Multidimensional analysis of twenty-one odors. Scand. J . Psychol., 1973, 14, 131-137.-The present paper reports an experiment on the application of multidimensional scaling to the sense of smell for the purpose of revealing basic psychophysical dimensions of odorants matched in perceived intensity and varying only in perceived quality. The results showed clear evidence for the existence of individuaI odor spaces, but in apparent contradiction to related studies in the literature individual differences were too large to establish a representative odor space for the whole group. For nearly all individual subjects one of the factors extracted seemed to represent a unique hedonic dimension apparently unrelated to the physical attributes of the odorants. It is suggested that such psychological factors may be as important a basis for the judgment of the similarity of odors as the physical attributes of the odorants. Both the interpretation of multidimensional analysis and the extent to which the sense of smell is analytic or synthetic depend on an understanding of this problem. Postal address: B. Berglund Psychological Laboratories University of Stockholm Box 6706 S-113 85 Stockholm Sweden Scand. J . Psychol. 14