A comparison of complex vibrotactile pattern perception on the OPTACON by young and old observers

Abstract

College-aged and, more recently, senior observers are being surveyed for the ability to identify and recognize complex vibrotactile patterns. These patterns are presented to the left index fingertip on the 144-pin vibratory array from the OPTACON, a reading machine for the blind, in a ‘‘static’’ mode in which all elements that spatially define the pattern are turned on for its 26-ms duration. Pattern complexity ranges from simple line segments, identified only by number, to the 26 letters of the alphabet. The ability of these observers to discriminate between two simple patterns is first measured. They are then trained to identify these patterns, and are tested in a masking situation. Observers are then trained to identify a larger set of abstract patterns, and finally the alphabet. In addition, two measures of basic sensitivity are taken on both groups: threshold at ten different frequencies (10–400 Hz) of sinusoidal vibration, and the growth of magnitude for suprathreshold levels of four of these frequencies. Comparisons will be discussed. [Work supported by NIDCD.]