Private speech use in arithmetical calculation: relationship with phonological memory skills in children with and...

The majority of recent studies conclude that children's private speech development (private speech internalisation) is important for mathematical development and subject to disabling. The main concern of the present study was whether or not the two phonological memory factors evaluated in the study (i.e. the results of children's digit span assessments, both forward and backward) relates to private speech internalisation and whether this relationship changes with children's age, or mathematical achievement levels, or both. We made comparisons between children with acknowledged mathematical difficulties (MD) and children without mathematical difficulties (MN), basing on private speech differences, phonological memory differences and differences in the relationship between private speech internalisation and phonological memory skills. The results not only confirm the impact of private speech internalisation but also emphasise a possible parallel role of phonological memory for subsequent mathematical achievement. In contrast to the MD children, children without MD showed an age-determined shift from a lesser to greater relationship between a high level of private speech internalisation and a high level phonological memory skills. As a whole, the results are consistent with a developmental difference and not with a developmental delay model and suggest that relationships between private speech internalisation and phonological memory may reflect individual differences in children's mathematical achievement. The results are discussed in terms of directions for future research.