Figure captions:
Fig. 1 Flow diagram of participant’s eligibility assessment
Fig. 2 A flow diagram of the serial response time testing conditions during pre-test, main test, and post-test
Fig. 3 Reaction Time (RT, Mean ± SEM) of blocks during serial response time test (SRTT) training in (A) 1mA M1 a-tDCS group, (B) 2mA M1 a-tDCS group, (C) 1mA M1 c-tDCS group, (D) 2mA M1 c-tDCS group, (E) sham M1 tDCS group, Error Rate (ER, Mean ± SEM) of blocks during SRTT training in (F) 1mA M1 a-tDCS group, (G) 2mA M1 a-tDCS group, (H) 1mA M1 c-tDCS group, (I) 2mA M1 c-tDCS group, (J) sham M1 tDCS group; * indicates significant differences within group
Fig. 4 A The post-hoc analysis comparison of online learning (changes in RT between blocks 3 and 10): a-tDCS (1mA) Vs. c-tDCS (1 mA) group (p=0.001), a-tDCS (1 mA) Vs. sham tDCS group (p=0.01), c-tDCS (1 mA) Vs. a-tDCS (2 mA) group (p=0.01);, offline learning (changes between blocks 2 and 12): a-tDCS (1 mA) with c-tDCS (1 mA) group (p=0.01), a-tDCS (1 mA) with sham tDCS group (p=0.02) and consolidation effect of learning (changes between blocks 10 and 12) among groups; B the comparison of online learning (changes in ER): a-tDCS (1 mA) Vs. sham tDCS group (p=0.037); offline learning: a-tDCS (1 mA) Vs. c-tDCS (1 mA) group (p=0.001), c-tDCS (1 mA) Vs. c-tDCS (2 mA) group (p=0.03), a-tDCS (2 mA) Vs. c-tDCS (1 mA) group (p=0.001), a-tDCS (1 mA) Vs. sham tDCS (p=0.002) group, a-tDCS (2 mA) Vs. sham tDCS group (p=0.028) and consolidation effect of learning among groups (Mean differences ± SEM)