The influence of adaptation on absolute threshold measurements for olfactory stimuli

A group-test method of determining the mean absolute olfactory threshold to a test stimulus for a group of subjects is described. Probit analysis is employed to evaluate the results. This technique is utilized to measure the change in sensitivity to the test stimulus due to adaptation to the masking stimulus. When the values of the logarithm of the threshold concentration of the test stimulus are plotted against the logarithm of the concentration of the masking stimulus for a pair of odorous materials, a straight line is obtained. It is suggested that the gradient of this line may be used as a measure of the degree of community of odour-property between the pair of substances.