Gustatory reaction time under variable stimulus parameters in human adults

Reaction times and perceived intensities for NaCl solutions were measured in sixteen human adults. Stimulus delivery was by means of a circular piece of solution-soaked filter paper held with forceps. The reaction time (T) decreased and the perceived intensity (S) increased with increasing the concentration (C) of NaCl solution applied to a fixed (78.5 mm²) tongue area. The comprehensive relations among T, S and C can be expressed by the following formulae; $\text{T = a +}\text{b}\text{log(}\text{C}\text{C}{}_0\text{)}$, $\text{T = p +}\text{q}\text{log(}\text{S}\text{S}{}_0\text{)}$, and logS = mlogC + logn, where a, b, p, q, m, n = constants, and S₀ indicates the perceived intensity at the threshold concentration (C₀). Meanwhile, the reaction time decreased and the perceived intensity increased with increasing the stimulated area (A) under a fixed (1.0 M) concentration of NaCl solution. The relations among T, S and A can also be expressed by the following equations; $\text{T = a′ +}\text{b′}\text{log(}\text{A}\text{A}{}_0\text{)}$, $\text{T = p′ +}\text{q′}\text{log(}\text{S}\text{S}{}_0\text{)}$, and logS = m′logA + logn′, where a′, b′, p′, q′, m′, n′ = constants, and A₀ indicates the threshold size of stimulated area.