Universal and differential effects of prefrontal transcranial electrical stimulation on convergent and divergent thinking.

Creativity is a high-level cognitive process that includes convergent and divergent thinking. The dorsolateral prefrontal cortex (DLPFC) and inferior frontal gyrus (IFG) are key nodes of the executive control system and are implicated in creativity. Transcranial electrical stimulation (tES) techniques, including transcranial direct current stimulation (tDCS) and transcranial random noise stimulation (tRNS), have been shown to modulate creative thinking. However, most existing research is focused on the stimulation of single brain regions or unilateral hemispheres, and comparative effects of various tES techniques remain unclear. Therefore, we conducted a randomized single-blind study with stimulation electrodes placed over the left DLPFC and right IFG. A total of 110 participants were randomly assigned to one of four groups (tDCS, tRNS, tDCS-tRNS, or sham) and each received 22 min of online stimulation. The results showed that all active stimulation groups (tDCS, tRNS, tDCS-tRNS) enhanced convergent thinking performance. In contrast, the divergent thinking showed stimulation-specific effects. tDCS enhanced the originality of verbal divergent thinking, while the tRNS improved fluency in figural divergent thinking. The tDCS-tRNS stimulation showed no improvement in divergent thinking. These results support the effectiveness of tES in improving convergent thinking and highlight the need for targeted approaches to modulate specific aspects of divergent thinking.