Unimanual and Bimanual Weight Perception of Virtual Objects with a new Multi-finger Haptic Interface

Accurate weight perception is important particularly in tasks where the user has to apply vertical forces to ensure safe landing of a fragile object or precise penetration of a surface with a probe. Moreover, depending on physical properties of objects such as weight and size we may switch between unimanual and bimanual manipulation during a task. Research has shown that bimanual manipulation of real objects results in a misperception of their weight: they tend to feel lighter than similarly heavy objects which are handled with one hand only [8]. Effective simulation of bimanual manipulation with desktop haptic interfaces should be able to replicate this effect of bimanual manipulation on weight perception. Here, we present the MasterFinger-2, a new multi-finger haptic interface allowing bimanual manipulation of virtual objects with precision grip and we conduct weight discrimination experiments to evaluate its capacity to simulate unimanual and bimanual weight. We found that the bimanual ‘lighter’ bias is also observed with the MasterFinger-2 but the sensitivity to changes of virtual weights deteriorated

Using cloud technologies for engaging people with cultural heritage

Cultural heritage is an important asset of Europe which is largely underexplored. One of the main reasons is that the general public do not really incorporate cultural activities in their life style. Currently, curators and professionals in the heritage sector face the toughest challenges on how to attract, engage and retain visitors of heritage institutions (libraries, museums, archives and historical societies). TAG CLOUD FP7 European project seeks to overcome this situation and promote lifelong engagement with culture by personalising the visitors? cultural experiences through cloud technologies

Design and Development of a Multimodal Vest for Virtual Immersion and Guidance

This paper is focused on the development of a haptic vest to enhance immersion and realism in virtual environments, through vibrotactile feedback. The first steps to achieve touch-based communication are presented in order to set an actuation method based on vibration motors. Resulting vibrotactile patterns helping users to move inside virtual reality (VR). The research investigates human torso resolution and perception of vibration patterns, evaluating different kind of actuators at different locations on the vest. Finally, determining an appropriate distribution of vibration patterns allowed the generation of sensations that, for instance, help to guide in a mixed or virtual reality environment

Coarse-grained information dominates fine-grained information in judgments of time-to-contact from retinal flow

AbstractTo investigate the relative importance of fine- and coarse-grained structure in the analysis of retinal flow, subjects made estimates of time-to-contact from random dot kinematograms depicting movement towards a flat, sparsely textured surface. Individual display elements moved smoothly away from each other while expanding smoothly in size. By artificially manipulating the rate at which the individual elements expanded we showed that this cue has only a small effect upon performance. When individual elements were replaced by small clusters of dots, expansion of the clusters had a similarly small effect upon performance. However, estimates of time-to-contact were possible when a single expanding cluster was presented in isolation. We conclude that both types of information are available to the subject but that estimates of time-to-contact are based primarily on coarse-grained changes in the position of image elements and that fine-grained changes in element size or position play only a minor role

Immersive Multimodal Interactive Presence

XIV, 258 p.online resource

The role of spatial integration in the perception of surface orientation with active touch

Vision research has shown that perception of line orientation, in the fovea area, improves with line length (Westheimer &amp; Ley, 1997). This suggests that the visual system may use spatial integration to improve perception of orientation. In the present experiments, we investigated the role of spatial integration in the perception of surface orientation using kinesthetic and proprioceptive information from shoulder and elbow. With their left index fingers, participants actively explored virtual slanted surfaces of different lengths and orientations, and were asked to reproduce an orientation or discriminate between two orientations. Results showed that reproduction errors and discrimination thresholds improve with surface length. This suggests that the proprioceptive shoulder-elbow system may integrate redundant spatial information resulting from extended arm movements to improve orientation judgments.</p

Analyzing hospital length of stay mean or median regression?

BACKGROUND. Length of stay (LOS) is an important measure of hospital activity and health care utilization, but its empirical distribution is often positively skewed. OBJECTIVE. This study reviews the mean and median regression approaches for analyzing LOS, which have implications for service planning, resource allocation, and bed utilization. METHODS. The two approaches are applied to analyze hospital discharge data on cesarean delivery. Both models adjust for patient and health-related characteristics, and for the dependency of LOS outcomes nested within hospitals. The estimation methods are also compared in a simulation study. RESULTS. For the empirical application, the mean regression results are somewhat sensilive to the magnitude of trimming chosen. The identified factors from median regression, namely number of diagnoses, number of procedures, and payment classification, are robust to high-LOS outliers. The simulation experiment shows that median regression can outperform mean regression even when the response variable is moderately positively skewed. CONCLUSION. Median regression appears to be a suitable alternative to analyze the clustered and positively skewed LOS, without transforming and trimming the data arbitrarily. © 2003 Lippincott Williams & Wilkins, Inc.link_to_subscribed_fulltex