Abstract
The present study was concerned with the masking and pain-attenuating effect of vibration at different levels of intensity of noxious stimulation. Forty Ss were given noxious stimulation in the form of increasingly painful electric shocks in trials where such shocks were presented with and without concurrent vibratory stimulation. The masking or pain-attenuating effect of the vibration was greatest at the lowest level of noxious stimulus intensity and decreased as the noxious stimulation intensity increased. At the highest level of noxious stimulation the effect of vibration was not significant although there was a tendency for Ss with higher pain tolerance to show summation. The possible relevance of the intensity of the vibratory stimulus to this pattern of results was discussed.