Table 1.

Means and standard deviations for variables

	Minimum	Maximum	M	SD	ttwin	tsex
Maternal negative affecta	2.79	46.00	22.74	9.93	0.76	0.80
Overanxious behavior	0.00	0.83	0.32	0.18	−0.54	−0.32
Morning cortisol	−3.38	0.08	−1.17	0.48	0.12	−1.26
Afternoon cortisol	−3.29	−0.86	−2.49	0.45	−0.14	0.37
Evening cortisol	−4.66	−1.26	−3.38	0.68	−0.05	1.74†
Baseline frontal asymmetry	−0.12	0.09	0.01b	0.04	0.55	3.35**
Stranger script frontal asymmetry	−0.18	0.24	0.02	0.07	−0.39	3.22**
Stranger conversation frontal asymmetry	−0.18	0.14	0.01	0.06	−0.51	1.82†
Experimenter conversation frontal asymmetry	−0.16	0.11	0.01	0.06	−1.05	0.48
Slopes of change in cortisol	−2.05	0.76	−1.11	0.46	−0.10	1.95†
Slopes of change in frontal asymmetry	−0.04	0.08	0.01	0.02	0.62	4.34**

Note: N = 98, Variables are on separate scales and are not intended for comparisons across measures or collection methods. t_twin is the result of an independent-samples t-test conducted to test for twin differences in variables. t_sex is the result of an independent-samples t-test conducted to test for sex differences in variables.

^aImputation models do not force imputed scores into an interval scale, which occasionally results in a subset of values that are not whole numbers. We prefer to use the true imputed values rather than rounding to the nearest whole number.

^bValues are truncated to two decimal places for presentation purposes. However, given the small scale of the EEG data, asymmetry values included 14 decimal places for analyses.