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 task, suggesting that periodical sampling results from an imperfect internal representation and is not the result of a strategic decision of the observer to overcome overload.