Motor learning and chunking in dyslexia.

The authors investigated whether participants with dyslexia had problems with executing discrete keying sequences and with switching between chunks in those sequences. Participants with dyslexia and participants in the control group executed 2 6-key sequences each, with 1 sequence consisting of 2 successive instances of 1 3-key segment (2 x 3 sequence) and the other not involving such a repetition (1 x 6 sequence). The authors assumed that during execution of the 2 x 3 sequence, the same chunk could be reused, whereas during execution of the 1 x 6 sequence a switch between chunks had to be made. Participants with dyslexia were slower than participants in the control group in executing the 1 x 6 sequence, but not the 2 x 3 sequence. The authors suggest that the smaller amount of repetitions of the chunks in the 1 x 6 sequence or the increased difficulty of the 1 x 6 sequence led to the slowed execution of the 1 x 6 sequence in participants with dyslexia.