This study demonstrated that individual diversities of taste sensitivi
ty on the anterior tongue are due, in part, to variations in fungiform
taste bud density. Citric acid solutions were delivered to a closed,
spatially-matched (each test site was 43 mm2) flow chamber attached to
the surface of die anterior tongue in 84 subjects. A two-alternative
forced choice, modified staircase procedure was used to derive a detec
tion threshold value for citric acid. The same session also included a
visual analog rating procedure to scale the taste intensity judgement
of five concentrations of citric acid. The taste buds within die cham
ber were distinguished by methylene blue stain and recorded by videomi
croscopy. The sip-and-spit method was used to contrast the spatially-m
atched condition with whole mouth stimulation. We found that detection
threshold values were inversely related to the number of fungiform ta
ste buds, independent of gender or age. Whole-mouth threshold values d
etermined for each subject were always well below the spatially-matche
d threshold values. In addition, the data demonstrated that subjects w
ere able to scale the dynamic range of citric acid solutions. However,
gamma-intercept approached zero intensity as the number of fungiform
papillae decreased. The observed differences in citric acid sensitivit
y and fungiform taste bud density indicated that taste performance on
the anterior tongue in humans varies, in part, with the number of tast
e buds.