Using a virtual reality system to study balance and walking in a virtual outdoor environment: a pilot study.

Falls and fall-related injuries are a major problem for elderly persons. Most falls occur during walking and turning, and the risk of falling increases when attention is diverted to something besides walking. It is often difficult to standardize methods for testing balance and fall tendency in a clinically relevant setting. We describe the development of a system using a virtual environment (VE) to assess how attention demanding and unexpected events influence a person's capacity to control balance and movement. The hardware in the system consists of a head-mounted display (HMD), a magnetic tracker system, and two SGI computers. The software consists of the image generation of the VE and the management and visualization of motion tracking data. In a preliminary pilot study eight subjects (age 23-80) participated. Each subject walked on a normal floor and was visually presented a familiar outdoor environment in the HMD. They were exposed to different unexpected events, such as a virtual snowfall and tilting of the VE. Disturbances of balance and walking patterns such as changes in speed, stride length and balance reactions like slipping were observed. Two subjects experienced symptoms of cyber sickness with a SSQ score above 25 points. Walking with sensors only did not affect walking time, but in VE the subjects generally walked more slowly. Virtual tilting of the environment had an impact on balance performance during walking. This effect was not observed while the test subjects were walking in a virtual snowfall. The model needs further development but may hold a potential for clinical use.     

Testing for the presence of 1/f noise in continuation tapping data.

A number of recent papers have suggested that the series of time intervals produced in continuation tapping may have fractal properties. This proposition, nevertheless, was only based on the visual appraisal of graphical results, and was not statistically supported. In the present study, we applied the ARMA/ARFIMA modeling procedures proposed by Wagenmakers, Farrell, and Ratcliff (2005) to test for the presence of long-range dependencies in continuation tapping data. Our results demonstrate the presence of long-range dependencies in most series and offer strong support for the hypothesis that fluctuations in tapping series are fractal in nature.     

Normative Publication Productivity of Communication Scholars at Selected Career Milestones

This study builds on past research on normative publication practices in the communication discipline by exploring rates of contribution to the discipline’s literature as represented in the Communication Institute for Online Scholarship’s ComAbstracts database. The ComAbstracts database, spanning 90 years and more than 46,000 publications, provides significantly greater breadth and depth than previously available data sources. The strategy for sampling scholars included in this study also differs from prior work by limiting the sample to scholars affiliated with the communication field through membership in one of its primary professional societies. For purposes of studying historical change in productivity, the sample of scholars was divided into six cohorts at different points in their careers to discover norms for publication productivity at milestone intervals following career onset, defined as the date of award of the Ph.D. or an equivalent terminal degree. Among other findings, results suggest (a) that rates of contribution of single‐authored articles have fallen significantly over the years without compensating increases in the number of multiauthored publications, (b) that an early high rate of publication productivity is highly predictive of a sustained high rate, and (c) that more than one third of the membership of the scholars sample had not contributed any articles to the field’s mainline periodical literature. As well, a metric for determining exceptionally high and low productivity rates by career stage is suggested and illustrated, revealing a way of identifying top‐tier and subnormal productivity adjusted for years in career.     

The association of depression and sense of belonging with suicidal ideation among older adults: applicability of resiliency models

Suicide among older people, especially men, is a significant problem. In this study the applicability of the compensatory, the risk-protective, the challenge, and the protective-protective models of resiliency for the prediction of suicidal ideation from depression (the risk factor) and sense of belonging to the community (the protective factor) was investigated. A total of 351 retired Australians (130 males and 221 females), with a mean age of 71.31 years (SD = 7.99), completed the Zung Depression Scale, the suicide subscale of the General Health Questionnaire, and the Sense of Belonging Instrument. When sense of belonging (psychological) was the protective factor, results indicated support for the risk-protective model for men and women, and for the compensatory model for women only. In contrast, when sense of belonging (antecedents) was the protective factor, support was evident for the compensatory model for men and women, and for the challenge model for women only. Results indicate that interventions should be developed to enhance sense of belonging among aging adults.     

Radical Innovation and End-User Involvement: The Ambilight Case

To make technology research more effective and to deal with fierce cost competition, technology research should be more focused on radical innovation and needs to adopt a more end-user-focused approach. Product improvement is already quite often building on knowledge collected around consumers’ experiences with these products to come with a next, improved generation of products. However, in case of creating novel products from “scratch,” this will be more difficult. The user-centered research approach including insights, scenarios, and experience prototypes provides a good method to incorporate the consumer perspective in the earliest stages of the product creation process. The development of the Ambilight TV will be used as a case to illustrate this approach.     

The relation between worrying and concerns: the importance of perceived probability and cost

The relation between worrying and individuals' concerns was examined in a sample of 197 college students. Participants described the five undesirable outcomes that they thought about most often, indicated how likely they thought the outcomes were, and how upset they would be by them. Worry severity was measured using the Penn State Worry Questionnaire. The relation between worry severity and the life domains about which individuals were concerned was quite weak. In contrast, as predicted, greater worry was associated with higher probability and cost estimates. In addition, cost estimates moderated the relation between worry severity and probability estimates. The potential importance of perceived threat for understanding worrying is discussed.     

Exploiting redundancy for flexible behavior: unsupervised learning in a modular sensorimotor control architecture

Autonomously developing organisms face several challenges when learning reaching movements. First, motor control is learned unsupervised or self-supervised. Second, knowledge of sensorimotor contingencies is acquired in contexts in which action consequences unfold in time. Third, motor redundancies must be resolved. To solve all 3 of these problems, the authors propose a sensorimotor, unsupervised, redundancy-resolving control architecture (SURE_REACH), based on the ideomotor principle. Given a 3-degrees-of-freedom arm in a 2-dimensional environment, SURE_REACH encodes 2 spatial arm representations with neural population codes: a hand end-point coordinate space and an angular arm posture space. A posture memory solves the inverse kinematics problem by associating hand end-point neurons with neurons in posture space. An inverse sensorimotor model associates posture neurons with each other action-dependently. Together, population encoding, redundant posture memory, and the inverse sensorimotor model enable SURE_REACH to learn and represent sensorimotor grounded distance measures and to use dynamic programming to reach goals efficiently. The architecture not only solves the redundancy problem but also increases goal reaching flexibility, accounting for additional task constraints or realizing obstacle avoidance. While the spatial population codes resemble neurophysiological structures, the simulations confirm the flexibility and plausibility of the model by mimicking previously published data in arm-reaching tasks.