Salt-acid confusion on the single fungiform papilla: effect of changing acid sensitivity.

Individual fungiform papillae were tested for salt-acid misidentification (confusion) to NaCl and citric acid stimulation. Adapting conditions shown either to enhance the intensity or decrease the intensity of citric acid failed to modify the intensity of NaCl. Nor did these adaptation conditions change the frequency of "acid" reports to NaCl or "salt" reports to citric acid. The papillae varied in their tendency to induce the salt-acid misidentification. Salt-acid confusion existed in the absence of "stinging" tactile sensations and varied in degree between 2 papillae within the same subject.