Three experiments are reported bearing on Katz's hypothesis that tactile texture perception is mediated by vibrational cues in the case of fine textures and by spatial cues in the case of coarse textures. Psychophysical responses when abrasive surfaces moved across the skin were compared with those obtained during static touch, which does not provide vibrational cues. Experiment 1 used two-interval forced-choice procedures to measure discrimination of surfaces. Fine surfaces that were readily discriminated when moved across the skin became indistinguishable in the absence of movement; coarse surfaces, however, were equally discriminable in movingand stationary conditions. This was shown not to result from any inherently greater difficulty of fine-texture discrimination. Experiments 2 and 3 used free magnitude estimation to obtain a more comprehensive picture of the effect of movement on texture (roughness) perception. Without movement, perception was seriously degraded (the psychophysical magnitude function was flattened) for textures with element sizes below 100 llm; above this point, however, the elimination of movement produced an overall decrease in roughness, but not in the slope of the magnitude function. Thus, two components of stimulation (presumably vibrational and spatial) contribute to texture perception, as Katz maintained; mechanisms for responding to the latter appear to be engaged at texture element sizes down to 100llm, a surprisingly small value.In his classic treatise The World of Touch, David Katz (1925 advanced the view that the tactile perception of the texture of surfaces is a complex process, depending on a "spatial sense" for discernment of coarse textures and a "vibration sense" for an appreciation offiner textures. Katz offered a number of ingenious observations to support his theory: For example, he demonstrated that papers can be discriminated by an observer drawing a wooden rod across them but that wrapping the rod in cloth greatly impairs performance (p. 115). These results suggest the use of vibrational cues. Katz's view, referred to here as the duplex theory oftactile texture perception, is succinctly captured in his statement that surfaces touched very lightly could not be clearly perceived, because "the spatial sense ofthe skin could no longer discern the coarse texture of the materials, and the vibrations necessary for the recognition of fine texture were lost as a result of the minimal friction" (p. 138).