More and more in-vehicle systems are rapidly becoming commercially available, making the driving task more and more complex. Driving performance in such multiple-task situations depends primarily on the level of task demands imposed on the driver by certain situations. The higher the perceived task difficulty, the higher the workload level of that individual. The aim of this dissertation was therefore to investigate possible trade-offs between primary task and secondary task performance in a simulated driving environment. For this purpose, the effects (...) of a standardized secondary visual search task on the primary task of driving were evaluated and compared between several conditions. Even though there was a clear tendency to protect the primary task of driving, participants seemed incapable of fully prioritising the primary task of driving over the secondary search task at all times. (shrink)