The Interstimulus Interval for Taste: 2. Salt Taste Sensitivity Drifts and the Effects on Intensity Scaling and Threshold Measurement

The effects of demonstrated NaCl residuals from prior tastings were tested behaviourally by tasting successive ascending series of NaCl solutions, using three interstimulus procedures. Both inter- and intra-subject studies were performed. When concentrated NaCl solutions (10–1000 mM) were used the adaptation level was found to rise with successive tastings; mouthrinsing was a more effective method for preventing this rise than a 2 min or a 15 s rest. With low concentrations (distilled water–80 mM NaCl) the tendency for adaptation levels to rise, because of NaCl residuals, was smaller, while mouthrinsing made possible the detection of lower NaCl concentrations. The results are used to explain the variations, found in the literature, for NaCl threshold measurements and power function exponents for NaCl magnitude estimation studies.