Driving without awareness

A phenomenon which is sometimes confused with driver fatigue, but is quite different is driving without awareness (DWA). Drivers may demonstrate low attention levels during driving without being fatigued by time on task, lack of sleep, bad sleep or time of day. The driver performs in a state in which he has no active attention for the driving task and performs on 'autopilot'. At a certain moment the driver 'awakes' and he or she cannot remember the foregoing drive period. This phenomenon has been labelled as 'Driving without awareness' and also as 'Highway hypnosis' or 'Driving without attention mode' (DWAM). Brown [15] links this phenomenon to the monotony of the driving task or situations that presents the same and predictable visual task demand. During DWA the eyes stay open in contrast to micro-sleep during which the eyes are closed for at least 2 seconds. In Box 2, research on driving without awareness is described.

Karrer et al [57] let a representative sample of 83 German drivers perform for 2 hours on a monotonous driving task on motorway. Trained observers registered the occurrence of DWA, as being indicated by one or more of the following symptoms:

The driver began to stare into space
The drivers began to stare and head shakes upwards or downwards
Start of rolling eye movement of the driver
Start of squinting.

During the drive, the EEG (duration and frequency alpha waves), eye jumps (saccades) and the frequency of eye blinks were measured. Also, traffic errors were measured (mainly crossing over edge markings). DWA occurred for 18% of the drivers, and relatively more for young male drivers. The 83 participants in total crossed 260 times edge marking. In 33, 5% of these cases, DWA was present. DWA went together with a decrease in the number of eye jumps and a decrease in the size of the jumps. The higher the frequency of DWA moments, the longer the duration of eye blinks. This last results supports the conclusion that DWA occurs at a low intensity attention level and that this causes more traffic errors to be made.