A COMPARISON OF THE DETECTION THRESHOLDS OF ODOR MIXTURES AND THEIR COMPONENTS

It was the purpose of the present study to investigate whether the perception of odour mixtures differs from the perception of their components with regard to (i) the reliability of detection threshold measurements and (ii) the threshold values themselves. Detection thresholds for a variety of unmixed odorants and 3-, 6- or 12-component mixtures were determined for a total of 44 subjects, tested repeatedly in five separate sessions using sniff bottles and an ascending staircase method. Threshold determinations for the mixtures were found to be as reliable as for the unmixed substances, with intra- and interindividual variability in threshold values actually decreasing with increasing stimulus complexity. The four mixtures for which a systematic comparison of the threshold values of components in the mixed and unmixed state was conducted failed to provide evidence for the hypo-additive effects of compromise or compensation, but rather suggested a positive, sub-threshold interaction between components and possibly even enhancement. Finally, a significant improvement in individual threshold scores was seen across test sessions, with experienced panelists showing the most stable performance.