Table 1.
The age adjusted mean scores, standard deviations, sample sizes, F-values and effect sizes for the four twin groups (Mm, Mf, Fm and Ff) after randomly selecting one twin per pair.
| Measure | Mm | Mf | Fm | Ff | F | η 2 |
|---|---|---|---|---|---|---|
| Spatial Ability Total | 0.50 (0.92) 342 | 0.44 (0.92) 167 | −0.14 (0.87) 220 | −0.31 (0.96) 695 | 71.41** 1424 | 0.13 |
| Bricks Total | 0.19 (0.71) 699 | 0.10 (0.72) 360 | −0.03 (0.61) 448 | −0.12 (0.66) 1410 | 36.04** 2917 | 0.04 |
| Bricks 2D | 0.18 (0.76) 699 | 0.09 (0.76) 360 | −0.01 (0.70) 448 | −0.11 (0.73) 1410 | 25.64** 2917 | 0.03 |
| Bricks 3D | 0.21 (0.81) 693 | 0.12 (0.82) 353 | −0.05 (0.68) 438 | −0.12 (0.76) 1390 | 31.24** 2874 | 0.03 |
| Cross Sections | 0.30 (1.00) 635 | 0.19 (1.04) 337 | −0.16 (0.96) 446 | −0.14 (0.96) 1290 | 37.89** 2708 | 0.04 |
| Elithorn Mazes | 0.35 (0.93) 556 | 0.38 (0.89) 296 | −0.06 (0.87) 373 | −0.26 (1.02) 1077 | 66.75** 2302 | 0.08 |
| Mechanical Reasoning | 0.43 (1.00) 621 | 0.37 (0.95) 329 | −0.22 (0.93) 425 | −0.24 (0.93) 1236 | 93.53** 2611 | 0.10 |
| Shape Rotation | 0.26 (0.97) 567 | 0.22 (0.98) 301 | −0.06 (0.95) 395 | −0.16 (1.00) 1155 | 29.84** 2418 | 0.04 |
| Perspective Taking | 0.42 (1.11) 572 | 0.40 (1.15) 299 | −0.17 (0.87) 399 | −0.25 (0.83) 1165 | 86.83** 2435 | 0.10 |
| Mazes | 0.26 (1.00) 580 | 0.20 (0.95) 306 | −0.11 (1.01) 393 | −0.15 (0.97) 1132 | 28.16** 2411 | 0.04 |
| 2D Drawing | 0.30 (0.90) 627 | 0.19 (0.95) 336 | −0.12 (0.96) 442 | −0.16 (1.04) 1278 | 36.46** 2683 | 0.04 |
| 3D Drawing | 0.37 (0.99) 565 | 0.21 (1.04) 299 | −0.16 (0.92) 388 | −0.18 (0.96) 1146 | 48.91** 2398 | 0.06 |
| Pattern Assembly | 0.23 (1.02) 607 | 0.25 (0.99) 324 | −0.09 (0.96) 420 | −0.15 (0.97) 1231 | 28.83** 2582 | 0.03 |
| Paper Folding | 0.20 (1.00) 589 | 0.18 (1.04) 313 | −0.03 (0.98) 420 | −0.13 (0.98) 1198 | 18.75** 2520 | 0.02 |
The total sample size for each task is reported under the F-value.
Note. Mm = Males with a male co-twin; Mf = Males with a female co-twin; Fm = Females with a male co-twin; Ff = Females with a female co-twin; F-value represents the variation explained by the mean differences between four twin groups; Eta-squared (η2) is the value for the effect size; All the tests were standardized for the whole sample (males and females combined) with a mean of 0. Analyses were then run on these standardized values for males and females separately. For all measures, males’ average scores were positive and females’ average scores were negative.
**p < 0.01.