| Interaction with mobile devices suffers from a number of shortcomings, most of which are linked to the small size of screens. Artificial tactile feedback promises to be particularly well suited to the mobile interaction context. To be practical, tactile transducers for mobile devices must be small and light, and yet be capable of displaying a rich set of expressive stimuli. This thesis introduces a tactile transducer for mobile interaction that is capable of distributed skin stimulation on the fingertip. The transducer works on a principle that was first investigated because of its potential application to the display of Braille. A preliminary study was conducted on an earlier version of the transducer. It concluded that subjects were able to identify simple Braille characters with a high rate of success. Then, a complete re-design of the transducer addressed the goal of integration in a handheld prototype for mobile interaction. The resulting device comprises a liquid crystal graphic display co-located with the miniature, low-power, distributed tactile transducer. Next, it was needed to measure the perceptual differences between the stimuli that the device could display. Our experiences with one evaluation approach raised questions relating to the methodology for data collection. Therefore, an analysis of the process was carried out using a stimulus set obtained with the device. By means of multidimensional scaling analysis, both the perceptual parameters forming the stimuli space and the evaluation technique were validated. Finally, two experiments were carried out with the objective to develop new mobile interactions paradigms that combined visual and tactile feedback. Both experiments modeled a list scrolling task on the device. The first experiment found a marginal improvement in performance when tactile feedback was employed. It also came at a higher attentional cost dedicated to operating the device. For the second experiment, the scrolling paradigm and the tactile feedback were improved. This lead to a decrease in the reliance on vision when tactile feedback was enabled. Results showed a 28% decrease in the number of key presses that controlled the visibility state of the scroll list. |
