Application of the dual-component model of working memory to ADHD:Greater secondary memory deficit despite confounded cognitive differences

Abstract

The dual-component model postulates that working memory capacity consists of two dissociable components: maintenance in primary memory (PM) and retrieval from secondary memory (SM). Recent application of this model to attention-deficit/hyperactivity disorder (ADHD) has revealed that the SM component is more deficient than the PM component across both verbal and spatial modalities. The present study attempts to strengthen this conclusion by addressing two weaknesses in the previous study. First, the present study shows that the SM component continues to be more deficient than the PM component across both modalities under conditions in which (1) all participants were instructed to use the same recall strategy (resulting in the exclusion of fewer participants); and, (2) individual differences in this strategy were controlled. Second, the present study also documents a group difference in word reading efficiency that is confounded with diagnostic status and that might have influenced estimates of PM and SM capacities in the verbal modality. However, although the SM component is more deficient than the PM component in the ADHD group, the magnitude of this interaction does not vary as a function task modality. These findings are interpreted to suggest that the pattern of WM deficiencies observed are part of a causal pathway that can lead to the symptoms of ADHD, as well as to impairments in reading (and intelligence) due to overlapping cue-dependent retrieval mechanisms. These findings provide additional support for the notion that the SM component of WM is an important and neglected target for treatment.

Working memory and short-term memory deficits in ADHD: A bifactor modeling approach.

“…Our estimates of short-term memory were derived from tasks with prominent executive components (storage ϩ processing). Thus, although results were generally consistent with findings from alternative assessment methods (e.g., simple span, immediate free recall; Dovis et al, 2013;Gibson et al, 2018), it remains possible that short-term memory deficits would be detected/larger on tasks that require simple storage without active mental manipulation of the internally stored information, although at the same time such tasks would be expected to significantly underestimate working memory (Wells et al, 2018). Similarly, the current study did not evaluate the ability to maintain information in short-term memory over extended durations or assess the episodic buffer.…”

“…Thus, the bifactor-(s-1) model allows maximal discrimination between our constructs of interest, therefore providing a direct test of the extent to which working memory test scores reflect reliable variance attributable to both domain-general central executive processing (working memory) and domain-specific phonological and visuospatial storage/rehearsal (short-term memory) processes (Eid et al, 2018). By fractionating test performance into reliable variance associated with all three primary components of the Baddeley (2007) model, this approach provides the ideal test of the extent to which ADHD is associated with specific short-term memory deficits when accounting for their well-documented impairments in working memory, as recommended (Gibson & Gondoli, 2017; Gibson et al, 2018).…”

“…To address this limitation, Gibson et al (2018) used phonological and visuospatial immediate free recall (IFR) tasks, and scored children's recall based on established primacy and recency effects, to differentiate between performance attributed to primary memory (i.e. short-term memory) and secondary memory (i.e.…”

Working memory and information processing in ADHD: Evidence for directionality of effects.

“…Although this finding must be interpreted with caution because of the unsupportive omnibus effect, it may be that information processing speed serves to facilitate the maintenance of information within working memory only when children are attempting to preserve more items than they can store in short-term memory. Alternatively, it may be that processing speed provides a better fit for modeling short-term memory rather than working memory (i.e., in relation to items degrading from passive storage over time rather than top-down/secondary memory processes involved in actively manipulating or retrieving these items after they have been lost; Gibson, Gondoli, Ralph, & Sztybel, 2018).…”

ADHD reflects impaired externally directed and enhanced internally directed attention in the immediate free-recall task.

“…Here we assessed EDC and IDC as a function of diagnostic status (ADHD vs. control) by combining and reanalyzing the verbal IFR results previously reported by Gibson et al (2010) and Gibson et al (2018). We fit the RCM to the PFR, SPC, and lag-CRP.…”