NDOGENOUS MENTAL LOAD AND DISTRACTION IN EVERYDAY DRIVING
 
Nunes, L.M., Direccin General de Trfico and Recarte, M.A., Universidad Complutense de Madrid, Spain
 
Distraction is a highly relevant factor in accident causation and there is a general concern about the efficacy and risks of information systems on the road or in the vehicles. While the ergonomic perspective stresses the relevance of environmental factors, the potential distractor of our spontaneous everyday thoughts while driving has been scarcely studied. In the recent years we conducted several on the road experiments to study the effects of non-environmental factors. The first findings demonstrated that different mental tasks foreign to driving produced changes in visual search patterns: spatial gaze concentration, long ocular fixations for spatial imagery tasks and lower mirrors and speedometer inspection. Further research extended the study to a wide variety of cognitive tasks, including a hands free phone conversation. In this research, the previously cited visual search changes were reproduced and the implications of mental activity for road safety were analysed in terms of detection and decision- making capacities and speed control as well. The results suggest that under increased mental load, drivers tend to spare visual resources by reducing glances to irrelevant objects. Despite of this the net balance between effort and demands is negative: mental activity can lead to distraction: visual processing capacities and driving performance proved to be negatively affected.