Attentional Requirements During Acquisition and Consolidation of a Skill in Normal Readers and Developmental Dyslexics

Objective: Previous research demonstrated that individuals with developmental dyslexia (DD) may suffer from a deficit in the acquisition stage of a new skill, whereas consolidation processes seem to be preserved. The present study was designed to examine whether this impaired acquisition was attributable to a lack of automatization, and whether the reported preserved consolidation was attributable to the use of DDs' conscious compensation strategies. These aims were implemented by testing a skill-learning task in dyslexics and normal readers using a dual task paradigm. The impact of dual task costs on participants' performance was used as an indication for automaticity. Method: DD and control groups completed a sequence-learning task over a first session (acquisition) and a second session 24 hours later (consolidation). The task was performed by half of the participants under a full attention condition and by the other half under a divided attention condition. Results: Consistent with previous reports in the literature, divided attention impaired sequence learning in both groups. Nevertheless, divided attention resulted in delayed acquisition of the motor skill in the DD group compared with normal readers. Finally, divided attention enhanced motor procedural consolidation only in the control group. Conclusions: The differential effect of divided attention on acquisition and consolidation of procedural skill in DD and normal readers supports the cerebellum deficit hypothesis in DD. In addition, the enhanced skill consolidation in normal readers under divided attention suggests that attentional requirements are not necessary for all types of human learning.