PURPOSE: To determine whether word learning problems associated with developmental language impairment (LI) reflect deficits in encoding or subsequent remembering of forms and meanings. METHOD: Sixty-nine 18-25-year-olds with LI or without (ND) took tests to measure learning of 16 word forms and meanings immediately after training (encoding) and 12-hours, 24-hours, and 1-week later (remembering). Half of the participants trained in the morning and half in the evening. RESULTS: At immediate posttest, those with LI performed more poorly on form and meaning than those with ND. Poor performance was more likely among those with more severe LI. The LI and ND groups demonstrated no difference in remembering word meanings over one week. In both groups, participants who trained in the evening, and therefore slept shortly after training, demonstrated greater gains in meaning recall than those who trained in the morning. In contrast, the LI-ND gap for word form recall widened over the week. CONCLUSIONS: Some adults with LI have encoding deficits that limit the addition of word forms and meanings to the lexicon. Similarities and differences in patterns of remembering in the LI and ND groups motivate the hypothesis that consolidation of declarative memory is a strength for adults with LI.

Background and aims Previous investigations of word learning problems among people with developmental language disorder suggest that encoding, not retention, is the primary deficit. We aimed to replicate this finding; test the prediction that word form, not the linking of form to referent, is particularly problematic; and determine whether women with developmental language disorder are better word learners than men with developmental language disorder. Methods Twenty adults with developmental language disorder and 19 age-, sex-, and education-matched peers with typical language development attempted to learn 15 words by retrieval practice. Their retention was measured one day-, one week-, and one month after training. Results The participants with developmental language disorder required more exposures to the word-referent pairs than the participants with typical language development to reach mastery. While training to mastery, they made more errors in word form production, alone or in combination with errors in linking forms to the correct referents, but the number of no attempts and pure link errors did not differ by group. Women demonstrated stronger retention of the words than men at all intervals. The developmental language disorder and typical language development groups did not differ at the one-day- and one-month retention intervals but the developmental language disorder group was weaker at the one-week interval. Review via retrieval practice at the one-day and one-week interval enhanced retention at the one-month interval; the review at one week was more beneficial than the review at one day. Women benefitted more from the review opportunities than men but the developmental language disorder and typical language development groups did not differ. Conclusions Adults with developmental language disorder present with weaknesses in the encoding of new words but retention is a relative strength. Encoding word forms is especially challenging but encoding word-to-referent links is not. We interpret this profile, and the evidence of a female advantage, as consistent with the Procedural Circuit Deficit Hypothesis. Implications: When treating a client with developmental language disorder whose goal is to increase vocabulary knowledge, the interventionist should anticipate the need for multiple exposures to new words within activities that highlight the forms of the words and support their memory and production. Periodic review should serve to support long-term retention.

Purpose The aim of this study was to determine whether the word-learning challenges associated with developmental language disorder (DLD) result from encoding or retention deficits. Method In Study 1, 59 postsecondary students with DLD and 60 with normal development (ND) took the California Verbal Learning Test–Second Edition, Adult Version (Delis, Kramer, Kaplan, & Ober, 2000). In Study 2, 23 postsecondary students with DLD and 24 with ND attempted to learn 9 novel words in each of 3 training conditions: uncued test, cued test, and no test (passive study). Retention was measured 1 day and 1 week later. Results By the end of training, students with DLD had encoded fewer familiar words (Study 1) and fewer novel words (Study 2) than their ND peers as evinced by word recall. They also demonstrated poorer encoding as evinced by slower growth in recall from Trials 1 to 2 (Studies 1 and 2), less semantic clustering of recalled words, and poorer recognition (Study 1). The DLD and ND groups were similar in the relative amount of information they could recall after retention periods of 5 and 20 min (Study 1). After a 1-day retention period, the DLD group recalled less information that had been encoded via passive study, but they performed as well as their ND peers when recalling information that had been encoded via tests (Study 2). Compared to passive study, encoding via tests also resulted in more robust lexical engagement after a 1-week retention for DLD and ND groups. Conclusions Encoding, not retention, is the problematic stage of word learning for adults with DLD. Self-testing with feedback lessens the deficit. Supplemental Materials https://doi.org/10.23641/asha.5435200

Purpose To describe the word-learning problems characteristic of developmental language impairment (LI). Method College students with LI (n = 39) or normal language development (ND, n = 40) attempted to learn novel word forms. Training for half of the words was meaning-focused; training for the other half was form-focused. Form recognition and stem completion tasks administered immediately after training tapped encoding of the lexical configuration, and a repetition of the stem completion task one week later tapped consolidation. A visual world paradigm tapped lexical engagement. Result At the immediate posttest, the LI group was poorer at recognition and completion of word forms than their ND peers, suggesting a deficit in encoding the lexical configuration. However, the gap between the LI and ND groups in stem completion did not grow over the week, suggesting intact consolidation. Form-focused training yielded better performance than meaning-focused training at immediate- and one-week tests. For both groups, newly trained words slowed the recognition of familiar English words, revealing lexical engagement. Conclusion The encoding of word-form configurations is challenging for some, but not all, college students with LI. Training that encourages a focus on the form may be a useful part of vocabulary intervention for those affected.

Children with developmental language disorder (DLD) served as a test case for determining the role of extant vocabulary knowledge, endogenous attention, and phonological working memory abilities in cross‐situational word learning. First‐graders (Mage = 7 years; 3 months), 44 with typical development (TD) and 28 with DLD, completed a cross‐situational word‐learning task comprised six cycles, followed by retention tests and independent assessments of attention, memory, and vocabulary. Children with DLD scored lower than those with TD on all measures of learning and retention, a performance gap that emerged in the first cycle of the cross‐situational protocol and that we attribute to weaknesses in initial encoding. Over cycles, children with DLD learned words at a similar rate as their TD peers but they were less flexible in their strategy use, demonstrating a propose‐but‐verify approach but never a statistical aggregation approach. Also, they drew upon different mechanisms to support their learning. Attention played a greater role for the children with DLD, whereas extant vocabulary size played a greater role for the children with TD. Children navigate the problem space of cross‐situational learning via varied routes. This conclusion is offered as motivation for theorists to capture all learners, not just the most typical ones.