Virtual reality is set to be the next ‘disruptive technology’, changing the way we live, work and play. The technology is commonly portrayed as the new kid on the block, following hard on the heels of smartphones and the internet. But virtual reality has been in existence for decades and its impact has been thwarted in the past because of potential health and safety issues.

It’s said that those who don’t learn from history are condemned to repeat it. So, it’s worth taking a look at why concerns have previously been raised about this technology and how this might impact on the technological revolution taking place today.

The health impact of virtual reality

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.

University of Leeds Driving Simulator

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 challenge for virtual reality

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).

The physical links between focus and eye direction are reflected in the organisation of the brain so that the system responsible for focus is linked with the system that controls eye direction. In scientific jargon, the systems are said to be ‘neurally cross-linked’. It’s probable that these neural cross-links evolved as a mechanism for minimising surprise when one or other system altered to look towards an object located at a different distance.

The problem with existing virtual environments is that the computer generated images are shown on two dimensional screens, meaning that the eyes must stay focused in one location. However, the presentation of three dimensional binocular images forces the eyes to change direction as if they were gazing at a near or far object. This mismatch between the focusing and eye alignment systems creates surprise, and this places pressure on the human visual system to adapt to minimise this surprise.

It’s known that these short-term adaptation pressures can cause headaches and sore eyes in users and potentially make it harder for someone to concentrate on a visual task (such as reading a book). The long term consequences are simply unknown.

The future of virtual reality

It may turn out that the human brain can adapt to these unnatural pressures without any long term problems. But it’s also possible that these pressures may cause long term difficulties. These issues are of particular concern in young children who may be more susceptible to disruptive pressures owing to their developing brains.

These problems were first identified over two decades ago but a suitable solution is still to be found. One simple fix is to avoid presenting three dimensional binocular images and this may be sensible in some settings. But our own research has shown that more creative projects and a number of tasks — including surgery — require these three dimensional projections.

This means that innovative solutions need to be found to this problem and all aspects of how we interact with virtual reality displays. Finding solutions that crack these problems will revolutionise human-computer interaction and help realise the massive potential of virtual reality to usher in an era where the problems associated with traditional computer interaction — such as neck and back pain — become relegated to medical history.