Measurement of Control Skills, Vigilance, and Performance on a Subsidiary Task during 12 Hours of Car Driving

Abstract

Eight subjects were given short driving tests at 0700, 1000, 1300, 1400. 1700 and 2000 hours on 2 days: (1) under experimental conditions of continuous driving and (2) under control conditions in which they carried on with their normal work between tests. Car control skills and performance on a subsidiary task of time-interval production were measured on a 2·2 mile test circuit in city traffic. Pulse rate and oral temperature were also recorded. Vigilance was measured during main-road driving on the experimental day by scoring time taken to respond to a light signal. Vigilance improved significantly during the spell of prolonged driving. Time-interval production was reliably more variable under experimental conditions than under control, but this difference was independent of the duration of the driving period. Differences in car-control skills between conditions were slight and statistically unreliable. These results support previous findings that a virtually continuous 12 hour period of driving during the normal working day need not affect either perceptual or motor skills adversely.

The apparent discrepancy between present findings, that performance on the subsidiary task was worse on the day of prolonged driving, and previous findings, that it tended to be better, is briefly discussed in relation to the general problem of measuring performance by the dual-task method.