A Pocket-Size Alphabet Display with Letter Trajectories Presented to Fingers

We propose a pocket-size device that enables users with no prior long-time trainings to intuitively read text letters using only their haptic sense. The device forces the user’s finger-tip to trace trajectories of lowercase roman alphabet characters. In displaying multistroke characters, vibrotactile stimuli are accordingly superposed on fingers so that users can distinguish writing strokes from transient movements of fingers between strokes. Our experiments showed that participants could recognize all alphabet characters. They were able to identify them with an accuracy rate of approximately 80 % when presented at an average rate of 1.4 s/letter. We also showed that the accuracy rate varied slightly depending on holding orientation of the device, and that these identification performances could be obtained after only five-minute training. These results suggest that the access to symbolic information via haptic modalities, which were conventionally considered to be of limited use among people with early blindness, would turn into practical mobile applications for people with late blindness or even people with normal vision.