Evidence for separate backward recall and n-back working memory factors: A large-scale latent variable analysis

Multiple studies have explored the factor structure of working memory (WM) tasks, yet few have done so controlling for the domain or category of the memory items. The primary aim of the current study, which was pre-registered, was to conduct a large-scale latent variable analysis using variant forms of n-back and backward recall tasks to test whether they measure the same underlying construct, or are distinguished by stimuli-, domain-, or paradigm-specific factors. Exploratory analyses that were not pre-registered explored how the resulting WM factor(s) were linked to fluid intelligence. Participants (N = 703) completed multiple web-based versions of n-back and backward recall tasks and a test of fluid reasoning. The memory tasks contained different memoranda that varied across (spatial or verbal material) and within (verbal digits or letters) domain, allowing the variance specific to task content and paradigm to be assessed. The data were best-captured by two distinct but related backward recall and n-back constructs, each linked to a separate fluid reasoning factor, in comparison to other plausible model constructions (including a single WM factor, or two-factor domain, and three-factor materials models). There were no differences in the strength of the relationship between each paradigm factor and fluid reasoning. Common variance associated with all WM tasks was a stronger predictor of fluid reasoning than a residual n-back factor, but the backward recall factor was an equally strong predictor of fluid reasoning as the common WM factor. These data emphasise the distinctiveness between backward recall and n-back tasks.