Analysis of compensative behavior in demanding driving situations

Drivers usually perform a range of different activities while driving. Following a classical workload approach, additional activities are expected to increase the demand on the driver. Nevertheless, drivers can usually manage even demanding situations successfully. They seem to be able to compensate demands by behavior adaptations, mainly in the following factors: in the driving task itself, in an additional (secondary) task and in their mental workload. It is suggested that by analyzing these three factors in temporal coherence, compensative interactions between them become measurable. Additionally, a reduction of activity in the secondary task is expected to be influenced by the characteristics of this task. To analyze these effects, a driving simulator study with 33 participants was accomplished. It could be shown that if a secondary task can be interrupted without a perceived decline in performance, it is interrupted in demanding driving situations. If an interruption causes a perceived performance loss, efforts are increased, and so the workload is heightened (measured with a high resolution physiological measurement based on pupillometry). Thus, drivers compensate their current demands by behavior adaptations in different factors, depending on the characteristics of a secondary task.