Breaking presence in Immersive Virtual Reality toward behavioral and emotional engagement.

BACKGROUND AND OBJECTIVE: Many recent studies in virtual reality (VR) have managed the sense of Presence to assess the suitability of their designs, mainly when focused on learning goals that require high user engagement, such as in serious games for psychomotor training. However, the place and plausibility illusions needed to promote Presence are achieved by combining different VR-based design cues, and their individual contribution to preserving the Presence's engagement/involvement component is still unclear. This article explored the single effect of breaking the sense of Presence per VR factor, i.e., removing VR cues related to Social Presence (human interactions), Self-Presence (embodiment), and Physical Presence (Scenario realism). METHODS: Thirty-three participants were asked to play an immersive VR simulation of an arcade game three times by experiencing a stepped Break of Illusion in one of the VR factors, i.e., while two factors were kept high, the remaining one was reduced to a low and null (hypothetical) level. The game difficulty was fixed after assessing each person's skills. RESULTS: Results showed that psychophysiology indicators (heart rate and skin conductance) were not affected by the level of illusion, whereas exercise intensity was significantly higher with low body and social presence-based conditions. Moreover, skin conductance was lower in the Social-presence group, which suggests that perspiration is only affected by breaks in realism (scenario and body representations). Based on the obtained evidence, we proposed some guidelines for adapting the design of immersive virtual environments through Breaks in Presence, mainly by changing the realism of the scenario and body representation depending on the skin conductance or the interaction with virtual humans depending on exercise intensity.

Dispositivo de medición de fuerza de los dedos y su rol en el seguimiento de las funciones de la mano / Device for measuring fingers strength and its role in monitoring hand functions

Introducción y objetivo: El amplio rango de movimiento y fuerza de la mano ha sido clave en el desarrollo de la especie humana dada su capacidad de adaptación según las demandas funcionales. El conocimiento de la anatomía y biomecánica de las estructuras que influyen en la generación de la fuerza de los dedos es crucial para el entendimiento de las alteraciones que pueden producir un deterioro de la misma. Son múltiples los estudios para valorar la fuerza de cada dedo y su rol en la funcionalidad del complejo sistema músculo-esquelético de la mano. En este trabajo descriptivo revisamos conceptos básicos y presentamos las etapas de diseño y construcción de un dispositivo tridimensional capaz de cuantificar de manera individual la fuerza de los dedos para la evaluación en pacientes sanos. Material y método: Realzamos múltiples mediciones en 20 pacientes sanos con un dispositivo que discrimina la fuerza de cada dedo y comparamos los resultados con estudios previamente publicados. Resultados: Los hallazgos numéricos de las diferentes mediciones son equiparables entre si y con los resultados en estudios previos. Conclusiones: Este nuevo dispositivo brinda la posibilidad de medir la fuerza de los dedos de manera individual, como valiosa herramienta en la evaluación del paciente sano y de pacientes con patologías traumáticas y no traumáticas, para cuantificar su grado de discapacidad, evolución postoperatoria o de su enfermedad de manera especifica al dedo comprometido y el impacto en la fuerza global de agarre. (AU)

Background and objective: The wide range of movement and strength of the hand have been key in the development of the human species given its ability to adapt according to functional demands. Knowledge of the anatomy and biomechanics of the structures that influence the generation of fingers force is crucial to understand the alterations that can cause its deterioration. Multiple studies have been conducted to assess the strength of each finger and its role in the functionality of the complex musculoskeletal system of the hand. In this descriptive paper, basic concepts are reviewed and stages of design and construction of a three-dimensional device capable of individually quantify the strength of each finger for healthy patients evaluation is presented. Methods: Multiple measurements were performed in 20 healthy patients with a device that discriminates the strength of each finger, comparing the results with previously published studies. Results: The results of the different measures are comparable with each other and with the results in previous studies. Conclusions:The use of this new device offers the possibility of measuring the strength of the fingers individually, which constitutes a valuable and novel tool in the evaluation of healthy patients and patients with traumatic and non-traumatic pathologies, to quantify their degree of disability, postoperative evolution or its disease specifically to the involved finger and its impact on the global grip strength. (AU)

A simplified method for online extraction of skin conductance features: A pilot study on an immersive virtual-reality-based motor task.

There is a growing body of literature that recognizes the importance of Skin Conductance (SC) for assessing changes in emotional states, such as engagement to learning tasks, and its importance to estimate possible drawbacks affecting overall performance. To date, most of the commonly used methods for SC signal analysis, i.e. detecting its phasic and tonic components and thus extracting informative features, are either too simple and unreliable or too complex and thus inaccessible and inflexible, as well as unable to perform online analyses. The current work proposes a simplified but clear and effective algorithm based on a Machine State to search for expected behaviors in the well-defined morphology of the signal. Eleven (11) features were correctly extracted from 79 healthy subjects during an experimental setup for immersive virtual rehabilitation (balance study case). The method was also successfully applied as a tool to identify significant changes in the subjective psychophysiological response to different experimental conditions. These results point toward a potential role in virtual rehabilitation applications by getting real-time feedback in human-in-the-loop approaches.

Effects of Presence and Challenge Variations on Emotional Engagement in Immersive Virtual Environments.

Serious games and immersive virtual reality promote emotional engagement during learning tasks, mostly by providing (1) skill-adapted challenges with performance feedback (for trial and error learning) and (2) enhanced presence (further reactions to multimodal stimuli), respectively. However, it is still unclear how each of these two strategies independently influence emotional states to engage subjects to a task. This study assessed the dimensions of emotion (valence-arousal-dominance) of 87 healthy subjects in a virtual game, assigned to 2 groups that were exposed to a different set of 5 trials: Group A experienced game variations by virtual factors affecting user's presence, whereas group B experienced levels of difficulty, affecting challenge. Emotional reports and 26 features extracted from physiological signals were statistically analyzed. Results showed that presence-based experimental conditions were able to modify the sense of arousal, whereas valence and dominance responded to challenge variation, i.e. were positively correlated with game score. Arousal is likely to increase with low sense of coexistence (social presence) and decrease with low scenario realism (physical presence). Faster breathing and higher skin conductance (SC) were detected at high challenge, whereas heart rate variability and SC increased with higher arousal. The evidence from this study suggests that both strategies can be used to separately influence dimensions of emotion, pointing out the customization of presence-based factors as a promising method to adjust emotional engagement by impacting arousal. Further research should be undertaken to identify the independent effect of single presence factors on emotional states.

Diseño y construcción de un dedo para grippers robóticos / Design and construcción of finger for robotic

En este trabajo muestra el diseño de un prototipo de dedo robótico antropomórfico un dedo artificial para la posterior implementación de una mano bio-mecatrónica. El dedo es desarrollado en el laboratorio de Automatización y Robótica de la Universidad Estatal de Campinas (Brasil) con la colaboración de la Universidad Militar Nueva Granada en Bogotá (Colombia). Una mano robótica multidedos típicamente tiene muchos grados de libertad (GDL), estos dedos están montados en una palma rígida, la cual está proyectada para ser ensamblada en la muñeca de un brazo robótico. El principal componente de una mano multidedos es el mecanismo de un dedo. Con base en el estudio de manos robóticas disponibles, es desarrollado un mecanismo para un dedo artificial el cual posee tres juntas y un GDL para todo el mecanismo. El mecanismo implementado es un sistema de palancas en donde la entrada es un tornillo sin fin para conversión de movimiento rotacional en lineal. Un prototipo del dedo es implementado y probado experimentalmente. Este diseño presenta una alternativa de bajo costo y permite la actuación y control de una mano artificial con un número pequeño de grados de libertad.

This work presents the design of a prototype of an anthropomorphic robotic finger (12). The main objective of this article is to show the design of an artificial finger. It describes the implementation of a finger for the implementation of a Bio- Mecatronic hand. The finger is developed in the “Laboratorio de Automatización y Robótica de la Universidad Estatal de Campinas (Brazil)” with collaboration with the “Universidad Militar Nueva Granada, Bogotá”, (Colombia). A robotic hand multi finger has many grades of liberty (GDL), these fingers are placed on a rigid palm, projected to be assembled in the wrist of a robotic arm. The main component of a multi finger hand is the mechanism of one finger. Based on the study of robotic hand available, a mechanism is developed for an artificial finger with three joints and one GDL for all the mechanism. The implemented mechanism is a system of levers where the entrance is a worm screw for the conversion of rotational movement into lineal. A prototype of a finger is implemented and tested experimentally. This design presents an alternative of low cost and allows the action and control of an artificial hand with some liberty.