Thresholds of salty taste among Japanese youth were examined by the previously described procedure of Point Scoring and Integration. (See, The Race Hygiene Vol. 16 (1949), No. 4, p. 11A). The threshold of judgment (Cj) and that of perception (Cp) are givon in concentrations of NaC1 solution in the following table: The range of individual difference may be perceived from the frequency distribution di: grams in Fig, 1. (p. 116) where the full line diagram corresponds to the threshold of perception and the dotted line one to that of judgment. The diagrams on the upper part of the figure are for boys and those on the lower part are for girls. At the uppermost of Fig. 1. dots and crosses serve to show threshold values for salty taste by previous authors, both domestic and foreign. Female persons appear to be inclined in general more sensitive than male persons, although there must be set a reserve considering the circumstances that the present survey mainly dealt with a special age class, viz. adolescence, in which the mental predisposition especially in boys may exert some influence on the result of threshold testing.
Solutions of purified saccharose of beet sugar were used for this purpose and the following results were obtained: Individual variation is visualized in Fig. 1 (p. 122), in the Japanese report, where the frequency distribution against the threshold value is shown for both threshold of judgment (dotted line) and that of perception (full line), the upper diagrams referring to males and the lower ones to females. Higher sensitivity of females may be accepted as a general feature.
In the same way as reported previously, average and range of individual differences of threshold for sour taste among the Japanese racewere determined. In the following table the thresholds are expressed in concentrations of acetic acid. Frequency distribution of threshold of judgment (dotted line) and that of threshold of perception (full line) are shown in Fig. 1 (p. 130) in the Japanese report, separately for males (above) and for females (below).
Threshold of bitter taste for quinine hydrochloride solutions as determined by our Point Scoring and Integration Method are tabulated in the following: These values again are for the age class of adolescence. As to the individual diffrence, famale subjects showed regular curves for frequency distribution with a degree of skewness (Fig. 1, p. 135 lower diagrams), while there is some irregularity in the frequency distribution curves of male subjects (Fig. 1, upper diagrams), especially for threshold of perception (full line), which may be attributed to the difficulty in the technique of our whole mouth procedure, considering the location of the most sensitive region for bitter taste on the root of the tongue.