Driving simulators allow researchers to study driver training issues and driver behavior under conditions in which it would be illegal and/or unethical to place drivers. For instance, studies of driver distraction would be dangerous and unethical (because of the inability to obtain informed consent from other drivers) to do on the road. With the increasing use of various in-vehicle information systems (IVIS) such as satellite navigation systems, cell phones, DVD players and e-mail systems, simulators are playing an important rule in assessing the safety and utility of such devices. Fidelity There exists a number of types research driving simulators, with a wide range of capabilities. The most complex, like the National Advanced Driving Simulator, have a full-sized vehicle body, with six-axis movement and 360-degree visual displays. On the other end of the range are simple desktop simulators that are often implemented using a computer monitor for the visual display and a videogame-type steering wheel and pedal input devices. These low cost simulators are used readily in the evaluation of basic and clinically oriented scientific questions. The issue is complicated by political and economic factors, as facilities with low-fidelity simulators claim their systems are "good enough" for the job, while the high-fidelity simulator groups insist that their (considerably more expensive) systems are necessary. Research into motion fidelity indicates that, while some motion is necessary in a research driving simulator, it does not need to have enough range to match real-world forces. Recent research has also considered the use of the real-time photo-realistic video content that reacts dynamically to driver behaviour in the environment. Validity There is a question of validity—whether results obtained in the simulator are applicable to real-world driving. One review of research studies found that driver behavior on a driving simulator approximates (relative validity) but does not exactly replicate (absolute validity) on-road driving behavior. Another study found absolute validity for the types and number of driver errors committed on a simulator and on the road. Yet another study found that drivers who reported impaired performance on a low fidelity driving simulator were significantly more likely to take part in an accident in which the driver was at least partially at fault, within five years after the simulator session. Some research teams are using automated vehicles to recreate simulator studies on a test track, enabling a more direct comparison between the simulator study and the real world. As computers have