Simultaneous and successive cutaneous two-point thresholds for vibration

An array of factors, of a type used in a video-tactile visual substitution system, was used to determine two-point thresholds for vibration on the skin of the back. In the first study simultaneous stimulus presentations using the constant stimulus method resulted in a median threshold of 17.8 mm. In the second study, both simultaneous and successive thresholds were near 11 mm. These results differ from classical studies using touch calipers which give simultaneous thresholds Of 68 mm and successive thresholds of 17 mm.