The Effect of Cognitive Load on Auditory Susceptibility During Automated Driving.

OBJECTIVE: We experimentally test the effect of cognitive load on auditory susceptibility during automated driving. BACKGROUND: In automated vehicles, auditory alerts are frequently used to request human intervention. To ensure safe operation, human drivers need to be susceptible to auditory information. Previous work found reduced susceptibility during manual driving and in a lesser amount during automated driving. However, in practice, drivers also perform nondriving tasks during automated driving, of which the associated cognitive load may further reduce susceptibility to auditory information. We therefore study the effect of cognitive load during automated driving on auditory susceptibility. METHOD: Twenty-four participants were driven in a simulated automated car. Concurrently, they performed a task with two levels of cognitive load: repeat a noun or generate a verb that expresses the use of this noun. Every noun was followed by a probe stimulus to elicit a neurophysiological response: the frontal P3 (fP3), which is a known indicator for the level of auditory susceptibility. RESULTS: The fP3 was significantly lower during automated driving with cognitive load compared with without. The difficulty level of the cognitive task (repeat or generate) showed no effect. CONCLUSION: Engaging in other tasks during automated driving decreases auditory susceptibility as indicated by a reduced fP3. APPLICATION: Nondriving task can create additional cognitive load. Our study shows that performing such tasks during automated driving reduces the susceptibility for auditory alerts. This can inform designers of semi-automated vehicles (SAE levels 3 and 4), where human intervention might be needed.

The influence of cognitive load on susceptibility to audio.

In this study we evaluate how cognitive load affects susceptibility to auditory signals. Previous research has used the frontal P3 (fP3) event related potential response to auditory novel stimuli as an index for susceptibility to auditory signals. This work demonstrated that tasks that induce cognitive load such as visual and manual tasks, reduced susceptibility. It is however unknown whether cognitive load without visual or manual components also reduces susceptibility. To investigate this, we induced cognitive load by means of the verb generation task, in which participants need to think about a verb that matches a noun. The susceptibility to auditory signals was measured by recording the event related potential in response to a successively presented oddball probe stimulus at 3 different inter-stimulus intervals, 0 ms, 200 ms or 400 ms after the offset of the noun from the verb generation task. An additional control baseline condition, in which oddball response was probed without a verb generation task, was also included. Results show that the cognitive load associated with the verb task reduces fP3 response (and associated auditory signal susceptibility) compared to baseline, independent of presentation interval. This suggests that not only visual and motor processing, but also cognitive load without visual or manual components, can reduce susceptibility to auditory signals and alerts.

Susceptibility to audio signals during autonomous driving.

We investigate how susceptible human drivers are to auditory signals in three situations: when stationary, when driving, or when being driven by an autonomous vehicle. Previous research has shown that human susceptibility is reduced when driving compared to when being stationary. However, it is not known how susceptible humans are under autonomous driving conditions. At the same time, good susceptibility is crucial under autonomous driving conditions, as such systems might use auditory signals to communicate a transition of control from the automated vehicle to the human driver. We measured susceptibility using a three-stimulus auditory oddball paradigm while participants experienced three driving conditions: stationary, autonomous, or driving. We studied susceptibility through the frontal P3 (fP3) Electroencephalography Event-Related Potential response (EEG ERP response). Results show that the fP3 component is reduced in autonomous compared to stationary conditions, but not as strongly as when participants drove themselves. In addition, the fP3 component is further reduced when the oddball task does not require a response (i.e., in a passive condition, versus active). The implication is that, even in a relatively simple autonomous driving scenario, people's susceptibility of auditory signals is not as high as would be beneficial for responding to auditory stimuli.