Table 5. Standardized Factor Loadings and 95% Confidence Intervals of Multivariate ACE, AE, and ADE Analyses.
| Shared environmental effects included | Shared environmental effects omitted | Shared environmental effects omitted, dominance genetic effects included | ||||||
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| A | C | E | A | E | A | D | E | |
| Genetic and Environmental Contributions to the Higher Order EF Factor | ||||||||
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| Common EF | 1.00*** (1.00, 1.00) | .00 (.00, .00) | .00 (-.05, .05) | 1.00*** (1.00, 1.00) | .00 (-.01, .01) | .88*** (.52, 1.23) | .48 (-.21, 1.17) | .08 (-.61, .77) |
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| Genetic and Environmental Contributions Unique to Individual EF Domains | ||||||||
| Inhibition | .00 (.00, .00) | .00 (.00, .00) | .75 (-.12, 1.61) | .00 (.00, .00) | .70 (-.46, 1.87) | .00 (.00, .00) | .00 (.00, .00) | .60 (-1.49, 2.70) |
| Switching | .59*** (.29, .89) | .00 (.00, .00) ( | .15 -1.09, 1.39) | .59*** (.29, .89) | .15 (-1.08, 1.38) | .00 (.00, .00) | .62*** (.43, .81) | .00 (.00, .00) |
| Working Memory | .00 (.00, .00) | .00 (.00, .00) | .38** (.14, .62) | .00 (.00, .00) | .37** (.12, .61) | .00 (.00, .00) | .00 (.00, .00) | .36** (.09, .62) |
| Updating | .00 (.00, .00) | .00 (.00, .00) | .24* (.03, .46) | .00 (.00, .00) | .24* (.03, .46) | .00 (.00, .00) | .00 (.00, .00) | .26* (.05, .47) |
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| Genetic and Environmental Contributions Unique to Individual Tasks | ||||||||
| Animal Stroop | .47*** (.25, .68) | .00 (.00, .00) | .78*** (.65, .92) | .47*** (.25, .68) | .79*** (.65, .92) | .00 (.00, .00) | .57*** (.35, .79) | .72*** (.55, .89) |
| Mickey | .00 (.00, .00) | .26 (-.04, .56) | .92*** (.81, 1.02) | .26 (-.15, .68) | .92*** (.79, 1.05) | .26 (-.16, .68) | .00 (.00, .00) | .92*** (.79, 1.05) |
| Stop Signal | .00 (.00, .00) | .28* (.04, .51) | .95*** (.88, 1.02) | .19 (-25, .62) | .97*** (.88, 1.06) | .18 (-.26, .63) | .00 (.00, .00) | .97*** (.89, 1.06) |
| Trail Making | .33*** (.14, .52) | .00 (.00, .00) | .63*** (.52, .74) | .33*** (.14, .52) | .63*** (.52, .74) | .00 (.00, .00) | .38*** (.21, .55) | .60*** (.51, .70) |
| Plus-Minus | .00 (.00, .00) | .00 (.00, .00) | .95*** (.91, 1.00) | .00 (.00, .00) | .95*** (.91, 1.00) | .00 (.00, .00) | .32 (-.47, 1.11) | .90*** (.62, 1.18) |
| Local-Global | .26* (.02, .51) | .00 (.00, .00) | .76*** (.67, .85) | .26* (.02, .51) | .76*** (.67, .85) | .00 (.00, .00) | .34* (.04, .63) | .73*** (.60, .86) |
| Symmetry Span | .38* (.01, .76) | .15 (-.58, .87) | .63*** (.53, .73) | .42*** (.29, .54) | .62*** (.54, .71) | .41*** (.28, .54) | .00 (.00, .00) | .63*** (.54, .71) |
| Listening Recall | .00 (.00, .00) | .00 (.00, .00) | .64*** (.57, .70) | .00 (.00, .00) | .64*** (.57, .70) | .00 (.00, .00) | .00 (.00, .00) | .64*** (.57, .71) |
| Digit Span Back | .43*** (.28, .59) | .00 (.00, .00) | .72*** (.64, .81) | .43*** (.28, .59) | .72*** (.64, .81) | .33 (-.32, .98) | .31 (-.48, 1.09) | .72*** (.61, .82) |
| Running Memory | .17 (-.12, .46) | .00 (.00, .00) | .54*** (.45, .64) | .17 (-.12, .46) | .54*** (.45, .64) | .00 (.00, .00) | .28** (.07, .49) | .51*** (.40, .61) |
| N-Back | .44*** (.30, .57) | .00 (.00, .00) | .62*** (.52, .71) | .44*** (.30, .57) | .62*** (.52, .71) | .34 (-.18, .86) | .32 (-.34, .97) | .60*** (.48, .71) |
| Keeping Track | .30** (.10, .50) | .00 (.00, .00) | .69*** (.60, .78) | .30** (.10, .50) | .69*** (.60, .78) | .00 (.00, .00) | .33** (.12, .53) | .68*** (.57, .78) |
Note. EF = executive function, A = additive genetics, C = shared environment, E = non-shared environment, D = dominance genetics. Our model controls for age-effects at the level of the first-order factors (Inhibition, Switching, Working Memory, and Updating). Because the purpose of this analysis was to understand the relative contributions of genetic and environmental influences to individual differences, as separate from age-related differences, the loadings of the first-order factors have been standardized relative to their age-independent variance.
*
p ≤ .05,
**
p ≤ .01,
***
p ≤ .001.