Training Inner Speech 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.

SHIFTING TASK OVERVIEW: Each participant will complete three versions of a shifting task. The task is a modified dimensional change card sort (DCCS) task. The objective is to correctly sort stimulus images according to one of two rules, indicated by a visual cue. Each task will contain two sorting rules and a total of four bivalent stimulus images. Shifting rules will be simple and familiar concepts (i.e., color, shape, number, and size) for school-aged children. Cues will be the written name of each rule, for example "color," presented before each stimulus While participants are not expected to have any difficulty reading the rule names, the cue will be both spoken and written during all practice trials to eliminate any potential effects of word reading ability. To minimize demands on working memory, the written cue will remain on the screen while the stimulus is presented. The three task versions will have the same basic structure but different sets of rules and stimuli (counterbalanced across phases and participants). The task will always begin with two single-rule blocks, allowing children to practice each rule individually with a goal of learning to associate each rule with its cue and button response options. All shifting tasks will be computer-administered and presented using E-Prime 3.0 software. Responses will be collected using a Chronos response box. The NIH Toolbox version of the DCCS had excellent developmental sensitivity, test-retest reliability, and convergent validity in a sample of children aged 3-15 years. The DCCS has also been adapted for use with EEG in children, adolescents, and adults.

AIM 1 (TRAINING VS. CONTROL INTERVENTION): Determine the effects of modeling verbal mediation on the use of verbal mediation during a shifting task in children with DLD.

To achieve Aim 1, half of the participants in the DLD group will be exposed to an experimental verbal mediation training while the other half (and all TD participants) will be exposed to a control condition, embedded in a version of the shifting task.

Eliciting and recording verbal mediation during the intervention phase: The task design allows for eliciting and recording verbal mediation behavior before, during, and after the training or control conditions. Audio and video recordings will be used for offline coding and analysis of the participants self-directed spoken language. After exposure to each single-rule block, participants will complete several mixed-rule blocks with pre-randomized trials described below:

* Pre-/Post-Training: Participants will complete a total of 20 mixed-rule trials before training/control and 20 mixed-rule trials after. During these trials, all participants will be prompted to say what they are thinking and planning to do before they enter a response. Examiners will remind participants to speak out loud as needed but will not provide any language modeling. * Experimental training (modeling with verbal mediation): Participants will watch trials being completed while Max, a friendly character who knows the task very well, narrates his thoughts and actions to provide a model of effective verbal mediation. The language demonstrated will be future-oriented and structured as an implementation intention (i.e., if/then phrase) to support goal attainment. For example, participants will hear: "If this is the color game, then I should press the button for blue." An arrow will point toward the correct response. * Control (modeling only): These participants will watch Max complete trials with no verbal mediation spoken aloud (i.e., an arrow will point toward the correct response). This control condition will allow the isolation of the effect of verbal mediation training because both conditions provide the same modeling of actions. * Performance trials: In both the training and control conditions, every 10 modeling trials will be followed by 10 performance trials during which participants will be prompted to: "Tell Max what you plan to do before you do it." This alternating structure of modeling and performance will be repeated six times for a total of 60 model trials and 60 performance trials. This structure will allow the examination of change in verbal mediation throughout the intervention phase.

Verbal Mediation Measure: Each utterance, defined as a unit of speech with no temporal or semantic discontinuities (i.e., pauses greater than 2s or a change of content), will be coded for relevance and function. Relevance will be classified as: (a) irrelevant to the task, (b) relevant to task and self-directed, or (c) relevant to task but directed to examiner (e.g., asking questions to clarify rules, planned actions, etc.). Relevant utterances (b and c) will also be classified as one of three functions: (1) rehearsal, (2) regulating, or (3) affective. Rehearsal utterances would include simple statements of the rules or labeling of the stimulus. Regulating utterances would include the use of specific action verbs (e.g., switch) or the if/then framing provided in the model. Affective utterances would include emotional responses, evaluations of accuracy (e.g., oops), or mental states (e.g., I think…).

Fidelity Procedures: The PI will provide training on the coding procedures to study staff (RAs in Team C) who are blind to group membership. A random 25 percent of participants will be coded a second time to evaluate inter-rater reliability. The PI will monitor whether intraclass correlation for each utterance function category is greater than .75 and provide additional training as needed. Descriptive analyses will be used to quantify the amount of each utterance type produced. Relevant self-directed utterances produced during the 100 trials of Pre/Post-Training Verbal Mediation (20 trials pre, 20 trials post) and Performance (6 sets of 10 trials) will be further analyzed.

Data Analysis - Aim 1: To evaluate change in verbal mediation throughout the intervention phase, a random-intercept model will be performed with relevant utterance quantity regressed on (1) indicator for group (with DLD-control as the reference group; with parameters for the indicator for DLD-training and TD-control indicating differences for these groups from the reference group), (2) indicator for function of verbal mediation (with rehearsal as the reference group), (3) indicator for three task stages: pre-training (first 20 trials), training/control (60 performance trials) and post-training (last 20 trials), and (4) interaction of group indicator and task stage indicator (to evaluate differences between groups across stages). Multiple measures (of utterance quantity; controlling for utterance function) for each person will be accounted for by including the person-specific random intercept. Analysis will be conducted using RStudio and lme4 package. The investigators will also evaluate pre- and post-training differences in verbal mediation ability among children with and without DLD, by examining the number of each utterance type produced by all children with DLD (training + control) compared to TD-control participants using a series of independent samples t-tests with cluster-robust standard errors and using Bonferroni method to adjust for multiple comparisons.

Anticipated Results - Aim 1: modeling with verbal mediation will have a greater effect on the subsequent use of verbal mediation than modeling alone. Specifically, by the end of the intervention phase, it is expected that children in the DLD-training group will produce more relevant rehearsal and regulatory utterances than the DLD-control group, demonstrating more effective verbal mediation. The investigators also predict that at post-training, the DLD-training group will demonstrate fewer differences from the TD-control group than at pre-training; there will be a significant interaction between the relevant pairs of indicators. This comparison will serve to validate the novel o