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Transcranial direct current stimulation (tDCS) over the dorsolateral prefrontal cortex (DLPFC) has been shown to enhance divergent and convergent creative thinking. Yet, how stimulation impacts creative performance over time, and what cognitive mechanisms underlie any such enhancement, remain largely unanswered questions. In the present research, we aimed to (1) verify the impact of DLPFC tDCS on both convergent and divergent thinking, and further investigated (2) the temporal dynamics of divergent thinking, focusing on the serial order effect (i.e., the tendency for ideas to become more original and less frequent over time), and (3) any role that cognitive inhibition may play in mediating any effect of stimulation on creative thinking (considering the DLPFC’s involvement in driving inhibitory processes that are also relevant for creative thinking). In a within-subjects design, twenty-six participants received three types of cross-hemispheric tDCS stimulation over the DLPFC (left cathodal and right anodal, L-R+; left anodal and right cathodal, L+R-; and sham). Before stimulation, they completed a pre-flanker task measuring cognitive inhibition; during stimulation, they completed the Alternate Uses Task (AUT), Remote Associates Test (RAT), and post-flanker task. Results showed that, compared with the sham stimulation, originality of responses in the AUT was significantly enhanced in the L+R- condition, while no tDCS effect was observed for the RAT. Additionally, compared with the other stimulation conditions, we found a diminished serial order effect in the L+R- condition characterized by an accelerated production of more original ideas. Critically, the L+R- condition was accompanied by better performance on the flanker task. Our findings thus verify that L+R- tDCS over the DLPFC accelerates idea originality also providing tentative clues that inhibition may act as a cognitive mechanism underlying enhancements in divergent thinking resulting from frontal lobe neuromodulation. 

Semantic distance scoring provides an attractive alternative to other scoring approaches for responses in creative thinking tasks. In addition, evidence in support of semantic distance scoring has increased over the last few years. In one recent approach, it has been proposed to combine multiple semantic spaces to better balance the idiosyncratic influences of each space. Thereby, final semantic distance scores for each response are represented by a composite or factor score. However, semantic spaces are not necessarily equally weighted in mean scores, and the usage of factor scores requires high levels of factor determinacy (i.e., the correlation between estimates and true factor scores). Hence, in this work, we examined the weighting underlying mean scores, mean scores of standardized variables, factor loadings, weights that maximize reliability, and equally effective weights on common verbal creative thinking tasks. Both empirical and simulated factor determinacy, as well as Gilmer-Feldt’s composite reliability, were mostly good to excellent (i.e., > .80) across two task types (Alternate Uses and Creative Word Association), eight samples of data, and all weighting approaches. Person-level validity findings were further highly comparable across weighting approaches. Observed nuances and challenges of different weightings and the question of using composites vs. factor scores are thoroughly provided.