Salt taste sensitivity and stimulus volume: effect of stimulus residuals.

Sodium chloride (NaCl) stimulus residuals were seen to be greater after a large-volume NaCl rinse than after a small-volume rinse. Predicted changes in sensitivity dependent on adapting concentrations determined by residual levels were confirmed by signal detection R-index measures of sensitivity. R-index values were seen to be independent of the volume of the test water and NaCl stimuli used in their determination.