Figure 1. Exemplars of Human-Computer Integration: extending the body with additional robotic arms; [70] embedding computation into the body using electric muscle stimulation to manipulate handwriting [48]; and, a tail extension controlled by body movements [86].

Passive Haptic Learning (PHL) allows people to learn "muscle memory" through vibration stimuli without devoting attention to the stimulus. PHL can be facilitated by wearable computers such as gloves with an embedded tactile interface. Previous work on PHL taught users rote patterns of finger movements corresponding to piano melodies. Expanding on this research, we are currently exploring the capabilities and limits of Passive Haptic Learning as we investigate whether more complex skills and meaning can be taught through wearable, tactile interfaces. We are creating and studying a system for passively teaching typing skills, with the ultimate goal of passively teaching Braille typing. Our initial studies in perception and learning provide key information for system development including the importance of visual feedback in learning to type; while our pilot study using the current system for Passive Haptic Learning of typing on an unfamiliar keyboard shows passive learning in all participants.

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Passive Haptic Learning (PHL) is the acquisition of sensorimotor skills without active attention to learning. One method is to "teach" motor skills using vibration cues delivered by a wearable, tactile interface while the user is focusing on another, primary task. We have created a system for Passive Haptic Learning of typing skills. In a study containing 16 participants, users demonstrated significantly reduced error typing a phrase in Braille after receiving passive instruction versus control (32.85% average decline in error vs. 2.73% increase in error). PHL users were also able to recognize and read more Braille letters from the phrase (72.5% vs. 22.4%). In a second study, containing 8 participants thus far, we passively teach the full Braille alphabet over four sessions. Typing error reductions in participants receiving PHL were more rapid and consistent, with 75% of PHL vs. 0% of control users reaching zero typing error. By the end of the study, PHL participants were also able to recognize and read 93.3% of all Braille alphabet letters. These results suggest that Passive Haptic instruction facilitated by wearable computers may be a feasible method of teaching Braille typing and reading.

Objective Evaluate the feasibility and potential impacts on hand function using a wearable stimulation device (the VTS Glove) which provides mechanical, vibratory input to the affected limb of chronic stroke survivors. Methods A double-blind, randomized, controlled feasibility study including sixteen chronic stroke survivors (mean age: 54; 1-13 years post-stroke) with diminished movement and tactile perception in their affected hand. Participants were given a wearable device to take home and asked to wear it for three hours daily over eight weeks. The device intervention was either (1) the VTS Glove, which provided vibrotactile stimulation to the hand, or (2) an identical glove with vibration disabled. Participants were randomly assigned to each condition. Hand and arm function were measured weekly at home and in local physical therapy clinics. Results Participants using the VTS Glove showed significantly improved Semmes-Weinstein monofilament exam results, reduction in Modified Ashworth measures in the fingers, and some increased voluntary finger flexion, elbow and shoulder range of motion. Conclusions Vibrotactile stimulation applied to the disabled limb may impact tactile perception, tone and spasticity, and voluntary range of motion. Wearable devices allow extended application and study of stimulation methods outside of a clinical setting.