Improvement in creativity after transcranial random noise stimulation (tRNS) over the left dorsolateral prefrontal cortex

Creativity has previously been shown to improve after the application of direct and alternating current transcranial stimulation over the dorsolateral prefrontal cortex (DLPFC). However, previous studies have not tested whether transcranial random noise stimulation (tRNS) was efficient for this purpose. The aim of this randomized, double-blind, placebo-controlled study was to investigate the effect of tRNS on both verbal convergent and (verbal and visual) divergent thinking during left DLPFC tRNS stimulation. Thirty healthy participants were randomly allocated to either a tRNS active group or a sham group. Each session lasted 20 min and the current was set to 1.5 mA (100-500 Hz). Participants' verbal convergent thinking was assessed with the Remote Associates Test (RAT). Verbal and visual divergent thinking were respectively measured by using the Unusual Uses and Picture Completion subtests from the Torrance Tests of Creative Thinking. Bootstrapped analysis of variance showed significant differences in the mean change scores between the active tRNS group and the sham group in RAT scores (d = 1.68); unusual uses: fluency (d = 2.29) and originality (d = 1.43); and general creativity (d = 1.45). Visual divergent thinking, in contrast, did not show any significant improvement. Our results suggested that tRNS over the left DLPFC is effective for increasing verbal divergent and convergent thinking.