Shock-elicited pain and its reduction by concurrent tactile stimulation.

Human affective reactions to nociceptive electrical stimulation were attenuated by application of a tactile stimulus to the shocked site. No alteration was perceived when the same tactile stimulus was applied to a similar contralateral site. These results and a lack of alteration at sensation threshold demonstrate the effect to be more than simple masking and support the Melzack-Wall theory.