Training Verbal Mediation to Support Executive Function in Children With Developmental Language Disorder

This project aims to determine the impact of modeling verbal mediation on the executive function (EF) of shifting in school-aged children with DLD. The investigators will determine the effect of modeling verbal mediation on the use of verbal mediation (Aim 1) and behavioral and electrophysiological measures of shifting (Aim 2). Because accuracy and reaction time are not direct measures of the cognitive process that leads to shifting, they will be supplemented with an electrophysiological marker of shifting that reflects real-time cue processing.

PARTICIPANTS: Seventy-five children (N = 75) aged 8 to 10 years will be enrolled in this study over the course of three years. Target enrollment is 25 children in each group (DLD-training, DLD-control, TD-control) matched on age (+/- 3 months) and gender. Over-recruitment of 85 total participants accounts for up to 14 percent attrition due to excessive artifacts in the EEG recording such as excessive eye blinks and/or movements (estimated at 10 percent), or a participants failure to complete all study tasks and tests (estimated at 4 percent). It is important to note that the project is based on a system for EEG recording that is optimized for use with children, and that the PI has used this system to study children in this age range with minimal loss of data due to artifacts. See the EEG data acquisition and processing sections for details.

Age Justification: This age group was selected because (1) children have made substantial development in spoken language and EF by this time, (2) the early school years are considered a key period in development as children are faced with external challenges that require them to use language and executive skills efficiently, and (3) evidence exists that this age range marks a period with extensive use of verbal mediation to support EF task performance.

GENERAL STUDY PROCEDURE: The study will involve (a) standardized assessments of language and cognitive skills described below and (b) an experimental protocol including three phases: pre-intervention, intervention, and post-intervention. Each phase will require 1 visit to the research lab, with 1-2 weeks between each phase, and a desired timeframe between pre- and post-intervention sessions of 14-21 days.

• Classification to DLD and TD Groups: Children with DLD will have a history of delayed language development as reported by a caregiver during an initial phone screening and will meet the criteria for DLD as determined by administration of standardized assessments of language and cognitive skills. Children will be confirmed as having DLD if they obtain an Identification Core Score (ICS) of less than 34 on the Test of Integrated Language and Literacy Skills (TILLS). Children with TD will not have a history of delayed language development and they will obtain a score of 34 or higher on the TILLS. All children must obtain a standard score greater than 70 on the Fluid Subtest of the Kaufman Brief Intelligence Test, 2nd edition (KBIT-2) to exclude those with cognitive impairments.
• Assignment to Training or Control Conditions: The study is an individually randomized trial with a parallel intervention design. All TD participants will complete the control condition. DLD participants will be randomly assigned to either the training or control condition. Randomization will occur after confirming classification to the DLD group and before beginning the intervention phase of the experimental protocol. The PI will oversee a block randomization protocol to assign participant IDs to either the training or control condition. Distinct teams of research assistants (RAs) will be trained to (A) conduct pre- and post-intervention sessions, (B) conduct intervention sessions, and (C) code verbal mediation data collected during the intervention session. The PI will inform members of Team B about participant assignments using controlled access features of the REDCap database. Teams A and C will be blinded as to whether children with DLD were in the training or control group.