Quemart, P. & Maillart, C. (2016). The sensitivity of children with
SLI to phonotactic probabilities during lexical access. Journal of Communication Disorders, 61, 48-59.
This study examined how children
with specific language impairment (SLI) use certain language cues to help with vocabulary
learning. Children with SLI have typical intelligence, hearing, and motor
skills, but struggle with learning language at the same rate as their peers.
Examining different factors that lead to successful vocabulary acquisition may
contribute to our understanding of the language difficulties seen in children
with SLI. Sensitivity to phonotactic
constraints may be one factor that helps language learners with vocabulary
acquisition. Phonotactic constraints are how sounds can be ordered within words
within a particular language. For instance, English words can end with /fs/
(e.g., ‘laughs’), but cannot begin with /fs/. Phontactic constraints vary
within a language, with some constraints occurring across more words, or being more
frequent, than others. These constraints are easily acquired: By about nine
months of age, infants are able to differentiate between legal and non-legal
phonotactic constraints in their native language. Once acquired, knowledge of phonotactic
constraints is involved in word learning, spoken word recognition, and the
selection of appropriate verb inflections. The authors wanted to examine
whether children with SLI were sensitive to phonotactic constraints, and
whether this sensitivity differed from that of typically developing children.
Children with SLI and
typically developing children heard a list of words and non-words, one at a
time, and had to correctly identify the real words and correctly reject the
nonwords. Importantly, the nonwords were made up of phonotactic constraints
that were highly frequent in their native language (French), or phonotactic
constraints that were not frequent. That is, some of the nonwords were made up
of sound combinations that occur in many French words, while others were made
up of sound combinations that occur in few French words. If the children were
sensitive to patterns involving phonotactic constraints, it should be easier to
quickly reject the nonwords containing non-frequent sound combinations, and
harder to reject the nonwords containing highly frequent sound combinations. The
authors found that compared to typically developing children, children with SLI
were worse at correctly rejecting nonwords that contained highly frequent
phonotactic constraints. That is, the children with SLI had more difficulty
rejecting nonwords that sounded similar to other words in their vocabulary. Typically
developing children, on the other hand, could quickly and accurately reject all
of the nonwords, perhaps because they had a better-developed vocabulary.
It seems that children with
SLI are at least sensitive to the phonotactic constraints within their native
language. But, they may be over-reliant on this cue compared to children with
typical language skills, who can instead rely on their stronger vocabulary knowledge.
These results underscore the importance of vocabulary knowledge in supporting
language processing, and the need to support vocabulary learning in children
with SLI perhaps on an extended basis.
Blogger: Nicolette Noonan is a Ph.D. student with Drs. Lisa Archibald
and Marc Joanisse