Central perceptual task difficulty on peripheral detection performance

People cannot respond to all the stimuli which are present at any given moment. Consequently, we attend to a severely restricted selection of potential information and ignore the remainder. The process of selecting certain information, as opposed to other information impinging on the sensory receptors, has been termed selective attention (Treisman, 1969).

When persons are required to perform two or more tasks at the same time, performance on at least one of the tasks usually deteriorates from that observed when the same tasks are performed separately. The results of the investigations in this experimental area served as one of the principal sources of evidence in support of the notion that man is limited in the amount of information he can process per unit of time (Broadbent, 1958; Norman, 1968; Treisman, 1969) Since there is a type of competition between signals for some limited capacity system, tasks which place demands on the central limited capacity tend to interfere with each other (Posner & Boies, 1971). A number of investigations (e.g., Welch, 1898; Welford, 1968) have used this basic idea to measure the attention demands of one task by its interference with a secondary task.