Asymmetric activation spreading in the multiplication associative network due to asymmetric overlap between numerosities semantic representations?

Simple multiplication facts are thought to be organised in a network structure in which problems and solutions are associated. Converging evidence suggests that the ability for solving symbolic arithmetic problems is based on an approximate number system (ANS). Most theoretical stances concerning the metric underlying the ANS converge on the assumption that the representational overlap between two adjacent numbers increases as the numerical magnitude of the numbers increases. Given a number N, the overlap between N and N + 1 is larger than the overlap between N and N − 1. Here, we test whether this asymmetric overlap influences the activation spreading within the multiplication associative network (MAN). When verifying simple multiplication problems such as 8 × 4 participants were slower in rejecting false but related outcomes that were larger than the actual outcome (e.g. 8 × 4 = 36) than rejecting smaller related outcomes (e.g. 8 × 4 = 28), despite comparable numerical distance from the correct result (here: 4). This effect was absent for outcomes which are not part of either operands table (e.g., 8 × 4 = 35). These results suggest that the metric of the ANS influences the activation spreading within the MAN, further substantiating the notion that symbolic arithmetic is grounded in the ANS.