Koutaro Kamada

Generative AI (GenAI) is increasingly being integrated into creative work, either as a collaborator or as a replacement for human creators. More previous work has focused on augmenting users' creativity in the context of individual-GenAI collaboration. Humans often engage in group creative works across countless real-world contexts, yet the effects of GenAI on such group creativity remain largely unexplored, an urgent gap that demands immediate research attention. To address this gap as a first step, we conducted an electronic brainstorming experiment with three conditions in a within-subjects design: (A) groups of three participants without GenAI, (B) groups of three participants with GenAI, and (C) individual participants with GenAI (N = 24). In the results, GenAI-assisted group brainstorming significantly reduced the number of human-generated ideas, and did not significantly change the quality compared to brainstorming without GenAI. Plausible explanations for these are that reliance on GenAI is further increased in a group setting, and social loafing is more likely to occur. Therefore, we found that simply incorporating a GenAI agent does not necessarily lead to more effective human-GenAI co-creation in groups. On the other hand, compared to individual use of Gen AI, originality, elaboration, and flexibility improved significantly, so GenAI-assisted group brainstorming may have useful aspects. Based on our findings, we discuss the design implications of the strategy for leveraging GenAI effectively, future ideation methods, and creativity support systems. In particular, we suggest two interventions: 1) interactive idea generation, where humans and GenAI take turns combining and improving each others ideas, or 2) reducing over-reliance on GenAI. Our paper contributes to this domain by investigating the effects of human-GenAI collaboration in groups on brainstorming and providing design implications for more effective co-creation.