Creativity and semantic control: cognitive and neural insights from divergent thinking to discourse production

Abstract

Effective semantic processing is governed by two interacting neural systems: the representational system and the semantic control system. The representational system stores semantic knowledge, while the semantic control system manipulates this stored knowledge to extract task-relevant information. These flexible retrieval mechanisms are essential for various cognitive functions, including creativity. Creativity is believed to stem from a dynamic interplay between bottom-up associative processes, which rely on semantic memory during idea generation, and top-down executive control processes during idea evaluation, ensuring goal maintenance and inhibition of dominant responses. Despite neuroimaging studies underscoring the importance of semantic control regions in creativity, this area remains underexplored in the cognitive literature.

This thesis explores the role of semantic control mechanisms in creative thinking. The aims of the first study were twofold: to explore the contributions of semantic knowledge and control abilities to creative performance in divergent and convergent thinking tasks, beyond domain-general cognitive mechanisms; and, to investigate age-related variations in semantic and executive abilities, and their impact on creative thinking. The findings indicated that divergent and convergent thinking rely on different aspects of semantic cognition. Specifically, convergent thinking was found to be reliant on semantic knowledge, whereas divergent thinking depended more on semantic control. This distinction was particularly evident in the young group, suggesting that younger individuals may engage their semantic control mechanisms more, while older people may rely on domain-general mechanisms of processing speed and inhibition.

Building on these findings, the second study sought to further dissect the cognitive mechanisms underlying creative thought. Specifically, the study investigated whether performance on divergent and convergent thinking tasks could be explained by individual differences in the ability to generate and evaluate ideas. A detailed analysis of the idea generation process was conducted to understand how different retrieval strategies relate to creative performance, with a focus on the role of clustering (retrieving related items) and switching (transitioning between different clusters) in semantic search. The results indicated that ability to generate multiple ideas enhances creative fluency, but strict evaluation may hinder the originality of responses. Moreover, the findings suggested that multiple retrieval strategies influence creative performance. Broad sampling of the semantic space is generally beneficial for creative success, but the optimal strategy involves balancing exploitation of specific areas of the semantic space and exploration of new areas to maximize creative output.

The third study explored the role of semantic control in a more cognitively complex and ecologically valid realm: the production of extended naturalistic speech. Effective and interesting discourse requires the generation of diverse ideas, but also crucially depends on the ability to organise these ideas logically into a coherent narrative. Previous work has established the role of various brain networks, including the Default Mode Network, Executive Control Network and Semantic Control Network in supporting these processes, but the interplay between them in spontaneous speech has been largely unexplored. To this end, the third study investigated how creativity and coherence are related at the behavioural level, and the neural mechanisms supporting these aspects of communication. A negative association between the two constructs was found at the behavioural level, highlighting the cognitive balance required to produce speech that is both interesting and comprehensible. Network activation analyses indicated that more coherent speech was related to increased engagement of the Multiple Demand Network, supporting the role of cognitive control processes in the maintenance of coherent speech. Moreover, functional connectivity analyses indicated that divergence in speech was related to increased functional connectivity between the default and executive networks, aligning with previous work demonstrating default-executive coupling during creativity tasks.

Collectively, the results of these studies highlight the multifaceted role of semantic control in creativity, demonstrating that it is a critical cognitive mechanism that is differentially engaged to support the generation, evaluation, and organization of original ideas.