LAUSR

Rational number understanding is a critical building block for success in more advanced mathematics; however, how rational number magnitudes are conceptualized is not fully understood. In the current study, we used a dual-task working memory (WM) interference paradigm to investigate the dominant type of strategy (i.e., requiring verbal WM resources vs. requiring primarily visuospatial WM resources) used by adults when processing rational number magnitudes presented in both decimal and fraction notation. Analyses revealed no significant differences in involvement of verbal and visuospatial WM, regardless of notation (fractions vs. decimals), indicating that adults rely upon a mix of strategies and WM resources when processing rational number magnitudes. However, this pattern interacted with algebra ability such that those performing better on the algebra assessment relied upon both verbal and visuospatial WM when engaging in rational number comparisons, whereas rational number performance by adults with low algebra fluency was affected only by a simultaneous verbal WM task. Together, results support previous work implicating the involvement of WM resources in rational number processing and is the first study to indicate that the involvement of both verbal and visuospatial WM, as opposed to relying primarily on verbal WM, when processing rational number magnitudes may be indicative of higher mathematical proficiency in the domain of algebra.