This thesis aims to decrease the feeling of tiredness related to an on-going monotonous, undemanding driving task. It is not intended to enable people to drive longer, but rather for them to experience the time they spend driving as more pleasant. The perception of fatigue is considered as a type of discomfort. From this follows the hypothesis that this feeling of tiredness develops according to a similar system as the perception of discomfort or comfort. Following this premise, the approach in this thesis is to alter the interaction with the vehicle interior by developing features resulting in certain bodily sensations that contribute to feeling more fit. Before developing concepts for this, however, it is first necessary to develop an understanding of what enables a positive experience. Following a review of existing concepts of user experience quality, it is defined in this thesis that a positive experience is related to pragmatic quality (consisting of need fulfillment and ergonomics) and pleasure (consisting of experiential feelings, well-being and meaning). Moreover, a review of literature concerning driver fatigue theories and countermeasures has been carried out for analysis of the problem. This review showed that driver fatigue consists of physical and/or cognitive fatigue. Physical fatigue is related to perceptual-motor adjustments specific to the driving task (holding and operating the steering wheel, using the foot levers) and to discomfort caused by prolonged sitting. Cognitive fatigue can be subdivided in task-related and sleep-related fatigue. Sleep-related fatigue is considered intervention resistant by most researchers. Task-related fatigue is caused from task-overload or underload. Based on these two analyses, the concept in this thesis is to achieve a vitalizing experience by offering stimulation through physiological impulses or physical variety. The first is inspired by the fact that stimulation with local cooling and scent is related to physiological activation. The second is inspired by the fact that posture variation is related to beneficial effects on physical fatigue, and that body movements are also an intuitive countermeasure against cognitive fatigue. Moreover, it is proposed that a positive driving experience in the context of travelling over longer periods of time ensues when the vehicle occupant feels fit upon arrival (need fulfillment). Furthermore, the sensory stimulation should result into bodily activation and reduced strain from travelling by car (ergonomics). Well-being should result from pleasant stimulation of the senses leading to human body effects that avoid a feeling of tiredness. The bodily sensations should be altered in such a way that this leads to experiential feelings that are positive in terms of valence and arousal. Finally, to create a vitalizing driver experience the interaction should be associated positively to refreshment, or should be an intuitive countermeasures against fatigue. This concept is evaluated and developed further with user research in laboratory tests. The stimulation principles (physiological impulses and physical variety) are evaluated with user research in laboratory tests to determine if they contribute to this concept of a vitalizing driver experience. In chapter 5, the effects of local cooling on perceived drowsiness, experiential feelings, perceived task load and heart rate are investigated during a simulated, monotonous driving task. The results show a significant increase in heart rate related to cooling the hands which indicates physiological activation. The majority of participants (83%) preferred to perform the monotonous driving task with local cooling, although no significant effects on perceived drowsiness and task load were found. The comfort experience could be influenced by personal preferences, since the participants who enjoyed the cooling (47%) experienced it as refreshing, pleasant and stimulating but for those who disliked local cooling (53%) it caused discomfort. The interaction should be improved to increase well-being and possible effects on driving performance should be evaluated. Chapter 6 describes two studies with the aim of finding out to what extent postural variation is allowed by the driving task and how sensitive the human body is to these changes. This results in the definition of a range-of motion for physical variety, which is used for the development of a seat movement system. Chapter 7 aims to investigate the influence of this system moving the vehicle occupant’s body passively. This posture variation is realized by continuously varying the seat configuration, i.e. the seat pan and backrest inclination. The measurements obtained were the observation of body movements and questionnaires on perceived discomfort, seating comfort and experiential feelings. The results show that participants perceive more discomfort and that they move significantly more in the static configuration. The seat’s comfort and support are evaluated significantly better in the dynamic configuration. The dynamic configuration results in participants feeling significantly more active, energetic, stimulated, pleasantly surprised, pleased, comfortable, accepting and calm. The static configuration results in the participants feeling marginally more tired and significantly more bored. Further research should investigate the effects in the context of driving on the road and an actual driving task. Yet, it can be concluded that the continuous movements of the seat have a beneficial effect on objective and subjective indicators of well-being. The study in chapter 8 sets out to investigate the effects of sitting pre-condition on product evaluation. In the evaluation of the seat, a significant difference was found for the softness of the seat (product tactility). There are indications that a product could be evaluated better after an uncomfortable pre-condition. More research is needed, however, to support this hypothesis and to evaluate other rating terms of products with different scenarios of prior activities or conditions. knowledge on the influence of one product experience on the other due to the human senses could be a starting point for designing products or environments differently in order to manipulate the user’s overall experience. This thesis presents insights on what influences the negative perception of drowsiness and what enables a positive experience. The most important finding is that well-being can be influenced by stimulating features in the interface between occupant and car. In the present research, this consists of physiological stimulation via local cooling of the hands and physical variety via movements of the seat. This stimulation offers the on-going variability that counters the monotony which is related to physical and cognitive fatigue. Stimulation by physiological impulses and physical variety has shown beneficial effects on objective and subjective indicators of a positive experience. (Author/publisher)
Samenvatting