With increasing automation, drivers' roles transition from active operators to passive system supervisors, affecting their behaviour and cognitive processes. This study addresses the attentional resource allocation and subjective cognitive load during manual, SAE Level 2, and SAE Level 3 driving in a realistic environment. An experiment was conducted on a test track with 30 participants using a prototype automated vehicle. While driving, participants were subjected to a passive auditory oddball task and their electroencephalogram was recorded. The study analysed the amplitude of the P3a event-related potential component elicited by novel environmental stimuli, an objective measure of attentional resource allocation. The subjective cognitive load was assessed using the NASA Task Load Index. Results showed no significant difference in subjective cognitive load between manual and Level 2 driving, but a decrease in subjective cognitive load in Level 3 driving. The P3a amplitude was highest during manual driving, indicating increased attentional resource allocation to environmental sounds compared to Level 2 and Level 3 driving. This may suggest that during automated driving, drivers allocate fewer attentional resources to processing environmental information. It remains unclear whether the decreased processing of environmental stimuli in automated driving is due to top-down attention control (leading to attention withdrawal) or bottom-up competition for resources induced by cognitive load. This study provides novel empirical evidence on resource allocation and subjective cognitive load in automated driving. The findings highlight the importance of managing drivers' attention and cognitive load with implications for enhancing automation safety and the design of user interfaces.

翻译：随着自动化程度的提高，驾驶员的角色从主动操作者转变为被动的系统监督者，这影响了他们的行为和认知过程。本研究探讨了在真实环境中进行手动驾驶、SAE L2级和SAE L3级驾驶时的注意力资源分配与主观认知负荷。实验在测试轨道上进行，有30名参与者使用原型自动驾驶车辆。驾驶过程中，参与者需执行被动听觉奇异球任务，并记录其脑电图。研究分析了由新异环境刺激诱发的P3a事件相关电位成分的幅值，这是注意力资源分配的客观指标。主观认知负荷则通过NASA任务负荷指数进行评估。结果显示，手动驾驶与L2级驾驶的主观认知负荷无显著差异，但L3级驾驶的主观认知负荷有所下降。P3a幅值在手动驾驶时最高，表明与L2和L3级驾驶相比，驾驶员对环境声音的注意力资源分配更多。这可能表明，在自动驾驶过程中，驾驶员分配用于处理环境信息的注意力资源较少。目前尚不清楚自动驾驶中环境刺激处理减少是由于自上而下的注意控制（导致注意力撤离），还是由认知负荷引起的自下而上的资源竞争。本研究为自动驾驶中的资源分配与主观认知负荷提供了新的实证证据。研究结果强调了管理驾驶员注意力与认知负荷的重要性，对提升自动化安全性及用户界面设计具有启示意义。