Oral perception of bolus in healthy young women.

This study was designed to characterize oral perception of both weight and volume of boluses. A total of 80 healthy young female subjects was recruited and divided into bolus weight (n = 40) and bolus volume (n = 40) conditions. Tap water (25 degrees C) was the experimental material, and seven reference stimulus amounts ranging from 10 to 40 (grams and mL) were prepared. The reference stimuli, including a modulus of 20 (grams and mL), were delivered to the subjects in randomized order. The estimated magnitudes (psi) conformed to both the Fechner's and Stevens' psychophysical laws by the following equations: (1) psi(W) = 314.3 log (S+1) - 300.2 where S is stimulus intensity or weight, and psi(V) = 249.7 log (S+1) - 222.3 (volume) on logarithmic (log)-linear scales, and (2) psi(W) = 1.908 S1.297 and psi(V) = 4.097 S1.032 on log-log scales, respectively. The results indicate that oral perception of bolus weight and bolus volume conforms to the representative psychophysical laws.