Monday, September 18, 2017

Virtual Reality Health Risks...,

medium |  Two decades ago, our research group made international headlines when we published research showing that virtual reality systems could damage people’s health.

Our demonstration of side-effects was not unique — many research groups were showing that it could cause health problems. The reason that our work was newsworthy was because we showed that there were fundamental problems that needed to be tackled when designing virtual reality systems — and these problems needed engineering solutions that were tailored for the human user.

In other words, it was not enough to keep producing ever faster computers and higher definition displays — a fundamental change in the way systems were designed was required.

So why do virtual reality systems need a new approach? The answer to this question lies in the very definition of how virtual reality differs from how we traditionally use a computer.

Natural human behaviour is based on responses elicited by information detected by a person’s sensory systems. For example, rays of light bouncing off a shiny red apple can indicate that there’s a good source of food hanging on a tree.

A person can then use the information to guide their hand movements and pick the apple from the tree. This use of ‘perception’ to guide ‘motor’ actions defines a feedback loop that underpins all of human behaviour. The goal of virtual reality systems is to mimic the information that humans normally use to guide their actions, so that humans can interact with computer generated objects in a natural way.

The problems come when the normal relationship between the perceptual information and the corresponding action is disrupted. One way of thinking about such disruption is that a mismatch between perception and action causes ‘surprise’. It turns out that surprise is really important for human learning and the human brain appears to be engineered to minimise surprise.

This means that the challenge for the designers of virtual reality is that they must create systems that minimise the surprise experienced by the user when using computer generated information to control their actions.

Of course, one of the advantages of virtual reality is that the computer can create new and wonderful worlds. For example, a completely novel fruit — perhaps an elppa — could be shown hanging from a virtual tree. The elppa might have a completely different texture and appearance to any other previously encountered fruit — but it’s important that the information used to specify the location and size of the elppa allows the virtual reality user to guide their hand to the virtual object in a normal way.

If there is a mismatch between the visual information and the hand movements then ‘surprise’ will result, and the human brain will need to adapt if future interactions between vision and action are to maintain their accuracy. The issue is that the process of adaptation may cause difficulties — and these difficulties might be particularly problematic for children as their brains are not fully developed. 

This issue affects all forms of information presented within a virtual world (so hearing and touch as well as vision), and all of the different motor systems (so postural control as well as arm movement systems). One good example of the problems that can arise can be seen through the way our eyes react to movement.

In 1993, we showed that virtual reality systems had a fundamental design flaw when they attempted to show three dimensional visual information. This is because the systems produce a mismatch between where the eyes need to focus and where the eyes need to point. In everyday life, if we change our focus from something close to something far away our eyes will need to change focus and alter where they are pointing.

The change in focus is necessary to prevent blur and the change in eye direction is necessary to stop double images. In reality, the changes in focus and direction are physically linked (a change in fixation distance causes change in the images and where the images fall at the back of the eyes).