Encoding Deficits Impede Word Learning and Memory in Adults with Developmental Language Disorders

• Published in: Journal of speech, language, and hearing research language, and hearing research, 2017-10, Vol.60 (10), p.2891-2905
• Main Authors: McGregor, Karla K, Gordon, Katherine, Eden, Nichole, Arbisi-Kelm, Tim, Oleson, Jacob
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Adults; Cognition & reasoning; Cognitive Processes; College Students; Cues; Developmental Disabilities; Evidence; Executive Function; Experimental psychology; Familiarity; Feedback; Health aspects; Humans; Language; Language acquisition; Language Development Disorders - psychology; Language disorders; Language Impairments; Language Tests; Learning; Learning Disabilities; Learning Problems; Long Term Memory; Memory; Memory Disorders; Novelty (Stimulus Dimension); Pattern Recognition, Visual; Phonology; Physiological aspects; Recall; Recall (Psychology); Recognition (Psychology); Retention; Retention (Psychology); Schizophrenia; Semantics; Semiotics; Short term; Short Term Memory; Speech; Speech Perception; Speech-language pathology; Students; Time Factors; Verbal Ability; Verbal Learning; Verbal Tests; Vocabulary; Vocabulary learning; Word Recognition; Young Adult; Young adults
• ISSN: 1092-4388; 1558-9102; 1558-9102
• DOI: 10.1044/2017_JSLHR-L-17-0031

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. 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.