Improving Access to Mobile Technologies Using Tactile Feedback

Mobile technologies offer the benefits of portability and ubiquity. However, their reliance on small visual displays and realistic settings (e.g. while on the move) can introduce a variety of usability challenges to users, causing situational-induced impairments and disabilities (SIIDs). While the sense of touch provides one solution to supporting users with SIIDs, the tactile feedback provided by current mobile technologies is relatively simple in nature, often based on the metaphorical associations arbitrarily dictated by interface designers. Furthermore, these cues are yet to be extensively evaluated outside of controlled environments. This dissertation aimed to address these limitations. Firstly, we studied the range of discernible tactile icons (tactons) that can be presented via standard mobile technologies. Findings highlighted the role of intensity in supporting tactile recognition as well as the impact of duration, interval and intensity on task time. We also examined the use of tactons in a mobile exertion application, designed to help individuals monitor and modify walking behavior. Usability tests of the application proved its utility in communicating alerts and promoting physical activity among users. Secondly, we examined the impact of situational distractors (i.e. sound and movement) on the perception of multi-parametered tactons. Results indicated the negative effects of these distractors on recognition accuracy, time taken and cognitive workload. However, some tactile designs (e.g. those encoded with stronger intensities) were found to be able to better resist such effects. Our findings highlighted the importance of evaluating mobile interfaces in more realistic contexts. Thirdly, we investigated the intuitiveness of tactile mappings between tactile parameters (e.g. intensity of vibrations) and message features (e.g. urgency of messages) for mobile notifications. A paired-comparison task was performed. Using this approach, we identified the tactile mappings rated with the highest preference scores. Tactons designed using these mappings were proved to be more effective in field-based settings. The dissertation has culminated in a set of design guidelines relating to the design and evaluation of tactons for use in mobile interactions. These guidelines may help the mobile interface developers to construct effective tactile feedback, and improve users' access to mobile technologies in distracting contexts