Persuasive lane use advice provision in relation to driver workload and user acceptance

The effectiveness of lane specific advice is largely de pendent on behavior of tthe users. In the context of lane specific advice, a broad distinction can be made between direct and indirect behavioural adaptation (Martens & Jenssen, 2012). Direct adaptation effects in behavior entail the effects which are realized through the system parameters set by the manufacturer of a system. This is called compliance and it strongly depends on the benefits of the advice as perceived by the driver. However, the device can also have unintended effects on driving behavior. These are called indirect adaptation effects in driving behavior. Examples of such effects are a change in reaction time, lateral position, speed and distance to the lead vehicle, which may have an adverse effect on the efficiency of the system.

Driver workload has been shown to have a substantial effect on direct adaptation effects as well as on indirect adaptation effects. Driver workload is defined as the amount of information processing capacity needed to adequately perform the driving task (Brookhuis et al., 1991). Driver workload is dependent on external circumstances (such as traffic intensity, interaction with other road-users, network characteristics, road geometry, adverse weather conditions, etc.). In addition, the lane specific advice as well as the modality of the advice provision may be assumed to have an influence on driver workload as well, but it is unclear to which extent.

User acceptance has been shown to have a substantial effect on direct adaptation effects in driving behavior as well (Jimenez et al., 2012). It can in this context be assumed that characteristics of the user, the type of advice and the modality through which the advice is provided have an influence on user acceptance and consequently on direct adaptation effects in driving behavior. Besides these factors, it can be assumed that the perceived utility of the lane specific advice al so has an influence on user. However, it is not yet clear to what extent these factors actually have an influence on acceptance of the lane specific advice and consequently on direct adaptation effects in driving behavior. It is however not yet clear to what extent these factors actually influence user acceptance of the lane specific advice.

Changes in driver workload and user acceptance are assumed to lead to direct and indirect adaptation effects in driving behaviour, which may also have an effect on traffic safety, which may be represented by proximal safety indicators such as Time-To-Collision and Standard Deviation Lateral Position. Summarizing, we need to determine (1) the impact of content and modality of the lane specific advice, external circumstances and driver characteristics on driver workload, (2) impact of perceived utility of the lane specific advice, external circumstances and driver characteristics on user acceptance and (3) direct and indirect adaptation effects in driving behavior following from changes in driver workload and user acceptance and the consequences for proximal indicators of traffic safety. Based on these results we will develop the modality and content of the advice constituting the Human Machine Interface to provide la ne specific control aimed at providing an optimal degree of direct and indirect adaptation effects in driving behavior in relation to driver workload and user acceptance.

B1. Lane specific advice and driver workload

Driver workload is influenced by external circumstances, moderated by driver characteristics (Hoogendoorn et al., 2012; Hoogendoorn & Van Arem, 2013). Al so, type and modality of the advice have an influence on driver workload. Research has shown that the modality through which advice is provided has an influence on driver workload. Srinivasan and Jovanis (1997) showed that workload differed significantly when comparing auditory to visual advice provision. Mohebbi et al. (2009) showed that driver workload differed significantly when comparing auditory to haptic information provision of rear-end collision warnings. This work package will start with a n elaborate state-of-the-art review on the main influences of the type and modality of advice, driver characteristics and external circumstances on driver workload. Next, we conduct driving simulator experiments in order to determine the main and interaction effects of driver characteristics, type and modality of the advice and external circumstances on driver workload. Modalities to be considered are auditory, visual and combinations, including he ad-up-displays and using brief motivational messages. Using full factorial experimental designs, the different independent variables will be varied systematically. We envisage to determine driver workload through subjective estimates of effort expenditure (Rating Scale Mental Effort; Zijlstra & Van Doorn, 1989), physiological indicators of driver workload (amplitude of facial muscles, heart rate, heart rate variability) and performance indicators (reaction time; Peripheral Detection Task).

B2. Lane specific advice and user acceptance

User acceptance can be assumed to have an influence on direct adaptation effects in driving behavior. Type and modality of the advice in interaction with driver characteristics and external circumstances have an influence on user acceptance. It is however not clear to what extent the modality of the lane specific advice and other factors have an influence on user acceptance.