Inter-Brain Synchrony Levels According to Task Execution Modes and Difficulty Levels: An fNIRS/GSR Study

Area of Science:

• Neuroscience
• Cognitive Science
• Social Interaction Research

Background:

• Hyperscanning measures brain synchrony during social interactions, revealing significant inter-brain synchrony (IBS).
• The relationship between IBS and mental workload remains unclear.
• Understanding IBS drivers is crucial for social neuroscience.

Purpose of the Study:

• To investigate the link between inter-brain synchrony (IBS) and mental workload.
• To differentiate IBS caused by social interaction from other factors like task difficulty or physiological responses.
• To explore the role of cooperation and competition in modulating IBS.

Main Methods:

• Conducted hyperscanning experiments using functional near-infrared spectroscopy (fNIRS) and galvanic skin response (GSR).
• 56 participants performed button-pressing tasks at varying difficulty levels in cooperation and competition modes.
• Analyzed IBS in the 0.075-0.15 Hz frequency band and autonomic nervous system activity via GSR.

Main Results:

• IBS increased with task difficulty in cooperation mode, independent of task repetition frequency.
• Significant relative inter-brain synchrony (RIBS) increases were observed for harder tasks.
• Galvanic skin response (GSR) values increased with task difficulty only in competition mode.

Conclusions:

• Inter-brain synchrony (IBS) measured by fNIRS and GSR is not directly related to mental workload, simple behavioral synchrony, or autonomic nervous system activity.
• The findings suggest IBS is primarily driven by the social interaction itself, such as cooperation.