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Computerized Stroop tasks have proven to be valuable tools in experimental and clinical psychology, providing reliable and reproducible assessments of cognitive processes. This paper presents the Influencer-Based Virtual Reality Stroop Test (IB-VRST), an innovative application that allows users to perform an immersive Stroop test while exposed to various virtual influencers. These influencers are categorized as task-related and non-task-related distractors, and elements of social presence implemented through competitive and collaborative virtual avatars. To validate this application and analyze the effects of these influencers on performance and stress levels, we conducted two experiments where we collected quantitative data using application logs and biometric sensors, and qualitative data using pre- and post-experiment questionnaires and self-reported stress ratings. Results show that IB-VRST successfully creates an immersive and intuitive experience that prompts the Stroop effect. While distractors generally impair performance and increase stress levels, social presence elements generally improve performance and reduce stress, except when participants compete against a more skilled opponent. This study adds to the existing literature by providing a comprehensive examination of the effects of virtual influencing factors on immersive Stroop tasks, thereby supporting the development of more engaging, immersive, and effective virtual Stroop tests.

Reducing energy consumption during walking is a critical goal for transtibial amputees. The study presents the evaluation of a semi-active prosthesis with five transtibial amputees. The prosthesis has a low-power actuator integrated in parallel into an energy-storing-and-releasing foot. The actuator is controlled to compress the foot during the stance phase, supplementing the natural compression due to the user’s dynamic interaction with the ground, particularly during the ankle dorsiflexion phase, and to release the energy stored in the foot during the push-off phase, to enhance propulsion. The control strategy is adaptive to the user’s gait patterns and speed. The clinical protocol to evaluate the system included treadmill and overground walking tasks. The results showed that walking with the semi-active prosthesis reduced the Physiological Cost Index of transtibial amputees by up to 16% compared to walking using the subjects’ proprietary prosthesis. No significant alterations were observed in the spatiotemporal gait parameters of the participants, indicating the module’s compatibility with users’ natural walking patterns. These findings highlight the potential of the mechatronic actuator in effectively reducing energy expenditure during walking for transtibial amputees. The proposed prosthesis may bring a positive impact on the quality of life, mobility, and functional performance of individuals with transtibial amputation.