Stability of computational deficits in math learning disability from second through fifth grades

This study utilized growth modeling to investigate the stability of two computational deficits that are strongly associated with math learning disability (MLD)-procedural deficits and fact fluency deficits. Math "deficit" was defined in two ways-having scores in the lower 10th percentile (MLD) and between the 11th and 25th percentiles (LA, low achieving). The longitudinal sample was composed of 214 children. Between the second and fifth grades, children who started at grade 2 with procedural deficits showed more rapid growth in procedural skills than typically achieving (TA) children. The procedural deficits group was able to narrow the initial gap in procedural skills and catch up with their normal peers. In contrast, children who started at grade 2 with fact fluency deficits showed the same growth in fact fluency skills as TA children. The fact fluency deficits group maintained their initial gap and was not able to catch up. This pattern of results held for both the MLD and LA criteria. Fact fluency deficits are more stable in the elementary years. Further results showed that fact fluency deficits may be associated with more pervasive and persistent cognitive deficits than procedural deficits. The fact fluency group showed persistent cognitive deficits in working memory, processing speed, and phonological processing, from grades 2-5. The group with procedural deficits at grade 2 showed persistent deficits in working memory and processing speed, but closed the gap in phonological skills. In addition, only the MLD procedural deficits group showed these cognitive deficits; the LA group was no different than the typical achievers. The present results support the hypothesis that fact fluency deficits and procedural deficits are dissociable and may represent distinct subgroups of MLD.