VIBROTACTILE LETTER RECOGNITION - EFFECTS OF A MASKING STIMULUS

A series of experiments examined the effect of masking stimuli on the ability of human observers to recognize letters of the alphabet through their fingertips. The letters were generated on the 6 .times. 24 vibrotactile array of the Optacon, a reading aid for the blind. Letter recognition was interfered with by the presence of masking stimuli occurring at the same site on the skin either before (forward masking) or after (backward masking) the target letter was presented. Backward masking generally interfered with letter recognition more than did forward masking. Backward masking was particularly effective for letters in which the information critical for identification is located on the right side of the letter. Presenting the letters reversed resulted in more forward masking for those letters with critical information now located on the left side. Increasing the time between the target letter and the masking stimuli resulted in improved letter recognition. The implications of the results for tactile reading were discussed.