Table A2.
Univariate Task Twin Correlations and ACE Estimates
| Task | Twin Correlationsa | Variance Components | Model Fit | ||||||
|---|---|---|---|---|---|---|---|---|---|
| MZ | DZ | A | C | E | χ2 (6) | p | RMSEA | CFI | |
| Antisaccade | .55 | .22 | .54 | .00 | .46 | 3.21 | .782 | .000 | 1.00 |
| Stop- signal | .51 | .08 | .44 | .00 | .56 | 10.41 | .109 | .061 | .911 |
| Stroop | .48 | .29 | .38 | .09 | .53 | 5.57 | .473 | .000 | 1.00 |
| Keep track | .54 | .25 | .53 | .00 | .47 | 1.89 | .930 | .000 | 1.00 |
| Letter memory | .57 | .18 | .55 | .00 | .45 | 7.50 | .277 | .035 | .983 |
| Spatial 2-back | .29 | .14 | .25 | .02 | .73 | 4.56 | .602 | .000 | 1.00 |
| Number–letter | .51 | .29 | .48 | .04 | .48 | 2.99 | .810 | .000 | 1.00 |
| Color–shape | .34 | .21 | .34 | .03 | .63 | 5.60 | .469 | .000 | 1.00 |
| Category switch | .53 | .33 | .39 | .13 | .47 | 3.47 | .748 | .000 | 1.00 |
| WAIS-IQ | .84 | .51 | .71 | .13 | .16 | 6.82 | .338 | .026 | .997 |
Note. A = additive genetic variance; C = shared environmental variance; E = nonshared environmental variance; RMSEA = root-mean-square error of approximation. CFI = confirmatory fit index. χ2/df < 2, RMSEA < .06, and CFI > .95 indicate good fit. Boldface type indicates p < .05. Italics indicate p < .10.