Table 2.

Studies on tCS and creativity.

Study	Creative process	Technique	Parameters/location	Duration	Design	Paradigm	Results
Chi and Snyder, 2012	Insight	tDCS	1.6 mA (30 s raising), electrode 35 cm2 Anode: right ATL Cathode: left ATL	10 min	Within-participants: pre-during-post Between: active vs. sham	9-dot problem	40% of the active group were able to solve the problem; none of the sham group solved it
Chi and Snyder, 2011	Insight	tDCS	1.6 mA (30 s raising) electrode 35 cm2 Anode: right ATL Cathode: left ATL	10 min	Between participants: (1) L− R+; (2) L+ R−; (3) Sham stimulation	Matchstick problems	60% of the participants in the L-R+ group were able to solve the difficult problems whereas lower than 20% in the other groups solved it
Metuki et al., 2012	Insight	tDCS	1 mA (30 s raising) electrode 35 cm2 Unilateral active Anode: left DLPFC (F3); Cathode: right OFC (Fp2)	11 min (5 min pre + 6 online)	2 × 2Within-participants: (1) Active vs. sham (sessions separated by a week); (2) Easy vs. Hard	RAT (CRA) with limited time (to investigate solution identification rather than generation)	They found that stimulation did not affect the rate of solution for either hard or easy problems. However, they found an interaction between stimulation and difficulty for solution recognition, as the participants in the active stimulation group were more able to recognize correct solutions for hard problems
Cerruti and Schlaug, 2009	Insight	tDCS	1 mA Anode: 16.3 cm2 Cathode: 30 cm2 Experiment 1 Anode: left DLPFC Cathode: right OFC Experiment 2 Anode: left DLPFC Cathode: right DLPFC	20 min 16 min stimulation + 4 min stimulation during the verbal fluency task	Within-participants design with (3 h session): (1) Anodal electrode location: F3 vs. right supraorbital region (Experiment 1); F3 vs. F4 (Experiment 2); (2) Condition: active anodal, active cathodal, sham	Verbal Fluency (VF) + RAT (CRA) with 30 s to solve	They found that the stimulation did not improve VF, but was associated with higher solution rates when the stimulated area was above the left DLPFC. The two experiments showed the same result, with higher solution rates for anodal on the left DLPFC
Chrysikou et al., 2013	Divergent thinking (flexible tool use)	tDCS	1.5 mA 25 cm2 electrodes Cathode: F7 or F8 Anode: on the contralateral mastoid (the main purpose was to cause inhibition of PFC)	20 min (including 10 s ramp-up + 10 s ramp down). Stimulation began for 180 s prior to the tasks	Between-subjects design with two factors: Stimulation protocol (groups): (1) Cathodal Left (F7) and anodal on mastoid; (2) Cathodal Right (F8) and anodal on mastoid; (3) Sham Task (groups): (1) Common uses; (2) Uncommon uses	Div. Thinking: participants were asked to generate either (1) common vs. (2) uncommon uses for the objects presented on the screen (60 grayscale pictures). Each participant was assigned to only one of these two conditions. The performance was measure to response onset time	There was a significant interaction between stimulation protocol and task condition, since cathodal over the left PFC was associated with in an decrease in the response times for the uncommon uses task. There was no difference in performance between stimulation conditions in the common uses task. In addition, cathodal stimulation over the left PFC was associated with lower number of response omissions in the uncommon uses task only (no difference in the common uses task)