## 3 Interview Results
### Dialogue-Awakening Mechanism Based on the SOR Theory  
By integrating the SOR theory, this study examines the role of conversational activation mechanisms in mitigating driver fatigue (Figure 1). The SOR framework emphasizes the interplay between environmental stimuli (S), internal states of the individual (O), and their behavioral responses (R). Within the context of fatigue driving, specific types of voice-based interactions (stimuli) can influence the driver's physiological and emotional state (organism), thereby altering their alertness and driving performance (response). Based on our interview data, drivers' reactions to voice assistant interactions can be categorized into three types: humorous, mechanical/repetitive, and emotionally neutral dialogues. Each type exhibited varying levels of effectiveness depending on the driver's fatigue state. Humorous and highly interactive dialogues were found to be the most effective in restoring alertness. These interactions enhanced drivers' emotional engagement and reduced monotony, especially during prolonged driving. For instance, P01 (long-haul truck driver) noted, \"_If the assistant tells jokes or asks interesting questions, the journey feels less monotonous and I can stay more alert\"_. Such interactions were particularly effective for drivers experiencing mild fatigue, helping maintain mental focus and reduce perceived strain. In contrast, mechanical and low-emotional-value dialogues--characterized by repetitive content and rigid tone--were reported to be ineffective and often counterproductive. Figure 1: Speech dialog arousal mechanism study model. P06 (long-haul driver) remarked, \"_Sometimes the assistant just repeats meaningless reminders, which irritates me and makes the fatigue worse_\". These findings suggest that repetitive, non-engaging dialogue lacks the emotional stimulation necessary to sustain driver attention and may even exacerbate fatigue. The fatigue level emerged as a critical moderating factor. Drivers with mild fatigue responded positively to lighthearted or interactive dialogue. For example, P02 explained, \"_When I start feeling tired, having light, engaging conversations with the assistant really helps me stay alert_\". However, drivers suffering from severe fatigue displayed diminished receptivity--even to humorous dialogue. P09 admitted, \"_When I'm extremely tired, no joke can wake me up--it just becomes annoying_\". In such conditions, cognitive and attentional resources are already depleted, and over-stimulation through dialogue may further increase the cognitive load, leading to aversion. Therefore, the dialogue content and intervention frequency must be adapted to the driver's fatigue status. In cases of severe fatigue, the assistant should reduce non-essential interactions and instead provide practical suggestions, such as reminders to take a rest or updates on nearby rest areas. As P03 observed, \"_When I've been driving too long and feel exhausted, a simple rest reminder is enough--no need for extra chatting_\". Under the SOR framework, the effectiveness of conversational stimuli is dependent on the driver's internal state. Engaging, humorous dialogues can enhance emotional and cognitive arousal, thereby promoting alertness and improving driving performance. P05 (truck driver) confirmed, \"_Jokes or light conversations help lift my mood and keep me focused_\". These reactions support longer periods of safe driving by alleviating subjective fatigue. Conversely, mechanical dialogues not only fail to produce positive emotional responses but may also intensify feelings of drowsiness or irritability. P04 stated, \"_When I hear those useless robotic prompts, it just ruins my mood and makes me feel even sleepier_\". This reinforces the need for voice assistants to avoid emotionally flat, repetitive content, especially during fatigue-prone periods. In summary, under the SOR theoretical lens, humorous and interactive dialogues can be effective stimuli to counteract mild fatigue by restoring driver alertness.