A multilevel meta-analysis on the causal effect of ANS training on symbolic math performance
The Approximate Number System (ANS) is hypothesized to play a foundational role in humans’ development of symbolic numerical representations and even the symbolic mathematical ability. However, studies attempting to investigate the causal relation between ANS and symbolic mathematical performance by training the latter and measuring the former have produced mixed findings. We systematically review the ANS training literature to investigate the strength of the effects of practicing ANS related tasks on symbolic math performance. Across 31 effect sizes from 9 studies involving 595 participants, for which neither the treatment nor control group received symbolic training, we found a small non-significant effect of ANS training on symbolic math task performance (g = .10, CI[-0.03, 0.22]). Some heterogeneity was accounted for by participant age, with larger estimates for adults than for children. Estimates did not vary significantly by ANS training type, training duration, and control group type. An exploratory analysis on the transfer effects of ANS training on untrained non-symbolic tasks suggests weak support for the key auxiliary assumption that ANS training has substantial effects on a general ANS, indicating that the training literature may not adequately represent theories on how ANS influences symbolic number performance.