Working memory profiles in Chinese children with reading and mathematics difficulties: Shared precision limitations but reduced span in comorbidity.

Working memory weaknesses in children with reading difficulties (RD) and/or mathematics difficulties (MD) have typically been assessed using span-based tasks, with limited attention to the precision of memory representations. This study examined working memory span and precision in Chinese third-grade children with learning difficulties and investigated how group differences varied as a function of memory load (set size). Using continuous color and orientation report tasks across four set sizes, working memory performance was quantified through mean absolute recall error (overall accuracy), the concentration parameter (precision) and the remember rate (span). Results revealed both shared and unique patterns across learning difficulty groups. First, all three learning difficulty groups showed reduced working memory precision in the easy set-size condition. Moreover, children with comorbid reading and mathematics difficulties (RDMD) demonstrated load-dependent performance declines, characterized by a steeper increase in absolute recall error as set size increased. This steeper increase may primarily stem from their limited working memory span, as evidenced by a consistently lower remember rate. These findings indicate that reduced working memory precision at low memory load is a shared feature across RD, MD, and RDMD, whereas this feature combined with reduced working memory span uniquely characterizes comorbid RDMD. Assessing both span and precision across varying set sizes provides a more detailed characterization of working memory profile than span measures alone.