Evidence of compensatory processing in adults with developmental language impairment: Testing the predictions of the procedural deficit hypothesis

Abstract

Background The Procedural Deficit Hypothesis (PDH) proposes that individuals with primary developmental language impairment (DLI) have a deficient procedural memory, compromising their syntactic abilities. Individuals with DLI may compensate for procedural memory deficits by engaging declarative memory for syntactic tasks. Arguments are part of the lexicon whereas adjuncts rely on syntactic processing. As a result, individuals with DLI may have unusual difficulty processing adjuncts. Alternatively, processing for adjuncts may be typical for individuals with DLI but show frequency effects, indicating compensatory use of declarative memory. Aims Our goal was to test the predictions of the PDH by comparing argument and adjunct processing times for adults with and without DLI, and to seek evidence of compensatory use of declarative memory for adjunct processing. We further evaluated group performance on measures of visual procedural and declarative memory. Methods & Procedures Forty-four adults, 21 with DLI, completed a self-paced listening task, a procedural memory task, and a declarative memory task. The self-paced listening task tracked the word-by-word processing time for sentences that included prepositional phrases acting as arguments or adjuncts. We used regression analysis to determine effects of group membership and argument or adjunct status on processing times. Correlation analyses evaluated relationships between argument and adjunct frequency on processing times by group. Results & Outcomes We found no effect of group membership on the processing time for arguments and adjuncts in the self-paced listening task. Argument phrases were processed more easily by both groups. There were frequency effects for adjunct processing for the group with DLI, but not the group with typical language. We did not find the expected frequency effects for argument processing. The group with DLI also performed more poorly in both the procedural and declarative memory tasks. Secondary analyses found that non-verbal intelligence was related to outcomes on the declarative memory but not the procedural memory task. Conclusions & Implications We found mixed evidence on the predictions of the PDH. Adults with DLI may compensate for procedural memory deficits but it is unclear whether this depends on declarative memory or language processing experience. Compensatory processing is an important element of the language profile for adults with DLI.

Episodic memory retrieval in adolescents with and without developmental language disorder (DLD)

“…, Poll et al . , Kuppuraj et al . ), whereas others found that children with DLD did not have difficulty associating two unrelated non‐verbal items together (Bishop and Hsu ).…”

“…With regard to non-verbal declarative memory in DLD, results are also mixed. Some work reported spared nonverbal declarative memory in children with DLD (Baird et al 2010, Bishop and Hsu 2015, Lum et al 2012, whereas others found poor performance on non-verbal declarative memory tasks in DLD (Bavin et al 2005, Kuppuraj et al 2016, Poll et al 2015. Two possible reasons may explain these inconsistent findings.…”

“…The paired associates learning paradigm, which entails pairing of two unrelated items, is one of the most widely used experimental tasks to index episodic memory in the DLD literature. Several researchers showed impaired associative learning of non-verbal information in individuals with DLD (e.g., Bavin et al 2005, Kuppuraj et al 2016, Poll et al 2015, whereas Bishop and Hsu (2015) found that children with DLD did not have difficulty associating two unrelated non-verbal items together. Kuppuraj et al (2016) suggest that this discrepancy lies in the nature of memory retrieval demanded by different tasks.…”

“…Memory recall involves more activated brain regions than memory recognition, and thus places higher demands on the brain (Cabeza et al 1997). In Bavin et al (2005), Kuppuraj et al (2016), and Poll et al (2015), memory retrieval was assessed via spontaneous recall; in contrast, in Bishop and Hsu (2015), memory retrieval was assessed via recognition, which may explain, at least partially, why children with DLD performed comparably to their age-matched peers.…”

“…(), and Poll et al . (), memory retrieval was assessed via spontaneous recall; in contrast, in Bishop and Hsu (), memory retrieval was assessed via recognition, which may explain, at least partially, why children with DLD performed comparably to their age‐matched peers.…”