Francesca Massa

Nowadays, modern manufacturing industries still rely on the expertise and manual dexterity of highly skilled operators. In this context, Mixed Reality (MR) technologies are emerging as promising solutions for contextualized task guidance to support operators during complex activities. However, their effective adoption in production environments is still limited by the lack of ergonomic evidence regarding their impact on operators’ well-being, usability, and interaction sustainability. This study investigates whether different interaction modalities with holographic instructional content influence the ergonomic suitability of a MR-based task guidance system for wire harnessing, developed in collaboration with Leonardo S.p.A. A between-subjects experimental design was adopted, involving 16 industrial workers randomly assigned to two groups: gaze and gesture interaction (Group A, n = 8), and gaze and voice interaction (Group B, n = 8). Ergonomic evaluation included both physical and cognitive aspects, assessed respectively through the Simulator Sickness Questionnaire (SSQ) and a composite usability index (UI) based on ISO 9241-11, integrating efficiency, effectiveness, and satisfaction. Results suggest comparable usability levels between the two interaction modalities (UI_A = 0.683; UI_B = 0.667). Gesture interaction was perceived as slightly more supportive of operational efficiency, whereas voice interaction was associated with lower cybersickness severity (mean TS_A = 331.5; TS_B = 196.1). Overall, the findings suggest that no single interaction modality universally outperforms the other, but rather that ergonomic suitability depends on the balance between physical workload, cognitive demands, and task characteristics. These results highlight the importance of human-centered ergonomic evaluations in the design of sustainable MR assistance systems for industrial environments.

Training for confined-space operations presents significant challenges due to safety risks, limited accessibility, and the complexity of reproducing realistic conditions. Within this context, immersive technologies such as Head-Mounted Display Virtual Reality (HMD-VR) offer a promising alternative for procedural training. This study evaluates the effectiveness of a hands-free, bimanual HMD-VR training system for confined-space operations as an alternative to physical training when access to real environments is constrained. Two HMD-VR configurations were investigated and compared with a physical training condition using a shared multi-step procedural scenario. Training outcomes were assessed across repeated executions and through a real-world evaluation, focusing on procedural performance and cognitive demand. Results show that all groups achieved significant improvements in performance over repeated executions, with reductions in completion time and error rate. Importantly, no statistically significant differences were observed between groups during the final real-world evaluation, and non-inferiority analyses confirmed that HMD-VR training did not result in performance outcomes worse than those achieved through physical training within predefined operational margins. Similarly, no significant differences emerged in either EEG-derived Cognitive Load (CL) or subjective workload at the final execution, despite a reduction in perceived workload over time. Analysis of subjective immersive experience revealed consistently high levels of presence and engagement across HMD-VR conditions, with no significant differences between configurations. However, spatial presence and perceived realism decreased over repeated exposure, suggesting an adaptation effect rather than a continuous increase in immersion. Overall, the findings indicate that, under the controlled conditions of this study, HMD-VR training enables real-world procedural execution and cognitive demand profiles comparable to those observed following physical training. These results support the potential of HMD-VR as a viable approach for novice procedural training in confined-space operations, particularly in contexts where traditional training is limited by safety, cost, or accessibility constraints.

Mixed Reality (MR) environments hold immense potential for inducing a sense of embodiment, where users feel like their bodies are present within the virtual space. This subjective experience has been traditionally assessed using subjective reports and behavioral measures. However, neurophysiological approaches offer unique advantages in objectively characterizing embodiment. This review article explores the current state of the art in utilizing neurophysiological techniques, particularly Electroencephalography (EEG), Photoplethysmography (PPG), and Electrodermal activity (EDA), to investigate the neural and autonomic correlates of embodiment in MR for out-of-the-lab applications. More specifically, it was investigated how EEG, with its high temporal resolution, PPG, and EDA, can capture transient brain activity associated with specific aspects of embodiment, such as visuomotor synchrony, visual feedback of a virtual body, and manipulations of virtual body parts. The potential of such neurophysiological signals to differentiate between subjective experiences of embodiment was discussed, with a particular regard to identify the neural and autonomic markers of early embodiment formation during MR exposure in real settings. Finally, the strengths and limitations of the neurophysiological approach in the context of MR embodiment research were discussed, in order to achieve a more comprehensive understanding of this multifaceted phenomenon.