Table 2.

Behavioral effects of interventions. Estimated tDCS effect over sham in letter accuracy change, standard error (SE), 95% confidence interval (CI), and p-value at each post-intervention time point (After=immediately after intervention; 2wp=two weeks post-intervention; 2mp=two months post-intervention) using inverse probability weighting (IPW).

	Time	Estimate (SE)	95% CI	p-value
Trained items	After	0.74 (0.29)	(0.17, 1.32)	0.010
	2wp	0.68 (0.29)	(0.11, 1.25)	0.019
	2mp	0.85 (0.29)	(0.28, 1.42)	0.003
Untrained items	After	0.37 (0.28)	(−0.18, 0.92)	0.192
	2wp	0.23 (0.28)	(−0.32, 0.78)	0.409
	2mp	0.75 (0.28)	(0.19, 1.30)	0.008
(a) sham group
	Time	Estimate (SE)	95% CI	p-value
Trained items	After	0.80 (0.20)	(0.41, 1.19)	<0.001
	2wp	0.70 (0.20)	(0.31, 1.10)	<0.001
	2mp	0.47 (0.20)	(0.08, 0.86)	0.018
Untrained items	After	0.25 (0.19)	(−0.13, 0.63)	0.193
	2wp	0.34 (0.19)	(−0.04, 0.72)	0.079
	2mp	−0.00 (0.19)	(−0.38, 0.38)	0.994
(b) tDCS group
	Time	Estimate (SE)	95% CI	p-value
Trained items	After	1.55 (0.21)	(1.13, 1.97)	<0.001
	2wp	1.39 (0.21)	(0.97, 1.80)	<0.001
	2mp	1.32 (0.21)	(0.90, 1.74)	<0.001
Untrained items	After	0.62 (0.20)	(0.21, 1.02)	0.002
	2wp	0.57 (0.20)	(0.17, 0.97)	0.005
	2mp	0.74 (0.20)	(0.34, 1.15)	<0.001