Table 2.
Means and standard deviations of test scores by grade level.
| Task | Index | Mean(SD) | ||
|---|---|---|---|---|
| 3rd grade | 4th grade | 5th grade | ||
| Numerosity comparison | Percentage of correctness | 72.04(9.9) | 72.9(10.7) | 75.9(9.7) |
| Reaction time (millisecond) | 612(162) | 570(140) | 581(118) | |
| Figure matching | Percentage of correctness | 67.3(11.0) | 70.1(13.9) | 72.3(10.6) |
| Reaction time (millisecond) | 1008(290) | 965(253) | 938(180) | |
| Computational fluency | Adj. No. of correct trials | 26.2(4.6) | 28.8(5.1) | 30.5(5.7) |
| Verbal WM forward | No. of recalled digits | 7.6(1.2) | 8.1(1.3) | 8.2(1.3) |
| Visual tracing | Adj. No. of correct trials | 12.5(5.6) | 16.4(4.6) | 17.2(5.4) |
| Non-verbal matrix reasoning | Adj. No. of correct trials | 19.4(5.7) | 18.7(6.3) | 18.9(5.9) |
| Mental rotation | Adj. No. of correct trials | 17.9(8.2) | 20.7(7.7) | 20.9(7.8) |
| Choice reaction time | Reaction time (millisecond) | 433(133) | 423(126) | 421(152) |
| Mathematical achievement | Score(0–100) | 87.9(6.2) | 90.3(6.3) | 83.5(10.6) |
Adj. No. of correct trials = Total correct trials minus total incorrect trials. This adjustment was to control for the effect of guessing in multiple choice tests.