Background. Creativity is generally associated with positive valence. Many researchers have revealed that positive affect would promote divergent thinking, especially in individual work with one single task. However, the relationship between affect and creative performance in practical group project setting has been poorly understood. In fact, creative work is very often conducted in groups, through several working phases including divergent and convergent tasks. Moreover, a group involved in creative tasks often faces not only challenges on conducting cognitive tasks but also challenges related to group collaboration. The gathering of people to achieve a goal will evoke the emergence of leadership behavior. Emergent leadership may also influence affective experiences of the group members. However, influence of emergent leadership on performances as well as affective experiences of people during creative tasks have not been well studied. This study aims to reveal how affects of group members and emergent leadership influence group creative performance. In this study, arousal was hypothesized as a significant affective factor related to activation of group members' participation in tasks to generate various ideas, as well as valence. Furthermore, leadership was hypothesized as another significant factor related to managing group affective atmosphere and regulate cognitive performance.

Methods. The empirical study was conducted in a graduate course on design thinking in an engineering school. Seventeen graduate students participated in this study voluntarily. The course was a project-based learning program aimed to learn design process. The current study concentrated on five phases, including seven group work activities of creative tasks. The seven tasks consisted of both divergent thinking such as opportunity finding, ideation, prototyping, and dark-horse prototyping, and convergent thinking such as synthesis, concept development, and storytelling. Participants' affect and leadership perception were measured at the end of every creative task, using the Self-Assessment Manikin and the Leadership Behavior Questionnaire, respectively. Outputs of creative tasks were evaluated by five individual raters, not including any of the participants nor the authors, to yield the scores for performance of creative tasks. The divergent task outputs were rated and scored along the three criteria: uncommon, remote, and cleverness. The convergent task outputs were rated and scored with three criteria: similarity, serendipity, and mediation. The relationship among affects and emergent leadership perception of participants, and performance scores of creative tasks were analyzed.

Results. Results showed coherency between performance of divergent tasks and affects of participants, especially for arousal. A series of Spearman's rho tests showed significant positive correlation between arousal and overall divergent performance in ideation and prototype task, as well as valence and cleverness in prototyping task. Mann-Whitness U test exhibited that groups with moderate-to-high arousal average scores achieved higher performances in divergent tasks than groups with low arousal scores in most of the divergent tasks. Meanwhile, correlation between negative valence and higher convergent performance was found only in one task of concept development. Amongst emergent leadership variables, relationship-oriented leadership was positively correlated with affects, although it was not correlated significantly with task performance. Meanwhile, task-oriented leadership showed positive correlation with valence in the storytelling task and positively correlated with performance in some of the convergent tasks.

Conclusion. Affect and emergent leadership were found to be related to group creative performance in different ways. Performance of divergent tasks was found to be better with medium-to-high arousal. Meanwhile, the task-oriented leadership was found to be associated with better performance in convergent tasks.

Added-Values. This study revealed the further understanding of how group based creative work differs from individual based creative work in terms of relation with affects. Previous studies revealed the role of positive valence in individual divergent performance. Meanwhile, arousal emerges as the strong factor to support group divergent performance in the current research. Furthermore, the results implies the importance of the leadership in group creative work. The appropriate understanding of emergent leadership may support group creative processes.

Keywords: valence; arousal; emergent leadership; divergent thinking; convergent thinking.