Einfluss der Gestaltung absoluter Bedieninteraktionen auf die sensomotorische Leistungsfähigkeit

Abstract

The purpose of this thesis was to explore user interaction with in vehicle information systems (IVIS) during driving and the influence of the interaction design on users’ performance. The main focus was on absolute touchpad interaction. In such configurations touchpad and display area are directly mapped, viz. the absolute finger position on the touchpad area is represented at the corresponding cursor position on the display area. Four experiments were conducted to assess a) how users can cope with unexpected changes in the scaling of the display and touchpad area, b) how sensorimotor transformations can be supported by visual feedback, c) to what extent alternative interaction concepts may surpass the limits of absolute touchpad interaction and d) potential effects of aging on interaction design. Fitts’ Law was employed as the main theoretical framework to assess sensorimotor performance of the users. With respect to the scaling of the interaction environment the findings suggest, that an (unexpected) change of the scaling of the display or touchpad can lead to losses in the efficiency of the interaction. With regard to the design of visual feedback the empirical findings allow to derive recommendations for the design of absolute user interaction. The present experiments, however, also revealed that absolute interaction places high demands on the precision of movement control and produces high error rates during the driving task. Therefore, the use of alternative concepts was tested. One alternative absolute concept relies on considerations of beating Fitts’ law by decoupling the visual and motor level of interaction. Thus, aiming movements can be facilitated without adapting the virtual buttons on the display. Furthermore, gesture-based relative interaction concepts were considered. In these concepts the cursor is positioned independently of the finger position and is moved (relatively) based on individual swipe gestures in the direction of movement. Since gesture-based interaction concepts cannot be treated as continuous aiming movements, an alternative theoretical concept instead of Fitts’ law was chosen to predict the movement time. The results of this thesis indicate that movement time for gesture controlled cursor movements can be modeled by the number of necessary interaction steps. Both theoretical concepts, Fitts’ law for absolute interaction and the alternative approach for gesture-based relative interaction, seem suitable to describe and assess the interaction of younger and older users. Additionally, on the basis of the two concepts and the empirical findings recommendations for an appropriate interaction design with IVIS were derived and presented at the end of the thesis.