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Thursday, March 10, 2011

Helmets can cause accidents.........

OFF THE WIRE
Sent by Don
Posted in 1995 at http://www.usff.com/hldl/hoax/simsickness.html

As the battles continue in the legislatures of the various states to eliminate mandatory helmet laws, the issue of "safety" becomes more and more a debatable subject. In an effort to help arm those who are attacking on this front, we present the following excerpt from an article published in a magazine called Virtual Reality World, in which the discussion turns to elements of helmet use resulting from the unnatural weight on the head and neck, particularly as it impacts 100 million years of evolutionary conditioning.
Although the article is directed toward the problems associated with virtual reality machines, and the head equipment used to produce virtual reality; the observations concerning the distraction caused by "tricking" mother nature by adding weight to the head, easily cross over to the helmet use safety issue. When the undetected impact of the unnatural weight a helmet may cause is applied to the mandatory use of helmets, the result is at least one more argument against mandatory helmet use laws -- one more un-safety argument. (As was recently discovered in California, these "unsafe" arguments do not work to support modification of existing laws, but will absolutly support any repeal bill your state may be considering.)

Here is the relevant portion of the article as we found it:
Movement and Motion Sickness
Humans (indeed all mammals) incorporate exceedingly complex feedback mechanisms involving vision, touch, vestibular sensation, proprioception (bodily position) and somato-sensation (pressure on skin). These integrated mechanisms have evolved across perhaps a hundred million years in order to enable walking, running, fighting, capturing food, as well as sex, racquetball and the operation of video games.
One may view this perceptual system as a highly redundant way of determining the state of the body in the world and of enabling the planning of actions. When cues are inconsistent, the organism must adapt and make its best estimate of the true state of affairs. This integrated system is not at all well understood, but a number of properties have been established.
Among the generally accepted facts are these:
* Visual simulators (e.g. flight simulators), both with and without motion bases, often cause symptoms indistinguishable from motion sickness and space sickness. Here, we will refer to the phenomenon as sim-sickness.
* Sim-sickness has many manifestations besides emesis (nausea and vomiting), including fatigue, generally lowered performance, and headache. The subject may not be consciously aware that his or her performance has been degraded.
* Simply adding a weight to a person's head can induce motion sickness, because of the altered feedback loops involving muscle action and head motion.
* Delays in visual feedback due to tracker latency, vehicle dynamics, models and visual system delays are a well-known source of sim-sickness.
* Some people don't experience problems, some do. Some adapt readily, some not at all.
* No general theory exists to predict what combinations of inputs and outputs will be disruptive, easy or hard to adapt to, or who will be must likely to feel the effects.
Two "layers" of causes for sim-sickness can be described: a primary layer that is essentially due to the failings of today's technology, and a second layer that is inherent to the process of simulation.
We can anticipate that improving technology will eliminate most of the primary effects, for example by speeding the operation of trackers and visual systems. The inherent effects include the impossibility of providing sustained accelerations which are fully consistent with, say, a simulated aircraft flight -- short of putting the simulator in an airplane or spacecraft!



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