The effect of secondary task load on visual sampling behaviour.

This paper investigates a dual-task experiment, which looked at whether periodical sampling (Senders 1983) of relatively fast changing instruments results from an imperfect internal representation of these instruments, or whether it merely represents a strategy adopted by the observer to overcome overload situations. Subjects either monitored a fast or a slow instrument in combination with a difficult, easy or no tracking task. The results indicated that sampling behaviour was generally unaffected by the external load imposed by the tracking representation and is not the result of a strategic decision of the observer to overcome overload.