proficiency/Task L1-likeness

• Imaging studies
• Comprehension judgment tasks Chee et al. 2001
  fMRI
• gt Late high proficients had relatively reduced
  brain activity in left prefrontal parietal
  areas
• Comprehension judgment tasks Wartenburger et
  al. 2003 fMRI DESIGN It/Ger early biling/hi
  prof late biling/hi prof late biling/low prof
• gt Activation for grammar judgments related to
  AoA, among high proficients (though groups may
  have actually differed in proficiency).
  Activation for semantic judgments similar for the
  high proficiency groups but more activation in
  bilateral BA 47 insula for late vs. early high
  proficients

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Age/Proficiency/Task L1-likeness

• Imaging studies
• Word-level meaning reference Chee et al.,
  (2000) Ding et al., (2003), Xue et al., (2004)
• gt Similar activation in L1 and L2 even in
  relatively low proficient, latish learners (Xue
  et al., 2004) (fusiform gyrus, Brocas, left
  parietal)

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Age/Proficiency/Task L1-likeness

• Imaging studies
• Degree of activation More voxels in a given
  area or more signal change for same voxels in L2
  versus L1, both early and late bilinguals.
  Increased neural activity interpreted as more
  effortful processing in L2 (Stowe Sabourin, in
  press).

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Age/Proficiency/Task L1-likeness

• NB Methodology
• Potential confounds with chronological age.
  Speed, accuracy, effort (Park, 2000) and
  ambiguity resolution (Kemper Kemptes, 2000)
  affected by age. Activation varies by
  chronological age Older adults may activate
  less, more, or even different neural structures
  (Park Gutchess, 2005 219).

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Age/Proficiency/Task L1-likeness

• ERP studies
• General observation Timing components of
  high-proficient L2 use are similar to those of L1
  use, AoA gt 12, (e.g., Ojima et al., 2005
  Proverbio et al., 2002 Stowe Sabourin, in
  press.)
• ? ELAN for word category violations not observed
  for late L2A (Hahne, 2001 Hahne Friederici,
  2001 Weber-Fox Neville, 1996)
• ? P600 effects found in some studies (Hahne,
  2001 Sabourin, 2003) but not in others (Ojima et
  al., 2005)

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Age/Proficiency/Task L1-likeness

• ERP studies
• L2-L1 similarities appear early in the course of
  L2A.
• McLaughlin et al. (2004) P600 effects for
  syntactic violations after 4 months of L2
  learning.
• Osterhout et al. (2004) Word vs. pseudo-word
  N400 effect after 14 hours of instruction.

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Age/Proficiency/Task L1-likeness

• ERP / fMRI
• ? Non-native behavioral results nativelike
  brain-based results gt amount of L2 learning
  understated in behavioral measures
• ERP Osterhout colleagues P600 N400
• fMRI Indefrey et al. (2005)
• gt However, Ojima et al. (2005) Late learners
  (Japanese L1/English L2) detected S-V agreement
  errors in GJT but did not show P600 effect

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II. Interpreting Age-Related Effects
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The age function

• Negative correlation of AoA and attainment
  measures
• Over AoA span linear function (other models not
  much improvement)
• Correlations between -.45 and -.77 median -.64

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The age function

• Disaggregation analyses yield mixed results
• JN sig overall sig early, random late
• BM sig overall ceiling early, sig late

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The age function

• Disaggregation analyses yield mixed results
• DeKeyser (2000) sig overall ns early, ns late

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The age function

• Summary of meta-analysis (Birdsong, 2005)
• gt Pooled data age effects persist indefinitely
  (not bounded, no period)
• gt Late AoA Typically significant
  postmaturational declines
• gt Early AoA Inconsistent effects, some flat,
  some random, some declining

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Age function in L2A critical period function?

• Definitional logic if (maturationally-based)
  critical period, then
• gt Age effects should be finite (1) if confined
  to a period (2) maturation is a discrete
  process/phase within aging
• gt Age function should look different pre- vs.
  post-maturationally (discontinuity synchronized
  with end of maturation) gt

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Age function in L2A critical period function?

• Stretched 7 Stretched L

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Maturationally-Based Critical PeriodGeometric
and Temporal Features

• 1 peak sensitivity 2 beginning of offset
• 3 end of offset 4 baseline
  sensitivity
• gt 3 coincides with end of maturation
• gt Age effects do not persist past 3

1
2
STRETCHED Z (Johnson Newport, 1989) (Pinker,
1994)
4
3
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STRETCHED Z (Newport, 1991)
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JN89 Early vs. Late AoA
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Age function in L2A critical period function?

• Stretched L illusory
• Stretched 7 elbow as late as 27.5

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Age function in L2A critical period function?

• X Conceptual Age effects end at end of
  maturation (L geometry) age effects begin at
  end of maturation (7 geometry)
• X Typical linear function over span of AoA
• X Persistent age effects
• v Evidence of 7 geometry / window of
  opportunity age non-effect
• X But with 7 geometry the window of opportunity
  extends past end of maturation
• X Not much evidence of L geometry

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Age function in L2A critical period function?

• Minimal necessary feature of gradient
  Discontinuity at some point in the overall age
  function. (Stevens, Bialystok colleagues,
  Flege, inter alia)

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Discontinuity via disaggregation
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Single linear model vs. elbow modelRe-analysis
of results of Flege et al. (1995) (Jan-Pieter de
Ruiter)
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III. The aging brain and L2A
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The aging brain

• Neurocognitive organizational analytic levels,
  relevant to language use/learning
• Functional/processing lexical encoding/retrieval
  processing speed/depth concatenation/coordinatio
  n of grammatical units in real time, etc.
• Functional/learning Hebbian learning
  explicit/explicit learning declarative/procedural
  memory etc.
• Brain structure hippocampus, striatum, etc.
• Cellular neurotransmission, regional volumes,
  etc.

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Cognitive aging

• Mechanisms of cognitive aging (Park, 2000
  Rogers, 2000)
• gt Decreases in processing speed
• gt Deficits in working memory
• (Decreases in suppression, i.e, focus on relevant
  material--possibly tied to working memory)

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Cognitive performance, by decade (Park, 2000)
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Cognitive aging

• General patterns (Bäckman, Craik, Park,
  Salthouse, inter alia)
• gt Tasks involving working memory or episodic
  memory performance declines start in young
  adulthood
• gt Associative memory incremental learning
  declines start in young adulthood
• gt Tasks involving priming, recent memory,
  procedural memory, semantic memory age effects,
  if observed, are mild
• gt Implicit memory in tasks involving lexical
  recall milder effects than for explicit memory
• All related to L2 use / L2 learning

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Cognitive aging

• General patterns, cont
• gt Fluid intelligence involving speeded solutions
  to novel problems (e.g. Digit Symbol) Steady
  decline over adulthood
• gt Crystallized intelligence Declines begin in
  late adulthood performance increase between
  early and middle adulthood

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L2A and cognitive aging

• NB Language processing
• Vocabulary knowledge (in high proficient L2 and
  L1) is crystallized intelligence serving language
  comprehension gt low effort, little error less
  so in low proficient L2
• Assumption gt conclusion In the typical case
  (low-L2 proficient / L1 dominants) the proportion
  of fluid intelligence involved in L2 use is
  greater than in L1 use gt impact of age in L2 use
  is greater than in L1 use

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L2A and cognitive aging

• NB Vocabulary knowledge vs. retrieval of
  phonological form in real time

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L2A and cognitive aging

• NB Where speed efficiency demands are made
• (A) declines begin in early adulthood
• (B) declines are typically linear and all are
  continuous Bäckman Farde 2005
• (?) Patterns consistent with L2 processing
  declines
• The early onset and gradual nature of the
  age-related cognitive decline could inform
  attempts to determine its biological origins.
  Specifically, whatever the proposed origin may
  be, it would strengthen the case if the causative
  factor(s) would show a similar onset and
  trajectory as the behavioral data (68)

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Age and brain volume

• General patterns (Raz, 2005) in vivo MRI
• gt Brain volume decreases with age, with degree
  and timing of declines varying by structure
• gt Typically linear, always continuous no
  leveling off

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Age, brain volume L2A

• General patterns, cont
• gt Gray matter volume linear decline beginning in
  childhood
• gt White matter volume linear increase up to
  early 20s plateau into 60s linear decline
  into old age
• gt Degree of decline (slope) varies with
  cardio-vascular health other biographical /
  lifestyle factors

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Age Effect Size by Region of Interest
(ROI)cross-sectional studies 20-80 yoa
magnitude of effect as age-volume rmean, median
interquartile range of r (Raz, 2005)
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Age Effect Size by ROI (Raz, 2005)

• Magnitude of effects (approx. coefficients)
  cross-sectional observation
• Prefrontal cortex r -.54
• Putamen r -.46
• Caudate r -.42
• Hippocampus r -.36
• Temporal cortex r -.32

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Age Effect Size by Region of Interest
(ROI)longitudinal studies volume decline per
year(Raz, 2005)
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Age Effect Size by ROI(Raz, 2005)

• Median annual declines (approx.)
• Entorhinal cortex 1.4
• Hippocampus 1.2
• Caudate nucleus 1.1
• Frontal lobe 1

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Striatum volume decline per year(Raz et al.,
2003)

• Median annual decline (approx.)
• Healthy adults (n 53) 20-77 yoa
• Caudate nucleus .83
• Putamen .73
• Globus palidus .51
• Shrinkage
• gt begins in young adulthood
• gt linear declines (same rate of decline for
  younger and older subjects)
• gt parallels dopamine declines in these areas

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Age, brain volume L2A

• NB Correlative w/ L2 behavioral data,
  volumetric declines not bounded
• Also Timing geometry by ROI
• Caudate, cerebellum cortical structures linear
  decline starting in adolescence, throughout
  lifespan
• Entorhinal cortex hippocampus greatest annual
  shrinkage, but not linear decline controversy
  w/r/t timing of onset (probably midlife)

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Age, brain volume L2A

• NB Timing cognitive aging
• In neocortical areas, timing of volume declines
  // timetable of associated cognitive task
  declines however, not well synchronized with MT
  declines - episodic/associative memory declines
  (Reuter-Lorenz, 2000)
• gt Neural resources (for which volume is a proxy)
  in some brain regions are better predictors of
  performance than in others

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Dopamine systems language

• Generalities
• Nigrostriatal dopamine (DA) role in efficient
  motoric function
• D1 D2 receptors diffusely distributed
  throughout the neocortex, esp. dense in caudate
  putamen areas of striatum.
• Bäckman Farde (2005) DA role in higher-order
  cognitive functions, some of which are implicated
  in language learning processing switching
  between attentional targets, motoric sequencing
  (verbal fluency), working memory modulation.
  NB Role of each in bilingualism

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Dopamine systems language

• DA in basal ganglia functions
• BG in syntax, lexicon phonology production
  (Crosson et al., 2003) and processing (Friederici
  Kotz, in press Moro et al., 2001 Newman et
  al., 2001), processing of rules vs. words
  (Teichmann et al., in press)

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Dopamine systems L2A

• DA in basal ganglia functions
• BG in L2A motivation reinforcement (Schumann
  1997, 2001, 2004) contribution to
  proceduralization (Lee, 2004), defossilization of
  automatized procedures (Lee, 2004) gt minimizing
  L1 influence / intrusion

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Age dopamine systems

• DA decrements with age when where
• Li et al., (2001) D2 receptor declines begin in
  early 20s and continue over lifespan. D2
  declines in BG hippocampus, amygdala, FC, ACC.
  
• Kaasinen et al., (2000) Extrastriatal D2
  binding losses TC, PC, OC, hippocampus, thalamus

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Age dopamine systems

• DA decrements performance
• Volkow et al. (1998) PET study (adults 24-86
  yoa) of striatal D2 binding potential behavioral
  measures on motoric, perceptual executive
  speed D2 receptor decline with age in caudate (r
  -.62) putamen (r -.7) similar correlations
  for performance measures
• Prull et al., (1999) Declining nigrostriatal DA
  system gt impoverished input to frontal lobes gt
  reduced executive capacity of working memory
  also attention inhibitory processes (Braver et
  al, 2001)
• Bäckman Farde (2005) With DA loss neural noise
  increases gt less distinctive neural
  representations gt declines in working memory
  executive function

84
Age, dopamine systems L2A

• DA role in a variety of cognitive functions
  underlying L2 processing and learning.
  Age-related DA declines candidate mechanism
  underlying age effects in L2 learning
  processing
• Age and other biochemical culprits (later life)
• gt Age-related declines in other
  neuromodulators/receptors, esp. ACh
• gt Age/Stress gt increases in cortisol levels gt
  hippocampal atrophy (Lupien et al., 1997, 2001)
• gt Aging and estrogen / testosterone mediating
  role in verbal production, memory, processing
  (Resnick Maki, 2001 Kimura, 1995)

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IV. The Nature of Age Effects
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Causal mechanisms mediating factors

• MacWhinney (in press) 10 concrete proposals
  relating AoA to ultimate attainment in L2
• Singleton (in press) 14 versions of CPH/L2A
• Birdsong (1999) 6 major variants of CPH/L2A,
  plus experiential endogenous factors in
  attainment

87
Causal mechanisms mediating factors

• Classes of explanation
• Neurobiological
• Neurocognitive
• Cognitive-developmental
• Affective
• Experiential

88
Causal mechanisms mediating factors

• Most factors/mechanisms are consistent with
  research
• All could be at work in some fashion in L2A, some
  accounting for more variance than others in the
  aggregate
• also individual differences
• Multidimensional, multifactorial, idiosyncratic
  nature of age effects

89
Summary

• Behavioral evidence
• 1. Unbounded L2 attainment declines ? period
• 2. Bounded age non-effects up to AoA 27.5
• 3. Timing of declines lt? maturational effects
• 4. Slope of function lt external factors
• 5. Non-(monolingual)nativelikeness lt
  bilingualism effects
• 6. Decline in cognitive processes underlying L2A
  use synchronized with behavioral declines
• 7. Despite 1,2,5,6 non-trivial incidence of
  nativelikeness among late L2 learners

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Summary

• Brain-based evidence
• 8. L1-like where when of brain activation
  usually better predicted by L2 proficiency than
  by AoA
• 9. Linear, unbounded volumetric declines in ROI
  comparable to gradients for L2 use/learning
• 10. Volume declines synchronized with cognitive
  function declines for some but not all ROI
• 11. Dopamine system declines synchronized with
  decrements in cognitive function underlying L2
  use/learning

91
Summary

• Further study
• 12. Non-nativelike processing vs. nativelike
  attainment in late L2A
• 13. L2 attainment processing among L2-dominants
  gt subtraction of general specific L1 effects
• 14. Linkage of cognitive aging to neural aging
  linkage of both to L2 declines over age
• 15. Factors/mechanisms of age-related declines

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• THANK YOU

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Causal mechanisms mediating factors

• Some factors/mechanisms not consistent with
  research
• Maturational accounts
• Implicit knowledge not acquirable past puberty
  
• Less is More (mixed support)
• Biological accounts predicting zero
  nativelikeness

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Dekeyser figure
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Specific L1 effectsEx. Van Boxtel (2005)

• L1 French LATE
• L1 German LEARNERS OF
• L1 Turkish DUTCH L2
• Sentence preference tasks and imitation tasks
  dummy subjects in Dutch
• - L1 French L1 German scores more often in
  native range than L1 Turkish scores
• - more French German L1ers at near-nativelike
  levels

100
Age function in L2A critical period function?

• Finite effects elbow at puberty gt

101
Young vs OldImplicit vs Explicit Memory(Park,
2000)