Haptic Display of Multiple Scalar Fields on a Surface

We present here the outlines of a system for simultaneous presentation of several related data sets to users by means of a multidimensional haptic display. Such a display is preferable to a visual display in some situations, for example when (as in our lab) a nanometer-scale real surface is being both examined and modified by the user, and rapid local feedback from the modifications is needed. We propose that each data set (e.g. each property of the nanosurface) be represented by a different haptic dimension, and that equal increments in the property be represented by perceptually equal increments on the corresponding dimension. Fortunately for this scaling requirement, the results reported here reveal that the “power law,” a simple mathematical function which sensory scientists have found to describe the subjective intensity of many types of real stimuli (Stevens, 1961; Gescheider, 1997), applies to virtual ones as well.