Ternes, D., "Building Large Sets of Haptic Icons: rhythm as a design parameter, and between-subjects MDS for evaluation", M.Sc. Thesis, University of British Columbia, 2007.
Haptic icons (brief, tactile stimuli with associated meanings) are a useful new way to convey information through the modality of touch, but they are difficult to create because of our lack of understanding into what makes good haptic stimuli and how people will perceive them. This thesis aims to enlarge our capabilities to design and evaluate haptic icons, despite these problems. We seek to do this via two overlapping threads of research. In the first thread, we introduce the design parameter of rhythm as a means of extending the expressive capabilities of the simple tactile stimuli used in haptic icons. This allows us to create a set of expressive and perceptually distinguishable haptic stimuli larger by almost an order of magnitude than any previously created. In the second thread of research, we tackle the problem of how to evaluate the perceptual characteristics of such a large set of stimuli with real people. We develop a means of evaluation that allows us to collect perceived difference data by present each user with only a subset of the total stimulus collection, and then stitch together an aggregate picture of how the stimuli are perceived via data collected from overlapping subsets from different users. To advance these two threads of research, two user studies are run in order to examine how our haptic stimulus set is perceived and to validate our new method of gathering perceptual difference data. One study uses an established but cumbersome technique to study our stimulus set, and finds that haptic rhythms are perceived according to several different aspects of rhythm, and that users can consistently differentiate between haptic stimuli along these aspects. The second study uses our newly developed data collection method to study the same stimulus set, and we find that the new technique produces results that show no significant difference from the established technique, but using a data collection task that is much quicker and less arduous for users to perform. We conclude by recommending the use of our new haptic stimulus set and evaluation technique as a powerful and viable means of extending the use of haptic icons to larger sets.