Enriquez, M. J., MacLean, K. E. (2008). "The Role of Choice in Longitudinal Recall of Meaningful Tactile Signals", in Proceedings of the IEEE Symposium on Haptic Interfaces for Virtual Environments and Teleoperator Systems, pages 49-56, Reno, Nevada, USA, March 2008. (Best Paper: Haptics Science award).
Haptic icons (brief tactile stimuli with associated meanings) have the potential to convey abstract information through touch; however, there has been little systematic investigation of how sets of perceptually distinct tactile signals can be best utilized to convey meanings, nor of how enduring these associations can be. We hypothesized that when users can choose the signals which will represent specific concepts, their learning and recall will be eased and enhanced. Taking future embedded interfaces as context, we used two sets of 10 distinct tactile signals to compare recall of concept-meaning associations in two conditions: (1) arbitrarily assigned and (2) participant-chosen associations. Participants learned associations in under 20 minutes at 80% accuracy; at 2 weeks, recall of the associations previously learned was 86% with no significant effect of assignment condition. Subjective confidence levels sharply lagged actual performance, with zero expectation of ability to recall at 2 weeks. To the best of our knowledge, this is the first study of either longitudinal recall or the role of user choice on synthesized stimulus-meaning learnability. Its results underscore the eminent practicality of using haptic icons in everyday interface design, suggesting high learnability and a surprising user ability to find their own mnemonics for carefully composed stimuli, regardless of how associations are assigned.