Evaulating the impact on driving of the processing of spoken words: experiments with a driving simulator

The potential impact on driving of the processing of a single, auditorially presented word is analyzed in this work. Since driving is, in itself, a rather complex cognitive activity involving the integration and coordination of a multitude of sub-processes, we narrowed the scope of our research and concentrate on one – but critical – task involved in driving, that is driver braking response. If two tasks have to be performed concurrently and both of them require access to a capacity limited system, then performance in one or both of the tasks will dramatically worsen. This is because the two underlying processes compete for access to cognitive resources. It has been shown that both word recognition and driving requires central resources, therefore this two tasks are likely to interfere with each other. In the experiments, participants were required to perform two tasks during simulated driving (the fixed based driving simulator of Transportation Laboratory - University of Padova was used). In the word recognition task, participants had to categorize auditorially presented words. In the breaking task, participants depressed a brake pedal in response to the lead car’s brake lights. The interval of time between the onset of the tasks’ stimuli (Stimulus Onset Asynchrony, SOA) was varied. Breaking responses were substantially slower as the overlap between tasks increased. This finding demonstrates that the processing of a single word hinders driving performance. The experiments carried out have significant implications in the field of road safety. There are many situations that are similar to those studied in the present experiments, such as a cell phone ring, cell phone conversations (even using hands-free kit), in-car passenger conversations, auditory tips from navigation system, auditory alerts from driver warning system, etc.. The present experiments suggest that all of these situations can negatively affect a driver’s response time increasing the likelihood of “near misses” and accidents.