Alterations of Procedural Memory Consolidation in Children With Developmental Dyslexia

Objective: The objective of the present study was to determine if consolidation of procedural memory in developmental dyslexia (DD) may be supported by prolonging the initial learning session. Method: Children with DD (n = 31) and typically developing (TD) children (n = 34) were given a procedural (implicit sequence) learning task over two sessions, separated by a 24-hr interval. Session 1 was prolonged with 50% compared with previous studies of procedural memory consolidation in DD. Results: The amount of sequence learning was similar in the two groups at the end of Session 1 (p = .797, ηρ2 = .001). At the follow-up session after 24 hr, performance in the DD group was poorer compared with the TD group (p = .003, ηρ2 = .129). The amount of sequence knowledge in Session 2 predicted unique variance in reading fluency (p = .024, ηρ2 = 0.083), independent of children's phoneme awareness and inattention symptoms. Conclusion: The present study shows that consolidation of procedural memory is impaired in DD, even when the initial learning session is prolonged. The findings encourage further research on the mechanisms supporting procedural memory consolidation in children with DD, and how these may be strengthened. Key Points Questions: Is consolidation of procedural memory in children with developmental dyslexia normalized when the initial learning session is prolonged? Findings: The present study found alterations of procedural memory consolidation in children with developmental dyslexia despite a prolonged initial learning session. Importance: These findings suggest that the procedural learning problems previously observed in children with developmental dyslexia may be related to the overnight consolidation phase rather than to the initial learning phase. Understanding which aspects of learning that are particularly challenging in this condition is crucial to the development of effective intervention. Next step: The findings encourage further research on the mechanisms supporting memory consolidation in children with developmental dyslexia, and how these may be strengthened.