Attention: Vigilance (VIG) Module

Setting and Task

The subject is presented with a situation in which he appears to be driving along a straight highway. At irregular intervals other vehicles come towards him on the opposite carriageway or overtake him. The subject's task is to react by pressing a button when an overtaking vehicle suddenly brakes in front of him. Once he has reacted the vehicle's brake lights go out and it accelerates away from him. If the subject fails to react within the permitted time, the brake lights start to flash. Eventually there is a loud squeaking noise, which is designed to draw the subject's attention to what is happening.

Theory

Long-term alertness tasks require the subject's attention to be focused continuously for long periods of time on one or more sources of information, in order to detect and respond to small changes in the information presented (Davies et al. 1984). Vigilance represents a special variant of attention. Vigilance makes demands on attention over a long period of time - often a number of hours - and the relevant stimuli typically occur at very irregular intervals and at a very low frequency compared to the number of irrelevant stimuli. Vigilance training cannot be effective unless a training session lasts for more than 30 minutes at the minimum.

Difficulty Structure

The VIG training program has 30 difficulty levels. A decreasing stimulus frequency makes it more and more difficult for the subject to sustain his attention: he is overtaken by other cars increasingly rarely, the surroundings become more monotonous as darkness falls and the number of sudden braking maneuvers from overtaking vehicles decreases. In addition, the intensity of the feedback on delayed and omitted reactions becomes weaker as the difficulty level increases. The challenge therefore changes gradually from a sustained attention task to one requiring real vigilance. At each difficulty level the maximum permitted reaction time adapts to the speed of the subject's reactions. Taking the subject's first valid reactions as a starting point, an individual reaction time limit is determined and used as a basis for measuring all further reactions made in the course of the training program. This ensures that from the outset the training program is optimally adapted to the client's ability and is neither too easy nor too difficult for him.

Note

The VIG training program can also be used with patients with impairments of the visual field. The instructions are then displayed on only one side of the screen.