Problem-solving and cooperation: from individual insight to dyadic hyperscanning

Problem-solving is a fundamental cognitive ability that supports human adaptation, innovation, and everyday functioning. Rather than representing a single cognitive process, it emerges from the interaction between executive control, associative mechanisms, analytical reasoning, and creative insight. Moreover, problem-solving often occurs in social contexts, where individuals coordinate their actions and jointly construct solutions. A comprehensive account of problem-solving should therefore integrate both individual cognitive mechanisms and the neural dynamics that support interpersonal coordination. This Ph.D. thesis investigates problem-solving through a dual-aspect framework that combines cognitive psychology and cognitive neuroscience. The project examines problem-solving at two complementary levels: the individual-cognitive level, focused on creative insight and associative recombination, and the social-interactive level, focused on cooperative problem-solving and neural coordination between individuals. The first study addresses the individual dimension of problem-solving by introducing and validating the Combination of Images Task (CIT), a novel non-verbal paradigm designed to investigate visuospatial insight problem-solving. Moving beyond the traditional reliance on verbal tasks, the CIT assesses whether the recombination of remote concepts can elicit the characteristic “Aha!” experience in a visual domain. Behavioral findings support the validity of the task and suggest that associative recombination represents a domain-general mechanism of creative insight, extending its investigation beyond language-based cognition. The second study examines cooperative analytical problem-solving from a second-person neuroscience perspective. A novel cooperative figural puzzle task was developed for dual-EEG hyperscanning, allowing the investigation of Leader-Follower dynamics, turn-taking, within-brain oscillatory activity, and inter-brain synchrony during joint action. Behavioral results showed that Leaders required longer response times than Followers, suggesting greater cognitive demands during the initiation of cooperative sequences. EEG analyses revealed role-specific oscillatory patterns, including increased central gamma power in Leaders during action execution and higher alpha/mu activity in Followers during observation-related phases. Inter-brain synchrony analyses further indicated frequency-specific and phase-dependent neural coupling between partners, reflecting reciprocal adaptation during the construction and evaluation of a shared problem space. Overall, this thesis shows that effective problem-solving relies on integrative mechanisms operating both within and between individuals. At the individual level, solutions emerge through the associative recombination of remote concepts; at the interpersonal level, cooperative problem-solving is supported by dynamic neural coordination and oscillatory synchronization. By linking these two levels through novel experimental paradigms, this work contributes to cognitive psychology, cognitive neuroscience, and social neuroscience, providing behavioral and neural markers that may inform future assessment and training approaches aimed at enhancing cognitive and social flexibility.