How far and how fast? A longitudinal study of ASL acquisition in adolescent
homesigners
Language acquisition in deaf children rarely begins at birth. Nevertheless, we know relatively little
about the developmental milestones in sign language acquisition following delayed exposure, and
the trajectory of sign language acquisition following the use of homesign is virtually unexplored.
Previous studies have either considered a single time point in development1,2, or have focused on
the acquisition of classifier constructions3. The present study is the first longitudinal analysis of
ASL vocabulary and sentence development in three deaf teens who had been cut-off from nearly
all language until adolescence; they did not have meaningful access to speech and, due to various
circumstances in their upbringing, have not been exposed to any kind of sign language. They used
limited gestures and pantomimes to communicate prior to the onset of ASL acquisition at age 14
years.
Our participants, named Shawna, Cody, and Carlos, have been exposed to ASL from 12 to 24
months at the time of first testing (Time1)4. In the present study, we focus on growth in vocabulary
and syntax between Time1 (12-24 months of total language exposure) and Time2 (30-42 months
of total language exposure). The size and composition of the participants’ lexicons were assessed
with the MacArthur-Bates Communicative Developmental Inventory (CDI) for ASL5, and by
analyzing their spontaneous ASL production. We analyzed growth over time with respect to typetoken ratios, utterance length and complexity. A more detailed analysis of the use of verb types is
currently underway.
Our findings suggest that while Shawna, Cody, and Carlos initially acquire signs faster than child
L1 learners (Time1), after this initial growth ASL acquisition tapers off and is not characterized by
the explosive and linear growth patterns characteristic of child L1 learners6,7. Thus while overall
vocabulary and type-token ratio increased from Time1 to Time2, (Fig 1) they continue to use few
closed class signs at Time2, and their utterances remain simple. Their mean length of utterance
(MLU), which was comparable to that of young children acquiring sign from birth at Time14,
remains small and is below that of typically developing children8 at Time2 (Fig 2). This suggests
that adolescent L1 learners can acquire new, simple lexical items, but may be unable to acquire a
more diverse and complex vocabulary and syntax that would allow them to produce longer, more
complex utterances. These findings contrast with those from studies of the early English
acquisition of Chinese 2;7 to 5;1 year old children adopted by American families9, which suggest
rapid vocabulary and MLU growth.
Our findings suggest that the acquisition of initial vocabulary and simple utterances is common to
all L1 learning, and can occur even when exposure to language is severely delayed. We propose
that a larger, more diverse lexicon and longer, more complex utterances develop from a previously
acquired simple lexicon and shorter utterances, but only when acquisition begins at a young age.
The slowing of lexical and syntactic acquisition that we observe here suggests that the later stages
of language acquisition are age-sensitive, and we discuss why this may be so.
500 words
References:
1.
Berk, Lillo-Martin (2012) Two word stage: Motivated by linguistic or cognitive constraints?
Cognitive psychology, 65(1) 118-140
2.
Emmorey, Grant, Ewan (1994). A new case of linguistic isolation: Preliminary report. Paper
presented at the 19th annual Boston University Conference on Language Development
3.
Morford (2003). Grammatical development in adolescent first-language learners. Linguistics 41,
681-721.
4.
Ferjan Ramirez, Lieberman, Mayberry (Available on CJO 2012doi:10.1017/S0305000911000535)
The Initial Stages of First-Language Acquisition Begun in Adolescence: When Late Looks Early.
Journal of Child Language.
5.
Anderson, Reilly (2002) The MacArthur Communicative Development Inventory: Normative
Data for American Sign Language. Journal of Deaf Studies and Deaf Education, 7, 83-106
6.
Bates, Dale, Thal (1995) Individual differences and their implications for theories of language
development. In Fletcher and MacWhinney, eds., The Handbook of child language. 96-151.
Oxford:Blackwell.
7.
Bates, Goodman (1997) On the inseparability of grammar and the lexicon: Evidence from
acquisition, aphasia and real-time processing. Language and Cognitive Processes, 12, 507-584.
8.
Rice, Smolik, Perpich, Thompson, Rytting, Blossom (2010) Mean length of utterance levels in 6month intervals for children 3 to 9 years with and without language impairments. Journal of Speech,
Language, and Hearing Research, 53, 333-349.
9.
Snedeker, Geren, Shafto (2007) Starting Over: International Adoption as a Natural Experiment in
Language Development. Psychological Science, 18: 79-87.
Type-­‐token Ratio 0.7 0.6 12mo 30mo 18mo 36mo 24mo 42mo 0.5 0.4 Time 1 0.3 Time 2 0.2 0.1 0 Shawna Cody Carlos Figure1: Type-token ratios for the cases at Time1 (blue) and Time 2 (red)
Cases at Time 2
Typically Developing
Children8
2.7 (Shawna, 30 mo exposure) 2.9 (30 mo old)
2.9 (Cody, 36 mo exposure)
3.4 (36 mo old)
2.6 (Carlos, 42 mo exposure)
3.7 (42 mo old)
Figure 2: Mean Length of utterance (words) for the cases at Time2 and typically developing
children with the same length of language exposure.