The TDS: a new device for comparing active and passive-guided touch

A problem when comparing active and passive tactile perception of two-dimensional (2-D) stimuli is matching the active and passive tasks on all variables except the one of interest-active versus passive touch. A new computer-controlled device-the tactile display system (TDS)-has been developed to deal with this problem. The TDS tracks an "active" subject's fingertip movements during exploration of a raised line drawing and digitally records this spatio-temporal information. It then guides a passive participant's fingertip over the same path, matching for location and speed. Any difference in performance can thus be attributed to the different conditions (active versus passive) because other variables are held constant.