Experiment 1 test results.

<p>Average speed (A) and accuracy (B) on exact, symbolic addition problems and approximate numerical comparison performance (C) by children in the two training conditions. Note: Performance accuracy in numerical comparison (C) is represented as a Weber fraction (<i>w</i>) derived from approximate, non-verbal numerical comparison performance, where smaller <i>w</i> values correspond to more precise ANS acuity.</p

Number line placement test performance by children in the three training conditions of Experiment 2.

<p>(A) Accuracy in ordinality of children's placements. (B) Proportion of children with more linear placements (dark portion of bars) and with more logarithmic placements (lighter portion of bars). (C) Proportion of error in children’s placements, with smaller values corresponding to better performance.</p

Experiment 2 training task results.

<p>Average reaction time (A) and accuracy (B) for the first (easier) and second (harder) set of training trials.</p

Schematic depiction of magnitude training conditions in Experiments 1 & 2.

<p>Numbers depict important time points beginning from the presentation of the first array (1) to the end of the trial (5).</p