The efficacy of some auditory–vocal subsidiary tasks as measures of the mental load on male and female drivers

Eight male and eight female drivers took part in a study to assess the efficacy of a number of auditory–vocal subsidiary tasks as measures of the mental load imposed by driving under standardized conditions. Performing the subsidiary tasks appeared to interfere with female driving ability, but not with that of males. Some differences in subsidiary task performance were found between driving and non-driving conditions for both males and females. However, no one task appeared outstanding as a measure of mental load, and the performance decrements may have been due as much to auditory masking by the car noise as to competition for information-processing resources. The validity of dual-task methods is discussed, and it is argued that the use of common sensory or response modes cannot be avoided, but may in some cases be used to advantage.