The development of working memory capacity and fluid intelligence in children

A longitudinal study was conducted to investigate the relationship between working
memory capacity and fluid intelligence and how this relationship develops in early childhood.
The major aim was to determine which aspect of the working memory system – short-term
storage or executive attention – drives the relationship with fluid intelligence. A sample of 119
children was followed from kindergarten to second grade and completed multiple assessments of
short-term memory, working memory, and fluid intelligence. Latent growth curve modeling was
employed to investigate the factor structure in each grade and to assess the stability of the factor
structure over time. The data suggest that working memory, short-term memory, and fluid
intelligence are highly related but separate constructs in young children and the factor structure
among these constructs is invariant across time. The results further showed that when the
common variance between working memory and short-term memory was controlled, the residual
working memory factor revealed significant links with fluid intelligence whereas the residual
short-term memory factor did not. These findings, consistent with previous research on young
adults, suggest that executive attention, rather than the storage component of working memory, is the primary source of the relationship between working memory capacity and fluid intelligence.