Human Factors and User Studies

Human factors in Virtual Reality

This article discusses human factors issues surrounding virtual reality and how these might be addressed. One of the main problems with virtual reality is motion sickness brought on by poor design or ergonomics which affects people in different ways.

This motion sickness occurs when the person views an interactive display but their head remains still at all times. Many VR systems use a tracking device which records head movements made by the person and adjusts the images accordingly.

Cybersickness

But any disruption to these causes disorientation, dizziness and feelings of nausea which are known as cybersickness. This condition affects everyone differently with some people only experiencing this after a several hours whereas others are affected within a few minutes.

A time lag or latency is one of a couple of reasons for this sensation. Another is the equipment used such as a head mounted display (HMD) and lenses which cause affect the balance as well as causing tiredness. This is a particular feature of CAVE fully immersive systems also leads to cybersickness.

Usability of virtual reality systems

User studies need to be carried out to determine the exact cause of this condition and ways of dealing with the symptoms. This is important as there needs to be guidelines in place regarding the safe use of virtual reality systems and things to be aware of when doing so.

But there are principles which can be assessed with virtual reality that are used in standard usability testing. These include:

  • Performance, e.g. task effectiveness
  • Satisfaction
  • Error rate
  • Error tolerance
  • Utility

Observation and questionnaires have been used which are standard usability techniques for a range of interactive systems. But there are noticeable differences between VR and other types of user interfaces.

One response is to conduct testing with users in which they are given a set of tasks to perform within different virtual reality set ups, e.g. non-immersive and fully immersive. The data is recorded and interviews conducted following a period of observation.

The aim is to determine if user performance is boosted by use of virtual reality: is the equipment suitable for their needs and does the choice of input device, e.g. glove, joystick etc, have a bearing on the outcome.

Further research is needed to determine the usability or otherwise of virtual reality systems.

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