Title: Interpreting Age Effects in Second Language Acquisition
1Interpreting Age Effects in Second Language
Acquisition
David Birdsong
- A presentation of David Birdsongs chapter from
the Handbook of Bilingualism Psycholinguistic
Approaches edited by - Judith F. Kroll and Annette M.B. de Groot
David Counselman Final Project APLNG 591 SLA
December 11, 2006
2Introduction
- There is an undeniable, general correlation
between age and skill at picking up a foreign
language. - Many have contributed this to a critical period.
- This is reasonable, considering some other
evidence from science
3Cont
- For example, there is a timetable associated with
song learning in some birds (Marler 1991) - Also, for vision in cats to develop fully,
stimulation must be exposed to the visual cortex
within the first three months of age (Hubel and
Wiesel 1965) - However, some researchers arent convinced that
language acquisition is subject to a similar
critical period.
4Outline
- A general orientation to typical methodologies in
SLA age factor research - A view of temporal and geometric features
characteristic of critical periods - More specific data found within SLA research on
the age problem - The question of native-like performance and how
it relates to the slope of the age-function - Determining the slope of the age function
- Concluding remarks
5The Age Question in SLA Research
- Often, as well as in this chapter, the age
variable is the age of arrival (AoA) into the
culture of the L2 - The issue of the end state
- Researchers usually set a bottom cut-off point
for Length of Residence (LoR) like 10 years - Usually, the issue is the following
- How does AoA affect L2 attainment or competency?
6Cont
- Specifically, these are run experimentally in the
laboratory - subjects are asked to complete any of various
tasks used to rate language competence. - Results vary depending on setting, methodology,
etc. - Even presentation of material (orally vs
visually) can make a difference (Bialystok and
Miller 1999, Johnson 1992)
7Cont
- This brings up an important fact
- The function of the effect of age will vary
depending on the area of the L2 grammar being
considered (e.g. Bialystok and Miller 1999,
Birdsong and Flege 2001). - Linguistic feature, amount of L2 use, and L1-L2
pairing have all been found to play a role as
well (see Flege, Yeni-Komshian Liu 1999, Moyer
1999, Scovel 1988, Seliger 1978)
8- Research has also looked at neurological
dimensions of the issue, although these issues
are not considered in detail in this article. - Event-related brain potentials, fMRI, and
positron emission tomography, for example. - Also, do polyglots engage distinct neurological
substrates in processing/ representing each
language? - Some evidence converges to say that high levels
of L2 attainment correlate with the use of a
common neurofunctional organization for the L1
and L2 (see Brovetto 2002 for further discussion
of this issue).
9Geometric and Temporal features of Critical
Periods
- Generally, a critical period refers to a
temperal span during which an organism displays
a heightened sensitivity to certain environmental
stimuli, the presence of which is required to
trigger a developmental event.
10- Some people assume the degree of sensitivity is
constant throughout this temporal span (as
pointed out by Bornstein 1989 183), which would
imply
11This view will be taken here
- Bornstein (1989) also noted, however, that a
critical period, by definition, includes the time
during its onset and offset, and so the function
should look like this
12A CP for language acquisition
- Since sounds like ba and pa can be
distinguished by newborns a few hours old (Eimas,
Siqueland, Jusczyk Vigorito 1971), it can be
argued that the onset essentially begins at
birth. - Most accounts consider full adult-like competence
to be possible if language learning begins by 4
to 7 years of age. The beginning of the offset,
could, therefore, be roughly located around this
age.
13Cont
- It is argued (Johnson and Newport 1989) that
critical period effects for language acquisition
should end around the point of complete
neurocognitive maturation, roughly in the
mid-to-late teens. - This could be the end of the offset of the CP.
14This provides the following
15Other possible age-functions
- No end point the decline in attainment of
language continues throughout the lifespan.
All of these functions will be compared with the
CPH (Lenneberg 1967) and with observations found
in the SLA literature.
16CPH in the context of SLA
- The CPH has been formulated in various ways
- Increasing age entails
- Decreasing neural plasticity in the relevant
cortical areas (Lenneberg 1967, Pulvermüller
Shumann 1994) - Loss of access to the language learning faculty
or universal grammar (Eubank Gregg 1999) - A gain in information processing capacity that
might be ill-suited to the task of language
acquisition (Newport 1991) - Dismantling of relevant cortical circuitry
(Pinker 1994) - Loss of function of mediating mental faculties
from lack of use (Bever 1981) - The inhibition of learning by entrenched L1
knowledge (Marchman 1993) - See Birdsong (1999) for further discussion.
17The function described by a CP
- Pinkers proposal (1994 293-294) is the only one
that makes claims for the end of the offset,
thereby fitting the function for critical
periods, which has already been shown - Pinker proposes that once the faculty to learn
language has completed its task (once weve
reached puberty and have learned our L1), it gets
discarded to save metabolic energy. (liked to
floppy disk)
18- Johnson and Newport (1989) make a similar
proposal (which fits the geometric and temporal
features of a CP), but without mention of the
same set of neural and metabolic mechanisms as
Pinker. - Other proposals do not predict a leveling off at
the end of the critical period, and therefore
cannot define a CP function, but well see that
these proposals arent unworthy, they in fact
seem to be even closer to reality.
19Behavioral Data
- The primary argument against the CPH is that the
data regularly fail to show a leveling off that
signals the end of the CP. - If language learning is related to maturation,
there isnt any maturational difference in a 17
y/o and a 27 y/o, so the CPH claims that people
of both ages should reach the same level of
attainment (Johnson and Newport 1989 79)
20Straight-line Age Effects
- Flege (1999) reanalyzed data from Flege et al.
(1995) to show that there was no discontinuity in
ratings of perceived foreign accent as
a function of age.
21Cont
- Flege (1999) also reports that in Yeni-Komshian,
Flege Liu (1997), there was also no evidence of
a break in linearity. - Hakuta, Bialystok Wiley (2001) found the same
type of linear function when analysing the 1990
U.S. Census results, which included self reports
of Chinese and Spanish immigrants English oral
proficiency.
22Cont
- Bialystok and Hakuta (1999) looked at a subset of
these immigrants who had LoR of at least 10 years
and whose AoR ranged from 0 60 - Again, theres a linear trend in the data
- The results of these analyses
23Chinese Spanish
24Cont
- Flege et al. (1999) also found no evidence for a
discontinuity in accent ratings of 240 Korean
immigrants - but DID find a slight discontinuity in their
scores on a 144-item test on knowledge of English
morphosyntax. - However, even late-arriving Koreans were subject
to a negatively-sloping fuction of age.
25Disaggregation Analyses
- These analyses, in which age groups are divided
at some age near puberty or a little after, often
show a discontinuity in the slope of the age
function. - Patkowski (1990), for example, analysed his 1980
dissertation data by dividing his subjects into
early (younger than 15) and older (older than 15)
learner groups - Early arrivals regression line .052
- Late arrivals regression line .028
26Johnson Newport (1989)
- Used this method
- Results provided evidence in favor of the CPH
- Birdsong and Molis (2001) replotted the JN89
data and proved different results. - BM01 also replicated the JN89 study with
Spanish natives, and obtained a totally observe
pattern.
27- Here, the dotted line, JN89 shows a decline in
early stages and a leveling off near the end
(CPH) - But BM01s replication of the study shows
different results, in which there is a ceiling
effect for early learnings and then a continuous
decline after age 16.
- There is no patten here for the late arrivals.
- While this doesnt provide evidence for what the
function may look like, it definitely does not
provide evidence for a leveling off and bottoming
out of the function in late arrivals.
28Cont
- Also interesting, and important, is that
Bialystok Hakuta (1994) reanalyse the JN89
data - and find that by moving the age of arrival
split to 20 years of age - the linear correlation of late arrivals
increased to significance.
29Summary from the data
- Some studies show a steady continuous decline in
language attainment as a function of age. - Others show that there is a discontinuity, where
the slope for the late arrivals is much steeper
than for early arrivals. - In either case, there is NO evidence for a
flattening out of attainment, which rejects the
notion of an endpoint to the decline of
sensitivity at some age after puberty.
30The functions we looked at
- These results do not support the function
associated with the CPH. Results that suggest a
discontinuity look more like graph C, while other
studies resemble the graphs A or B, depending.
31Nativelike Attainment
- In the experimental context, usually defined as
falling within the range of native speakers - Some researchers strictly define that
nativelikeness must fall within one standard
deviation of native speakers. - Some argue (Long 1990) that if late learners
achieve nativelike scores on experimental tasks,
this provides evidence to refute the CPH.
32Cont
- In earlier research, evidence for this was not
found. - In latter research, however, much evidence of
this type has been found. - It is interesting though that most late learners
who fall within nativelike ranges are usually
earlier late learners (late teens).
33Cautions should be considered
- Both the native speaker and immigrant subjects
should be taken from the general population, and
not the cream of the crop - Some L2 speakers have had varying degrees of L2
exposure prior to immigration. - The L2 sample should be controlled to make sure
subjects are at or near the end-state. (2 years
VS 25 years)
34Other problems implications
- It can also be problematic to compare any
bilingual to a monolingual native-speaker group. - A bilingual is not two monolinguals in one
(Grosjean 1989) - Previous studies that have claimed 5 or less of
the population reaches native-like proficiency
(Bley-Vroman 1989, Selinker 1972) may not have
been sampling the right group of people.
35Nativelike Attainment and the Age Function
- It should be considered that the likelihood of
nativelike attainment in latter ages is subject
to the slope of the age function.
- Steep slope implies less chance of nativelike
attainment in older ages. - Shallower slope implies more chance.
36Age and Other Factors
- If the slope of the age function is so crucial to
determining the likelihood of attaining
nativelike competence - how can we determine the slope?
- what affects the slope the function?
- what exactly does the function look like?
37Cont
- Years of education have been found to play a role
(Bialystok and Hakuta 1999) - Greater use of the L2 has correlated with less
perceived foreign accent (Flege colleagues) - A variety of other cognitive, task-related,
attitudinal, experiential, demographic, aptitude,
and training variables may affect the slope as
well.
38Different aspects of linguistic knowledge
- It is also important to note that the age
function does not affect all areas of language
competence the same (Eubank and Gregg 1999, Flege
et al. (1999), Flynn and Manuel (1991), Seliger
(1978), and others). - For example, Birdsong and Flege (2001) found that
increasing AoA did not affect accuracy of
knowledge of regular verb forms in English, but
it did affect the knowledge of irregular verb
forms.
39(No Transcript)
40Declarative VS Procedural Memory
- Birdsong (2004) suggested that the effect of
aging on declarative memory is likely a big issue
here. - Declarative memory declines much more with age
than procedural memory does. - This distinction should also be considered, when
trying to understand the age function on language.
41Conclusion
- The observations observed in this chapter
illustrate evidence that the age function does
not match the predictions of the CPH - Degree of L2 attainment does not appear to be
linked to maturational milestones, but rather
with age in general. - The likelihood of native-like attainment
decreases throughout the age spectrum (not does
level off) progressively.
42Cont
- Not everyone experiences this decline to the same
degree or at the same pace. - Whatever it is that allows language acquisition
(brain plasticity?) is not one thing that affects
the global mechanism for language learning - age affects the acquisition of various
linguistic features differently (regular vs
irregular, for example).
43Closing remark
- Flege opened and closed his plenary speech (age
effects on L2A) at the Conference on Hispanic
Linguistics and Acquisition by saying - I hope you now understand less about the effect
that age has on language acquisition than you did
before the presentation.
44References
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