RECEPTION OF MORSE CODE THROUGH MOTIONAL, VIBROTACTILE, AND AUDITORY-STIMULATION

The potential for communication through the kinesthetic aspect of the tactual sense was examined in a series of experiments employing Morse code signals. Experienced and inexperienced Morse code operators were trained to identify Morse code signals that were delivered as sequence s of motional stimulation through up-down displacements (roughly 10 mm ) of the fingertip. Performance on this task was compared with that ob tained for both vibrotactile and acoustic presentation of Morse code u sing a 200-Hz tone delivered either to the fingertip through a minisha ker or diotically to the two ears under headphones. For all three moda lities, the ability to receive Morse code was examined as a function o f presentation rate for tasks including identification of single lette rs, random three-letter sequences, common words, and sentences. Equiva lent word-rate measures (i.e., product of percent correct scores and s timulus presentation rate) were nearly twice as high for auditory pres entation as for vibrotactile stimulation, which in turn was about 1.3 times that for motional stimulation. The experienced subjects outperfo rmed the inexperienced subjects by amounts that increased with task co mplexity. For example, the former were able to receive sentences at 18 words/min with motional stimulation, whereas the latter, following 75 h of training, were unable to perform this task. The present results and those of other research with tactual communication systems are com pared, particularly regarding estimates of information-transfer rates.