Subsidiary-Task Assessment of Age Differences in Attentional Capacity During Real-World and Simulated Driving

Advances in ITS in-vehicle technologies promise to impose new information-processing demands upon drivers. Potential information “overload” problems may become especially acute among older drivers -the fastest growing segment of the driving population. In this investigation, the efficacy of a subsidiary task technique for detecting and quantifying age-differences in the attentional demands of driving-related tasks was evaluated. Young (mean age = 19.6) and old (mean age = 71.3) licensed drivers participated in a simulated driving task while simultaneously performing a series of simple mental arithmetic computations. Response latencies on the mental arithmetic task slowed significantly for the old – but not young – drivers as the primary task of driving was made more difficult. Identical results were obtained when the study was repeated under real-world – rather than simulated – driving conditions. These findings suggest that subsidiary task techniques are sufficiently sensitive tools for detecting and quantifying age-related “shortfalls” in the attentional resources needed to safely and effectively operate a motor vehicle. These techniques may play an important role in assuring that older drivers are not “designed out” of next-generation transportation systems.