Clinical Trial Details
— Status: Recruiting
Administrative data
| NCT number |
NCT04558541 |
| Other study ID # |
20-78 |
| Secondary ID |
|
| Status |
Recruiting |
| Phase |
N/A
|
| First received |
|
| Last updated |
|
| Start date |
August 7, 2022 |
| Est. completion date |
July 31, 2026 |
Study information
| Verified date |
June 2023 |
| Source |
The University of Texas at Dallas |
| Contact |
Lisa Goffman, PhD |
| Phone |
972-883-3043 |
| Email |
Lisa.Goffman[@]utdallas.edu |
| Is FDA regulated |
No |
| Health authority |
|
| Study type |
Interventional
|
Clinical Trial Summary
The broad aim of this clinical study is to assess the hypothesis that morphological and
phonological deficits are linked by a broader deficit in sequential pattern learning. This
hypothesis applies to learning in general, but is especially critical as an avenue for
developing earlier assessments and more powerful interventions for children with
developmental language disorder (DLD; also known as specific language impairment). Other
populations, such as at-risk toddlers, may also benefit from this new approach.
Description:
The developmental approach taken here combines what is already known about morpho-syntactic
deficits in DLD with recent developments in the fields of linguistics and language
acquisition. First, it is possible to divide phonological and morphological patterns into
three pattern types (Single Feature, OR/Disjunction, Family Resemblance/Prototype), with
these types having a long history of study in visual pattern learning. Importantly, children
with DLD appear to have maximum difficulty with morpho-syntactic patterns of the OR type
(e.g., regular past tense; add a "t" if the final consonant is voiceless OR a "d" if the
final consonant is voiced). In contrast, studies using artificial grammars show that infants
who are typically developing are highly adept at learning Single Feature and OR pattern
types; Family Resemblance patterns may be weaker. Family resemblance patterns relate to
similarity, and may be more closely tied to the lexicon than to grammar (e.g., beagles and
terriers are similar and they are both dogs; the words "goat" and "boat" are similar).
Typical adults are adept at Single Feature and Family Resemblance patterns, but appear to be,
at least superficially, more like children with DLD in their performance on the OR pattern.
With these developmental findings as a starting point, the proposed research links
phonological and morphological sequence learning in children with developmental language
disorder (DLD). In the studies focused on children, the investigators ask if 4- to
6-year-olds who are typically developing as well as those with DLD (both with and without
co-occurring speech sound deficits) and speech sound disorder (SSD; without co-occurring
morpho-syntactic deficits) are sensitive to input examples that fit one of these three
patterns. The hypothesis is that, consistent with their long-documented morpho-syntactic
deficit, children with DLD will have particular difficulty with the OR pattern. Consistent
with their intact morpho-syntactic skills, children with SSD should show no deficits in the
OR pattern, revealing a link between OR pattern learning, phonology, and morpho-syntax. The
endpoint measure is that children with DLD (both with and without an accompanying SSD) do not
show sensitivity to the OR pattern, as measured by sound pattern (e.g., phonetic accuracy,
syllable sequence stability) and motor learning (e.g., articulatory and acoustic variability)
measures.
This hypothesis is assessed by indexing the learning trajectory across the training period
and during generalization to new nonwords that are consistent or inconsistent with the
training pattern. In the generalization phase, children are asked to name new novel words
that are either consistent (i.e., that fit the training rule) or inconsistent (i.e., that do
not fit the training rule) nonwords. It is predicted that children with TD and SSD, who are
still in a period of language learning plasticity (they can still learn the sound patterns
and grammar of a second language) will be sensitive to all three patterns. However, children
with DLD (both with and without accompanying SSD) are predicted to show sensitivity to the
family resemblance and single feature patterns, but not to the critical OR pattern-the one
associated with sound pattern and grammatical learning, This would reveal an important
connection between sound pattern and grammatical learning, which could lead to earlier
diagnosis (phonological patterns emerge earlier than grammar) and to more general
intervention practices that focus on sequential pattern learning rather than specific
language goals may be efficacious.
A second aim explores whether the inclusion of a semantic subcategory cue facilitates
learning the OR pattern. The hypothesis is that children with DLD (as well as typical adults)
who initially are predicted to have the most difficulty with the OR pattern, will show
increases in sensitivity following the addition of a semantic category cue (e.g., animals for
the voiced consonant rule OR tools for the voiceless consonant rule). This result would be
especially important for learners with DLD, as it may provide a pathway for intervention of a
core learning deficit.
Critically, these studies are developmental in nature. In the adult component of this
research (conducted under a separate clinical trial, Gerken, University of Arizona), the
investigators ask if adults are sensitive to input examples that fit one of these three
patterns. The hypothesis, based on previous findings from the Gerken lab, is that adults,
like children with DLD, do not show sensitivity to the OR pattern. However, adults are
sensitive to single feature and Family Resemblance patterns. Adults still learn words readily
and are sensitive to family resemblance prototype relationships. For adults, perceptual
measures index sensitivity. Similar to the children with typical development, DLD and SSD,
the investigators explore whether the inclusion of a semantic subcategory cue facilitates
learning the OR pattern in adults. The hypothesis is that all learners, including adults,
will show increases in sensitivity following the addition of a semantic category cue (e.g.,
animals for voiced rule OR tools for voiceless rule). The findings from adults contribute to
a dynamic developmental framework. Because of the dramatic developmental changes in
sensitivity to phonological sound patterns and the presumed linkage of such patterns to
morpho-syntax, the data from adults are essential in identifying the underlying mechanism(s)
of DLD and to suggesting possible intervention strategies, such as employing semantic cues to
the OR pattern and strengthening lexical organization.
From previous work, it is known that infants are sensitive to the OR rule. In the studies
focused on toddlers (also in a separate clinical trial conducted by Gerken at the University
of Arizona), the investigators ask if dependence on the associatively organized lexicon can
account for the infant-to-adult developmental changes observed for the OR pattern (which is
not associatively organized) and thereby explores the possibility that children with DLD rely
on their lexicons to compensate for their sequential pattern learning deficit. The hypothesis
is that 20-month-old children, who are just entering a period of rapid vocabulary learning,
will show increased sensitivity (based on looking time to words that are consistent vs.
inconsistent within the training set) in the family resemblance condition when a visual
referent (i.e., semantic cue) is added, but decreased sensitivity in the OR condition when a
visual referent is added. These results will also be related to vocabulary size as reported
on the MacArthur-Bates Communicative Development Inventory, with the prediction that robust
patterns are smaller for children who received referents or who have smaller vocabularies for
the OR pattern and greater for children who received referents or who have larger
vocabularies for the family resemblance pattern. The results from toddlers, who are just
entering a period of rapid vocabulary learning, provide an essential framework for
understanding how different types of phonological patterns apply to lexical and
morpho-syntactic learning.
The results of the proposed studies provide a critical developmental framework for
identifying the underlying mechanism(s) of DLD. These findings will also lead to the
development of intervention strategies, such as strengthening lexical organization, to
support problematic aspects of sequential pattern learning.
