The Influence of Immersion Level and Cognitive Demand on Brain Dynamics: An EEG Microstates Analysis

Background: Cognitive resources are allocated based on task difficulty, duration and immersion level. The development of virtual reality (VR) technology, based on head-mounted displays (HMDs), has led to increased immersive user experiences, affecting mental load and effort, as measured by Electroencephalography (EEG). However, brain dynamics under different difficulty and immersive levels have not been fully described. Methods: EEG recordings and microstate (MS) analysis were used in classical desktop (DSK) and HMD-based stimulation environments to explore the effects of cognitive demand and immersion level on brain dynamics and their relationship with attention domains. Twenty-seven healthy participants performed a two-level N-back task in both environments, while EEG signals were acquired. Brain dynamics were evaluated through MS-based dynamic parameters and power-based indices were computed to estimate attention and engagement. Results: The increased task difficulty modulates EEG microstate dynamics, regardless of the immersion level. Specifically, the highest mental demand was associated with an increased presence of MS D, related to the task active network, confirming its involvement in cognitive tasks. Conclusions: Although immersion level did not significantly influence MS dynamics, it affected the relationship with attention level, with a stronger correlation observed in the DSK condition and a weaker one in the HMD scenarios.