Andrea Brogni

Analysis of physiological responses to a social situation in an immersive virtual environment

An experiment was conducted in a Cave-like environment to explore the relationship between physiological responses and breaks in presence and utterances by virtual characters towards the participants. Twenty people explored a virtual environment (VE) that depicted a virtual bar scenario. The experiment was divided into a training and an experimental phase. During the experimental phase breaks in presence (BIPs) in the form of whiteouts of the VE scenario were induced for 2 s at four equally spaced times during the approximately 5 min in the bar scenario. Additionally, five virtual characters addressed remarks to the subjects. Physiological measures including electrocardiagram (ECG) and galvanic skin response (GSR) were recorded throughout the whole experiment. The heart rate, the heart rate variability, and the event-related heart rate changes were calculated from the acquired ECG data. The frequency response of the GSR signal was calculated with a wavelet analysis. The study shows that the heart rate and heart rate variability parameters vary significantly between the training and experimental phase. GSR parameters and event-related heart rate changes show the occurrence of breaks in presence. Event-related heart rate changes also signified the virtual character utterances. There were also differences in response between participants who report more or less socially anxious.

Variations in physiological responses of participants during different stages of an immersive virtual environment experiment

This paper presents a study of the fine grain physiological responses of participants to an immersive virtual simulation of an urban environment. The analysis of differences in participant responses at various stages of the experiment (baseline recordings, training, first half and second half of the urban simulation) are examined in detail. It was found that participants typically show a stress response during the training phase and a stress response towards the end of the simulation of the urban experience.There is also some evidence that variations in the level of visual realism based the texture strategy used was associated with changes in mental stress.

Sharing and analyzing data from presence experiments

Presence research relies heavily on empirical experiments involving subjects in mediated environments. Since presence is a complex, multidimensional concept, experiments on presence can be extremely resource intensive and produce large amounts of data of different types. As the presence community matures, we would like to suggest that data collected in experiments be made publicly available to the community. This will allow the verification of experimental results, comparison of results of experiments carried out in different laboratories, and evaluation of new data-analysis methods. This will, eventually, lead to consistency in approaches and increased confidence in results. In this paper we present the complete dataset from a large-scale experiment that we have carried out in highly immersive virtual reality. We describe the data we have gathered and give examples of the types of analysis that can be made based on that data.

Comparative usability and performance evaluation of surgeon interfaces in laser phonomicrosurgery

Robot-assisted surgical procedures, such as Laser Phonomicrosurgery (LP), suffer from susceptibility to variation in surgeon skill and equipment characteristics. Ergonomic and human-centered approaches acquire increased importance in the design of surgeon-machine interfaces. This paper proposes a protocol for comparative evaluation of surgeon-machine interfaces based on two criteria: (i) the subjective evaluation of their usability using questionnaires, and (ii) the objective evaluation of their performance using an imaging-based feature extraction method. Two interfaces in LP, the traditional (“AcuBlade”) interface and the novel (“Virtual Scalpel”) interface, were evaluated to demonstrate the effectiveness of the proposed scheme. A series of experimental trials were conducted using the interfaces in surgery-like tasks in a controlled environment. The subjective evaluation pointed to the superiority of the Virtual Scalpel interface (score: 83.06) in terms of confidence and ease of use, and learnability, over the AcuBlade interface (score: 65.56). The objective evaluation showed the Virtual Scalpel interface having an overall score (55.96) significantly superior to the AcuBlade (51.37). It is thus shown that the multidimensional evaluation approach allowed to clearly distinguish between levels of perceived usability and effective performance of surgeon-machine interfaces from a user-centered perspective.

Pervasive services and mobile devices may support human memory and enhance daily efficiency

A service capable of supporting human memory requires complex computational tasks that are still unavailable in mobile devices; however, broadband connectivity allows weaving together server side computational power with client side rich content delivery. In this paper, we provide a complete description of the 4W (what-where-when-who) project and its current prototype. The system aims at providing a service that mitigates the negative effects of stress or aging on the memorisation capability of humans leveraging both client side and server side state of the art solutions. The prototype is capable of capturing user needs/to-dos, reasoning to identify where those needs/tasks can be fulfilled/performed efficiently and providing timely and localised hints about the identified sweet-spots. We have tested with real users both the general efficacy of the system and the different level of efficiency of several hint-notification modes: we present our results and we provide a discussion of our findings.

Imaging based metrics for performance assessment in laser phonomicrosurgery

State-of-the-art laser phonomicrosurgery (LP) used for the treatment of laryngeal abnormalities involves complex otolaryngological surgical techniques. It relies heavily on surgeon dexterity, requiring significant psychomotor skills. Equipment scale and size, laser operative distance, and the anatomically small nature of the vocal folds all combine to compound the surgical challenges. An objective measurement is therefore necessary to understand the impact of equipment design, its usability, surgeon skill, and learning, on performing LP effectively. This paper introduces imaging based feature extraction as a method to establish metrics to assess surgical performance in LP. Experimental analysis demonstrates the utility of these metrics in measuring surgical task execution vis-à-vis the task objectives. The metrics also provide for a combined rating scale giving a robust quantitative classification of the levels of surgical performance.

Enhancing Personal Efficiency with Pervasive Services and Wearable Devices

The recent developments in pervasive services offer incredible opportunities to provide a host of efficiency enhancement to human users. In fact, although complex computational tasks still require server side resources, combination of rich content delivering devices, such as smart phones, together with wearable I/O devices and wireless broadband networking, can be used to seamlessly weave a mesh of client side and server side services. In this paper we describe how we leveraged such a set up to design and build a system capable of mitigating the negative effects of stress on the memorization capability of humans. Our system is able to capture user needs and to-dos, to infer where those needs and tasks can be efficiently fulfilled/performed and to provide timely and localized hints about the identified sweet-spots. Furthermore we evaluated innovative ways to drive the user to the most convenient site. We describe our system and a modular design both on the client and on the server sides, illustrating preliminary experiments performed both in laboratory and with real users, and we analyze the results.

Touching sharp virtual objects produces a haptic illusion

Top down perceptual processing implies that much of what we perceive is based on prior knowledge and expectation. It has been argued that such processing is why Virtual Reality works at all - the brain filling in missing information based on expectation. We investigated this with respect to touch. Seventeen participants were asked to touch different objects seen in a Virtual Reality system. Although no haptic feedback was provided, questionnaire results show that sharpness was experienced when touching a virtual cone and scissors, but not when touching a virtual sphere. Skin conductance responses separate out the sphere as different to the remaining objects. Such exploitation of expectationbased illusory sensory feedback could be useful in the design of plausible virtual environments.

Distractive User Interface for Repetitive Motor Tasks: A Pilot Study

Innovative design features of user interfaces could assist a patient during the accomplishment of repetitive physical exercises in training and rehabilitation. Dual task paradigms can induce a change in attentional focus allocation, moving focus away from a body part which is affected by fatigue. This study proposes an interface which integrates the motion tracking capabilities of a Kinect with the touch screen input data and vibration feedback of a smart phone. This interface is exploited to design and evaluate a dual task paradigm tested through an experimental study. Purpose of such paradigm is to support upper arm rehabilitation, by generating a distraction from the target area of the limb during repetitive tasks. The data collected during the experiments and the interface itself will be analyzed and discussed.

Virtual sequencing with a tactile feedback device

Since the beginning of Virtual Reality many artistic applications were developed, showing how this technology could be exploited not only from a technical point of view, but also in the field of feelings and emotions. Nowadays music is one of the most interesting field of application for Virtual Reality, and many environments provide the user with means to express her/himself; our work follows this direction, aiming at developing a set of multimodal musical interfaces. In this paper we present a first simple virtual sequencer combined with a low cost tactile feedback device: some preliminary experiments were done to analyze how skilled musicians approach this unusual way of making music.