The effect of skin temperature on detection of vibrotactile stimuli was measured for vibrations of 30 and 250 Hz. Data for the 250-Hz stimulus supported the results of Weitz (1941), who found that thresholds for 100-, 256-, and 900-Hz vibration varied as a U-shape function of skin temperature with a minimum at about 37°C. Temperature had a negligible effect on sensitivity at 30 Hz. A second experiment examined a range of frequencies between 30 and 250 Hz. Cooling greatly lowered sensitivity only to 150-and 250-Hz stimuli. Warming reduced sensitivity less, but more uniformly across frequencies. I t was concluded that cooling may affect vibrotactile thresholds by decreasing the sensitivity of Pacinian corpuscles; the reason for the decrease in sensitivity due to warming is unclear.Severe cold numbs the sense of touch. Despite the commonplace nature of this experience, relatively little has been done to quantify it. Early studies by Allers and Halpern (1922) and Moore (1910) seemed to reveal that the threshold for punctiform touch varies as a V-shaped function of skin temperature, with a minimum at about 37°C. But in both studies stimulus control and measurement left much to be desired. Later, Weitz (1941) seemed to corroborate the earlier findings. He noted that on hairy skin pressure-sensitive and vibration-sensitive "spots" coincided, and found that thresholds for punctiform vibration also varied as a V-shaped function of skin temperature, with a minimum at 37°C. Weitz concluded that temperature affected detection by altering biochemical processes in mechanoreceptors sensitive to both pressure and vibrotactile stimulation.But recent findings in electrophysiology and vibrotactile psychophysics have challenged the view that punctiform pressure and vibration are always mediated by the same receptors. Pressure receptors tend to be slowly adapting and amplitude-sensitive, vibration receptors quickly adapting and velocitysensitive (Harrington & Merzenich, 1970;Merzenich & Harrington, 1969). Since these different response properties undoubtedly derive from different biophysical processes, it seems questionable that temperature would affect the different receptors in identical ways.One can find out indirectly by psychophysical experiment. At least two receptor populations seem Reprint requests may be sent to: Barry G. Green, John B. Pierce Foundation Laboratory, 290 Congress Avenue, New Haven, CT 06519.to mediate the perception of vibrotactile stimuli: One, composed of so-called low-frequency receptors, reacts most readily to vibrations below about 80 Hz; the other, a high-frequency system, reacts to vibrations above 80 Hz. The high-frequency system is believed to be composed of Pacinian corpuscles (Merzenich & Harrington, 1969; Mountcastle, Talbot, Darian-Smith, & Kornhuber, 1967;Talbot, Darian-Smith, Kornhuber, & Mountcastle, 1968;Verrillo, 1963Verrillo, , 1968, whereas no specific receptor has been identified for the low-frequency system. The obvious question is: Since different receptors may be involved, does ski...