The smell map: is there a commonality of odour perception?

The normal perception of odour quality is poorly understood, so formulating meaningful tests of olfaction is difficult. While tests of odour discrimin ation and odour detection threshold have helped quantify olfactory dysfunct ion, there are not yet predictive relationships between sensitivity to part icular odours and particular forms of olfactory dysfunction. Using 11 commo nly encountered odours, 20 normosmics performed similarity ratings of odour pairs. Multidimensional scaling, a standard behavioural sciences data anal ysis method, was used to explore the perceptual relationships between the o dours based on their pair-wise similarity ratings. Smell maps were created for each individual as was a common or archetypal map which indicated a com monality in individuals' odour perception, far greater than chance alone (P < 10(-6)). A preliminary analysis of four hyposmics suggests that they do not conform to the normosmic archetype. Future studies assessing the relati onship between odours in the archetype should improve the selection of odou rs to be included in tests of odour discrimination.