Retrieval-Based Word Learning in Developmental Language Disorder: Verb Learning

Children with developmental language disorder (DLD; also referred to as specific language impairment) experience a significant deficit in language ability that is longstanding and harmful to the children's academic, social, and eventual economic wellbeing. Word learning is one of the principal weaknesses in these children. This project focuses on the word learning abilities of four- and five-year-old children with DLD. The goal of the project is to build on the investigators' previous work to determine whether, as has been found thus far, special benefits accrue when these children must frequently recall newly introduced words during the course of learning. The focus of the current study is verb-learning. The goal of the study is to increase children's absolute levels of learning while maintaining the advantage that repeated retrieval holds over comparison methods of learning.

Developmental Language Disorder (DLD) affects language learning in an estimated 7% of children. Although much of the research literature has emphasized difficulties learning grammar, children with DLD also have major deficits in vocabulary. In recent work, the investigators have been examining the benefit of retrieval practice to enhance word learning and retention in preschoolers with DLD. The rationale behind this work is grounded in the growing literature in the field of cognitive psychology which shows that repeated practice in retrieving information results in greater long-term retention than continuous study of that information without opportunities for retrieval. In addition, retrieval practice that occurs after a delay-or "spacing" between study of a word and subsequent recall attempts-can lead to stronger effects. The investigators have explored the benefits of retrieval practice for preschoolers with DLD and with typical language development (TD), showing that recall and retention for novel words (nouns, adjectives, verbs) were greater when learned using repeated spaced retrieval (RSR) than when learned using repeated study only. Despite benefitting from RSR, children with DLD still showed lower levels of recall than children with TD, in particular in novel verb learning. In the current study, the investigators seek to improve the absolute levels of word form recall for verbs by modifying the method used previously. Sixteen children with DLD will be recruited for this study along with 16 children with TD matched on chronological age. Using a within-subjects design, children will learn eight novel verbs, four at a time. Each set of four will be learned over two consecutive days, with two words in the RSR condition and two words in a repeated study condition. The referents for these novel words will be video-recorded transitive actions performed by actors on objects and presented on a laptop screen. In the RSR condition, children will initially hear the word paired with a video of a novel action, immediately be asked to recall the word, and then see/hear it again. After three other words are presented, they will be asked to recall the original word again; this "3" spaced retrieval schedule will continue for the rest of the learning session. In the comparison condition, children will simply hear the words paired with a video of the novel action. In this study, during retrieval practice, children will be prompted to respond with a full sentence containing the verb. Recall of the verbs will be tested after the learning session on the second day and one week later. At one week, children will also complete a syntactic generalization test in which they are prompted to use the novel verb in a type of sentence that is different from the one used during learning. Finally, children will complete a two-alternative recognition test. The investigators hypothesize that novel verbs that undergo RSR during the learning period will be learned and recalled better than comparable novel verbs that are assigned to the repeated study condition. This RSR advantage will continue to be observed when the children must use the novel verbs with new actors and objects and will be seen as well in the syntactic generalization test when the children must use the novel verbs in a new sentence frame. Introducing novel verbs representing actions that can be performed on varying objects is expected to improve overall learning. In addition, by having the child produce the verbs in the context of a full sentence, the newly learned verbs should become more integrated with other sentence elements (subjects and direct objects), resulting in a richer representation in memory and consequently, greater recall, recognition, and syntactic flexibility than was observed in the previous novel verb study.

Each child will learn 8 novel verbs referring to unfamiliar transitive actions ("mape"). Four verbs will be learned in a condition requiring spaced retrieval practice; four verbs will be learned in a "standard" study-only (no retrieval practice) condition. In the spaced retrieval condition, the number of other words intervening between hearing the target and an attempt to retrieve it will increase from 0 to 3 words. In the study-only condition, children will simply hear the verb used to describe the action.

Learning sessions: Novel verbs are practiced on Day 1. In one condition, the words are learned using repeated spaced retrieval practice - retrieval trials are initially immediate, then occur after 3 intervening words. In the other condition, the words and video are presented without retrieval trials. This practice schedule is repeated the next day (Day 2). Testing sessions: 5 minutes after the learning session on Day 2, the child is asked to recall each word in the context of a sentence twice with actors and objects viewed during learning and twice with new actors and objects. One week after Day 1, this recall test is completed again. At this time, the child's ability to generalize the verb to a new sentence frame will be assessed. Finally, the child will complete a recognition test: viewing pairs of video clips, the child will hear each novel verb and point to the video clip that depicts that action.

Child is asked to recall and use the verb associated with each novel action in a sentence (X is VERBing the Y).

Child is asked to recall and use the verb associated with each novel action in a sentence (X is VERBing the Y).

Accuracy of generalizing novel verb to a new syntactic frame (number of verbs used in a syntactic frame different from the one used in initial learning and recall).

Upon hearing a novel word, the child is asked to indicate (by pointing) which video among 2 options is referred to.

Upon hearing a word, the child is asked to indicate (by pointing) which picture among 4 options is referred to.

Primary care-giver provides information regarding highest academic degree attained, converted to years of education

Inclusion Criteria: a significant deficit in language ability (language test score below cutoff for best sensitivity/specificity) or documented age-appropriate language ability. normal hearing no evidence of neurological damage or disease scores on tests of nonverbal intelligence above the intellectual disability range not within Autistic range on Autism screening test native English speaker (can be bilingual) Exclusion Criteria: failed hearing screening known neurological damage or disease scores on tests of nonverbal intelligence below the intellectual disability range (standard score less than 75) autism spectrum disorder non-native English speaker

Data that contribute to our final published results will be made available at www.clinicaltrials.gov.

Data will become available after the results are published or within 12 months from the primary completion date (i.e., the date of final data collection for the primary outcome measure).