During the last decades more and more interest has been shown in in-car measures to increase traffic safety. Research has proven that there is a large safety potential in some of these systems. One example of this is the Intelligent Speed Adaptation (ISA), which has shown, among other things, reductions in mean speeds and speed variance (see for example Hjälmdahl et al 2002; Regan et al 2005). The effect of changes in mean speed alone was estimated to lead to between 8 % and 25 % reduction in injury accidents and between 10 % and 32 % reduction in fatal accidents under the assumption that all cars were equipped with an ISA in form of an Active Accelerator Pedal (AAP) (Hjälmdahl et al 2002). To materialize these safety improvements the systems has to be used. The driver acceptance of these systems therefore becomes central. Previous study has shown how the general assessment of the concept of an in-car system (AAP) was very positive while the “close to action” statement about the willingness to keep the system was rather low (Adell, Várhelyi 2007). This contrast raises an important question of what acceptance is and how it can be measured. As Regan et al (2002) stated: “While everyone seems to know what acceptability is, and all agree that acceptability is important, there is no consistency across studies as to what ‘acceptability’ is and how to measure it”. There has been some work dealing with acceptance measurements (for example van der Laan et al 1997), but none has offered a satisfactory definition. As long as the meaning of “acceptance” is not defined, comparing results from different studies is very hard. Further, the lack of definition increases the risk of unreliable and/or biased assessments due to the purpose of the study and/or the skill of designing surveys. Work is ongoing with adapting the UTAUT acceptance model (used in information technology) (Venkatesh et al 2003) to in-car driver support systems. First results will be presented at the workshop. The presentation also aims at starting a discussion on the definition of acceptance and how acceptance is created. (Author/publisher) This publication may be accessed by Internet users at: http://www.ictct.org/workshop.php?workshop_nr=25
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