Facilitatory spatial interaction with percutaneous electrical stimuli

To measure the effect of a rectangular percutaneous conditioning shock to one finger on subjective magnitude of a suprathreshold test shock to an adjacent finger, Ss equated a contralateral matching stimulus to the test shock. The conditioning shock generally increased the apparent intensity of the test shock. This facilitation was a negatively accelerated function of test-shock current. Larger conditioning stimuli produced greater facilitation. Over limited intervals, time between conditioning and test or test and matching stimuli had no systematic effects.