Sustained Attention

While selective attention is mainly concerned with choosing among stimuli, sustained attention is concerned instead with concentration -- our ability to maintain attention on a particular object or event for a long stretch of time. It is also known as vigilance. In certain occupations, people are required to concentrate on a specific task for many hours at a stretch -- air traffic controllers and radar operators are good real-world examples, since they must constantly watch and monitor signals appearing on screens. Because such signals typically occur unpredictably, and because errors in detecting them can have serious, even fatal, consequences, tasks of this kind demand a very high level of vigilance.

Several factors have been found to facilitate or inhibit how well a person performs on tasks that call for sustained attention. Sensory modality is one such factor: performance tends to be better when the signals being monitored are auditory rather than visual. Clarity of the stimuli is a second factor: intense, long-lasting stimuli facilitate sustained attention and lead to better performance than brief or indistinct ones. Temporal uncertainty is a third factor: stimuli that appear at regular intervals of time are attended to better than stimuli that appear at irregular intervals. Spatial uncertainty is a fourth factor: stimuli that appear at a fixed, predictable location are more readily attended to than stimuli that appear at random, unpredictable locations.

Attention has a number of practical applications in everyday life. The number of objects a person can readily attend to in a single glance -- the well-known "span of attention" or "perceptual span", generally found to fall within seven plus or minus two items, popularly known as the "magic number" -- is used, for example, in the design of number plates for motorbikes and cars: keeping the combination of digits and letters within this range allows a traffic police officer to notice and correctly note down the details of a vehicle at a single glance in case of a rule violation. …