Sequential learning, domain generality, and developmental dyslexia

This thesis explores sequential learning, the implicit learning of item sequences with a specific statistical structure. Two research questions were investigated. The first is whether sequential learning is a domain-general learning mechanism. Both 8-month-old infants and adults were tested on their sequential-learning capabilities in more than one domain. The infants were tested in the (auditory) language and in the visuospatial domains, the adults also in the visual domain. Neither the infant nor the adult experiments provided a conclusive answer to this question, because performance on sequential learning did not correlate significantly or strongly across domains in either age group. The second research question is whether sequential learning is affected in developmental dyslexia. Both 8-month-old infants at familial risk of dyslexia and adults with dyslexia were tested in the same sequential-learning experiments as their peers without (a risk of) dyslexia. Results related to this question were mixed. The at-risk infants showed an indication of visuospatial sequential learning that was not observed in the typically developing infants. More research is needed to interpret this outcome. In adults with dyslexia, somewhat poorer performance of language sequential learning was found. No clear differences between adults with and without dyslexia were found in the visual and visuospatial experiments. The question of the domain generality of sequential learning could not be decisively answered, and no support was obtained for a general deficit in sequential learning in dyslexia. The results may, however, point to slightly reduced sequential-learning capabilities in the language domain in adults with dyslexia