Effectiveness of Language in Interaction Therapy in preschool children with developmental language disorders

Specific Language Impairment (SLI) is diagnosed when a child*s language
development is deficient: children experience severe difficulties in speech
production and understanding of language. Grammar (complex language) is an area
of language that is particularly affected. Effective intervention is important
since language impairment severely hinders communication in everyday life and
limits learning and school success. Intervention studies in SLI are scarce and
there is a lack of evidence for current treatment approaches.

The research questions are:
1. What is the effectiveness of Language in Interaction Therapy on the use of
grammar in spoken language of children age 4 and 5 with Specific Language
Impairment in comparison to usual care?
2. What is the effectiveness of Language in Interaction Therapy on
comprehension of grammar?

The study is an intervention study with an experimental single subject time
series design and a non-equivalent control group. An ABA-design will be used:
children will receive usual care in the first phase (A). Then the
speech-language therapists (SLTs) will be coached in using Language in
Interaction Therapy (LIT) after which the children will receive the
intervention LIT for 12 weeks (B). Afterwards the children will receive usual
care again, with the expectation that SLTs will use LIT more often than before.
This usual care (A) phase is referred to as A+. The A+ phase will be followed
by a phase without intervention during the summer holidays (8 weeks).

Measurements will be carried out every 4 weeks, 10 times in total. An 11th
follow up measurement will be done 10 weeks after the last measurement (T11).
On T1-T5 the development of the participants will be measured in the usual care
condition. Subsequently the intervention group will receive LIT, resulting in
a change in the way the language therapy is given, whereas other factors in the
special education setting will stay the same (measurement T6 t/m T8).
Measurements T9 en T10 will take place after finishing the LIT treatment, to be
able to register improvement and lasting effects of CTT in the new usual care
phase (A+) and in a phase without treatment.

Data of each individual participant will be analyzed separately as follows:
1. Visual analysis of the graphs with scores plotted against time. Because, at
least some, improvement is expected in all phases, trends will be analyzed and
compared. In case LIT is effective, the graphs will show a steeper rising line
in the LIT phase than in the usual care phase.
2. Calculating the effect size by:
- determining the Standard Mean Difference between the first usual care phase
(A) and the LIT phase (B) for each participant. The same will be done for the
LIT phase and the post treatment phases (usual care influenced by LIT (A+) and
the control phase during the summer holidays).
- calculating the Percentage Non-Overlapping Data (PND): the proportion of
the total number of intervention points that exceeds the highest baseline point

The control group will receive usual care during the total research period and
measurements will be carried out at the same moments. Although a control group
is not common in a single subject design, in this study it is necessary to
demonstrate that the improvements of the children are not influences by
unforeseen school matters, such as a change in education policy or a sudden
intake of many new pupils.

The SLTs on every participating school will be randomly selected to give LIT or
to continue usual care for the whole period. Every school will have an equal
amount of SLTs in each group. The study will take place on schools for special
education for children with speech, language and communication needs and will
last a little more than one school year (15-08-2016 to 01-10-2017).

Language in Interaction Therapy (LIT) and Usual Care, both administered by
speech and language therapists.

Intervention LIT:
During this intervention the SLT is playing with the child with toys, real
objects or craft supplies, frequently using the grammatical structures, the
child has to learn. In advance, the SLT decides which grammatical structure
will be the goal of the therapy session and she chooses toys and play
activities that will create opportunities for using the grammatical structure.
While playing, the SLT follows the child*s lead in play and communication and
responds to the child*s utterances. Using verbal techniques that have been
identified to improve the child*s perception of the correct language model
(emphasizing, reducing speech rate, eye contact, expressive intonation and
facial expression, using contrastive sentences), the SLT stimulates the child
to use the targeted grammatical structures. Grammatical rules are not explained
explicitly.
The frequency of the intervention is once a week for 20 minutes. In the LIT
phase of the study, the intervention will replace a regular therapy session, so
the determined therapy dosage will remain unchanged.

Control condition usual care:
In the usual care phase the SLTs will administer language therapy in a regular
way, designed in accordance with their own judgments. The control group will
receive usual care for the total duration of the study.
Therapy goals of usual care are comparable to the goals of LIT, but there is a
large variety in methods and therapy aids used. Usually both playing together
and exercises are practiced. During play in usual care, elements of LIT are
used, as well as broad targeted language stimulation. In exercises on the other
hand, the focus of attention is often one specific sentence, for example in
functional imitation with toys and work sheets. In functional imitation, a
child has to imitate the SLT, while they are both performing the same action in
rotation. Another exercise is the visualization of sentences to stimulate the
insight in grammatical rules.
Usual care will be administered in the dosage, determined by the school,
usually twice a week for 20 minutes, individually or in a small group (3-4
children).

The burden for the children is minimal and there are no risks.
There are no adverse effects of speech and language therapy. For the
participating children, Language in Interaction Therapy is in many aspects
comparable to the therapy they usually receive. The intervention will be
administered by the child*s own speech and language therapist, once a week. It
will replace a regular therapy session, so the determined therapy dosage will
remain unchanged and children will not be taken out of the classroom for extra
therapy sessions.
*
Measurements consist of a play session with the research assistant and two
short language tests. The tests are hardly a burden and contain the attractive
element of coloring on an iPad. Children are pulled out of the classroom for
only half an hour for each series of measurements.