This study aimed to review the literature describing and quantifying time lags in the health research translation process. Papers were included in the review if they quantified time lags in the development of health interventions. The study identified 23 papers. Few were comparable as different studies use different measures, of different things, at different time points. We concluded that the current state of knowledge of time lags is of limited use to those responsible for R&D and knowledge transfer who face difficulties in knowing what they should or can do to reduce time lags. This effectively ‘blindfolds’ investment decisions and risks wasting effort. The study concludes that understanding lags first requires agreeing models, definitions and measures, which can be applied in practice. A second task would be to develop a process by which to gather these data.

The Answer Is 17 Years, What Is the Question

The condition for dynamic stability

An important and troublesome problem with current virtual environment (VE) technology is the tendency for some users to exhibit symptoms that parallel symptoms of classical motion sickness both during and after the VE experience. This type of sickness, cybersickness, is distinct from motion sickness in that the user is often stationary but has a compelling sense of self motion through moving visual imagery. Unfortunately, there are many factors that can cause cybersickness and there is no foolproof method for eliminating the problem. In this paper, I discuss a number of the primary factors that contribute to the cause of cybersickness, describe three conflicting cybersickness theories that have been postulated, and discuss some possible methods for reducing cybersickness in VEs.

/pdf/a-discussion-of-cybersickness-in-virtual-environments-47jpgfr9mv.pdf

A discussion of cybersickness in virtual environments

A necessary condition for visually guided action is that an organism perceive what actions are afforded by a given environmental situation. Warren (1984) proposed that an affordance such as the climbability of a stairway is determined by the fit between properties of the environment and the organism and can be characterized by optimal points, where action is most comfortable or efficient, and critical points, where a phase transition to a new action occurs. Perceiving an affordance, then, implies perceiving the relation between the environment and the observer's own action system. The present study is an extension of this analysis to the visual guidance of walking through apertures. We videotaped large and small subjects walking through apertures of different widths to determine empirically the critical aperture-to-shoulder-width ratio (A/S) marking the transition from frontal walking to body rotation. These results were compared with perceptual judgments of "passability" under static and moving viewing conditions. Finally, we tested the hypothesis that such judgments are based on intrinsic or body-scaled information specifying aperture width as a ratio of the observer's eyeheight. We conclude (a) that the critical point in free walking occurs at A/S = 1.30, (b) that static monocular information is sufficient for judging passability, and (c) that the perception of passability under such conditions is based on body-scaled eyeheight information.

http://www.cog.brown.edu/Research/ven_lab/Publications/WarrenWhang_Aperture_JEP87.pdf

Visual guidance of walking through apertures: body-scaled information for affordances.

The use of virtual-reality technology in the areas of rehabilitation and therapy continues to grow, with encouraging results being reported for applications that address human physical, cognitive, and psychological functioning. This article presents a SWOT (Strengths, Weaknesses, Opportunities, and Threats) analysis for the field of VR rehabilitation and therapy. The SWOT analysis is a commonly employed framework in the business world for analyzing the factors that influence a company's competitive position in the marketplace with an eye to the future. However, the SWOT framework can also be usefully applied outside of the pure business domain. A quick check on the Internet will turn up SWOT analyses for urban-renewal projects, career planning, website design, youth sports programs, and evaluation of academic research centers, and it becomes obvious that it can be usefully applied to assess and guide any organized human endeavor designed to accomplish a mission. It is hoped that this structured examination of the factors relevant to the current and future status of VR rehabilitation will provide a good overview of the key issues and concerns that are relevant for understanding and advancing this vital application area.

/pdf/a-swot-analysis-of-the-field-of-virtual-reality-3q1uid6pyq.pdf

A SWOT analysis of the field of virtual reality rehabilitation and therapy

In this article we present a new theory of motion sickness. In the sensory conflict theory, changes in stimulation of perceptual systems are believed to be responsible for motion sickness. We discuss the fact that these changes in stimulation are not independent of the animal-environment interaction, but are determined by corresponding changes in the constraints operating on the control of action. Thus, provocative situations may be characterized by novel demands on the control of action as well as by novel patterns of stimulation. Our hypothesis is that animals become sick in situations in which they do not possess (or have not yet learned) strategies that are effective for the maintenance of postural stability. We identify a broad range of situations over which the occurrence of motion sickness is related to factors that should influence postural stability. This allows us to establish a logical link between motion sickness and postural stability. Our analysis implies that an understanding of stability s...

An ecological Theory of Motion Sickness and Postural Instability

Visually induced motion sickness is a syndrome that occasionally occurs when physically stationary individuals view compelling visual representations of self-motion It may also occur when detectable lags are present between head movements and recomputation and presentation of the visual display in helmet-mounted displays The occurrence of this malady is a critical issue for the future development and implementation of virtual environments Applications of this emerging technology are likely to be compromised to the extent that users experience illness and/or incapacitation This article presents an overview of what is currently known regarding the relationship between visually specified self-motion in the absence of inertial displacement and resulting illness and perceptual-motor disturbances

Visually induced motion sickness in virtual environments

Affordances as constraints on the control of stance

In this article we provide evidence against a fundamental assumption of traditional theories of orientation--that gravitoinertial force is perceived. We argue that orientation is based on information that is available in patterns of motion of the organism. We further argue that perception and control of orientation depend not only on information about an organism's motions relative to the local force environment but also on information about the surface of support and about the compensatory actions of the organism. We describe these kinds of information and discuss their availability to, and across, different perceptual systems. The use of this information for the control of orientation is emphasized. We conclude with recommendations for research based on the new approach. How do organisms orient themselves in the environment? To what do they orient? The answer to these questions has seemed so obvious for so long that it is taken for granted: Organisms orient to gravity. They sit, stand, walk, run, throw, catch, dance, and do gymnastics relative to the omnipresent force of gravity. "Gravity is probably the most important spatial reference cue for an organism" (Schone, 1984, p. 258). Within this context, what are the functions of the perceptual systems? How do the perceptual systems contribute to the achievement and maintenance of orientation in terrestrial environments and in such situations as flight and weightlessness? In this article we analyze the information for orientation that is available to the perceptual systems. Our analysis leads us to two important areas of disagreement with the classical approach to spatial orientation. One is in the nature of the information for orientation; this is discussed in the first half of the article. The other concerns cooperation between perceptual systems in the perception and control of orientation and is dis

Gary E. Riccio

Papers

An ecological Theory of Motion Sickness and Postural Instability

Visually induced motion sickness in virtual environments

Affordances as constraints on the control of stance

An ecological theory of orientation and the vestibular system.

Information in movement variability about the qualitative dynamics of posture and orientation