Purpose
Developmental dyslexia (DD) is commonly thought to arise from phonological impairments. However, an emerging perspective is that a more general procedural learning deficit, not specific to phonological processing, may underlie DD. The current study examined whether individuals with DD are capable of extracting statistical regularities across sequences of passively-experienced speech and non-speech sounds. Such statistical learning is believed to be domain-general, to draw upon procedural learning systems, and to relate to language outcomes.
Method
DD and control groups were familiarized with a continuous stream of syllables or sine-wave tones, the ordering of which was defined by high or low transitional probabilities across adjacent stimulus pairs. Participants subsequently judged two three-stimulus test items with either high or low statistical coherence as the most similar to the sounds heard during familiarization.
Results
Like control participants, the DD group was sensitive to the transitional probability structure of the familiarization materials, as evidenced by above-chance performance. However, DD participants’ performance was significantly poorer than controls across linguistic and non-linguistic stimuli. Additionally, reading-related measures were significantly correlated with statistical learning performance of both speech and non-speech material.
Conclusions
Results are discussed in light of procedural learning impairments among participants with DD.