Do processing speed and short-term storage exhaust the relation between working memory capacity and intelligence?

The roles of processing speed (PS) and short-term storage (STM) for explaining the relationship between working memory capacity (WMC) and intelligence are analyzed at the latent variable level. 253 Chinese college students completed thirty-two measures from different content domains tapping the cognitive constructs of interest. The key findings showed that (a) PS accounts for the relationship between WMC and fluid intelligence, (b) STM and PS are required for explaining the correlation between crystallized intelligence and WMC. Therefore, this study provides support for the view that PS underlies the correlation between WMC and intelligence, yet with the nuance that its relevance decreases when cognitive tasks rely on crystallized knowledge and skill.