Performance in symbolic and non-symbolic comparison before and after training. a) Symbolic comparison (Arabic digit) accuracy, plotted as a function of the distance between the numbers (measured by their log ratio). A slight change in shape in the post curve suggests an increase in precision of the quantity representation. b) Symbolic comparison (Arabic digit) reaction time. A significant decrease is seen between pre and post curves in overall RT (p = 0.002). c) Non-symbolic comparison (dot clouds) accuracy. A significant increase in accuracy at post test (p = 0.01) suggests a more precise representation of numerosity. d) Non-symbolic comparison (dot clouds) reaction time. A significant decrease is seen in overall RT (p = 0.006). Note: Error bars indicate one standard error.