Relating the Detection Response Task to Critical Events – Consequences of high Cognitive Workload to Brake Reaction Times

Abstract Currently the use of new interaction modalities with in-vehicle information systems (IVIS), for example speech interaction, leads to a shift from visual-manual workload to more cognitive workload. The aim of this study was to better determine the link between increasing cognitive workload and corresponding reaction times that are relevant to the driving task, for example brake reactions to sudden events. In a driving simulator study with 35 middle-aged participants, subjects had to remember a series of digits ranging from 2 to 5 numbers, recall them in the reverse order and additionally react to suddenly appearing pedestrians. Cognitive workload was assessed by a head-mounted detection response task (DRT). It was hypothesized that with increasing difficulty of the cognitive task, hence increasing cognitive workload, reaction times to the DRT as well as brake reaction times to the pedestrian increase. DRT reaction time increased significantly with ascending number of digits. However, increasing cognitive workload did not affect brake reaction times in this setting. One reason might be the strong salience of pedestrians as a stimulus, leading to no increase in reaction time.