In-vehicle systems may distract or interrupt the driver and can compete with the primary task of safe vehicle control. This study investigates the consequences arising from multiple in-vehicle distractions. It aims to investigate the impact of simultaneous information conflicts, from multiple secondary in-vehicle tasks, on the primary task of driving.</p> <p>Participants were presented with a primary task, representing some of the visual and manual aspects of driving, and three secondary tasks (visual, auditory, and visual and auditory stimuli), representing some of the aspects of in-vehicle system operation. Differences between the impact of the three secondary tasks on performance in the primary task were investigated. The priority (high/low) that participants applied to the task was also considered.</p> <p>Lane exceedence (vehicle out of lane) and lane deviation (tracking error) were found to increase with the introduction of secondary tasks. Overall mental workload and anger and frustration were reported as being higher when conducting both primary and secondary tasks, as opposed to solely a primary task. Differences between the impact of the three secondary tasks on these factors were not observed. Findings suggest that in situations of information conflict, participants experience equal task disruption regardless of the sensory channel of the secondary task if the quantity of information presented is carefully controlled. Resource theories would suggest that overloading the visual channel would result in performance decrements. Findings from this study do not support this view. Copyright © 2002 TRL Limited.