The effects of objective workload on cognitive performance in a field setting: A two‐period cross‐over trial

In this field study, the work schedules of Driving Test Examiners1were systematically manipulated in a two‐period cross‐over trial designed to evaluate the effects of workload reduction (from the normal level of nine Driving Tests per day to either eight or seven Tests per day) on alertness. The research formed part of a wider study undertaken at the request of the Department of Transport to determine whether workload reduction should be introduced on a national basis to enhance working effectiveness and well‐being in this occupational group. Search‐and‐memory (SAM) tasks (with three levels of memory load) were administered at the start, middle, and end of the workday on pre‐determined days in each experimental period. Data analysis (n=49) showed that, with accuracy statistically controlled, speed of search improved more rapidly during the morning work period under reduced workload conditions (four Tests) than under normal workload (five Tests). This difference was maintained during the afternoon but did not increase. The effects of the seven Tests schedule were not found to be markedly different from those of the eight Tests schedule. The findings and recommendations are discussed with reference to relevant literature. Copyright © 1995 John Wiley & Sons, Ltd