Fluid intelligence and working memory capacity: Is the time for working on intelligence problems relevant for explaining their large relationship?

• A large relationship between fluid ability and working memory is reported.
• This relationship is consistent across administration times of the fluid problems.
• High and low working memory individuals show great fluid ability differences.
• These differences widen with increased administration times of the fluid problems.

A recent report has shown that the relationship, at the latent variable level, between fluid ability and working memory capacity is affected by the time allowed for completing problems requiring the former (Chuderski, 2013): the greater the time, the lower the relationship. The underlying argument is that untimed administration of fluid ability problems compensates working memory capacity limitations. The present report analyzes a group of three hundred and two participants that completed a set of three fluid tests and six working memory tasks. Latent variable analyses revealed consistent correlations (weighted average r = .86) between fluid ability and working memory capacity irrespective of administration times. Furthermore, the lowest difference in fluid ability between individuals with high and low working memory capacity was observed for the highly speeded condition. Their difference was greater when increased time was allowed for completing the fluid problems. Therefore, the relationship between fluid ability and working memory capacity appeals to underlying general common mechanisms unrelated with time constraints. Here we suggest that the reliability by which the relevant information can be preserved in the short-term for successful on-line processing seems a likely candidate.