Accounting for individual differences in the development of verbal and visual short term memory processes in children

In developmental research on memory, the model of working memory of Baddeley and Hitch (1974, Baddeley, 1986) is the theory most often referred to. This theory has played an important role in studies on human learning in general. However, it is not clear how the verbal and visual short term memory systems develop. In order to investigate this development, we argue that some important issues should be taken into account; a longitudinal research design and individual differences between children. The current study is a follow-up study in which we investigated the transitions that a subsample of 30 children made between verbal and visual processing during the course of one year. Our results showed that the children showed large variation in STM processes and did not move from one type of processing to another in a consistent manner. This implies that the development of the verbal and visual STM systems may be less predictable than expected based on the literature, stressing the importance to be cautious when individual differences between children are not taken into account.