j. Soc. Cosmet. Chem., 30, 253-262 (September/October 1979) Perceived fragrance complexity and its relation to familiarity and pleasantness j. STEPHAN JELLINEK D..ragoco, D- 3450 ttolzminden, [Vest Germany and EGON P. KOSTER Psychological Laboratory, Utrecht University, Varkenmarkt 2, Utrecht, The Netherlands. Received December 22, 1978. Presented at I Oth L F.S.C.C. Congress, October I978, Sydney, Australia. Synopsis Fifty-nine subjects (23 male, 36 female) rated the FAMILIARITY of nine odors varying in chemical complexity from single odorous compounds to complex perfumes. The results of these ratings were compared with the results of two experiments in which the same subjects were asked to judge the perceived complexity of the odors and their PLEASANTNESS with a paired comparison method. There was no RELATIONSHIP between the CHEMICAL COMPLEXITY of the stimuli and their PERCEIVED COMPLEXITY. Familiarity and perceived complexity were unrelated both in men and in women. In men there was a significant negative correlation between perceived complexity and preference indicating that men prefer less complex odors over complex ones. There was no correlation between familiarity and preference in men. In women preference was positively correlated with familiarity, whereas there was no relationship between preference and perceived complexity. INTRODUCTION Complexity as a dimension of human perceptual experience has been studied occasionally in the fields of vision, audition, taste and food science. Often, complexity is thought to be linked with other perceptual dimensions such as pleasantness and familiarity. Apart from a recent small-scale study by Moskowitz and Barbe (1) and occasional reports that the pleasantness of an odor mixture increases with increasing complexity (2), very little attention has been given to complexity as a feature of odor perception. Perhaps this is due in part to the poor definition of the concept. When we speak of a complex odor at least four different meanings may be involved. In the first place we may refer to the chemical complexity of the stimulus which is related 253

254 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS to the number of different chemical compounds actually present. Secondly we may mean the physiological complexity of an odor, indicating that in the perception of a particular odor only a few or many different receptor sites may be involved. A single substance may stimulate a number of different receptor sites and therefore be physiologically more complex than another single substance that stimulates only one type of receptor sites. Physiological complexity should be measured by direct electrophysiological methods. In the third place we may mean perceived or psychological complexity referring to the notion the observer obtains about the number of separate impressions that make up the total impression he has of the stimulus. The odors of some pure substances might make the impression of being composed of many different odors, whereas chemically complex odor mixtures might seem psychologically simple because all odors in them blend into one single odor impression. Finally, the notion ofperfumer's complexity has a different meaning still. The perfumer considers a fragrance the more complex, the greater the variety of "notes" on which it is based. A floral bouquet containing, for example, elements of gardenia, lilac and jasmin is to him more complex than a %traight" lilac composition, but less complex than a fragrance which in addition to floral notes also contains woody, fruity, and musky ones. The perfumer tends to associate complexity with sophistication. He considers simple fragrances generally more appropriate for basic functional products such as a skin treatment product, a family soap, an air freshener and complex fragrances more appropriate for products associated with the presentation of the product user to the outside world such as colognes or make-up products. Within the realm of colognes, he considers complex fragrances to be more appropriate for the mature woman, simple fragrances more for young girls or elderly ladies. Also, fragrances worn at social occasions are generally more complex than refreshment colognes for daytime or after-bath use. This use of fragrance complexity on the part of the perfumer assumes that the typical consumer responds to differences in perfumer's complexity, albeit perhaps uncon- sciously. The study by Moskowitz and Barbe (1) used methyl salicylate, caproic acid, isobutyl isobutyrate, methyl disulphide and camphor, as well as all possible 2 to 5 component mixtures of these, as the stimuli. These were rated on a range of attributes including complexity, familiarity and pleasantness by fourteen female subjects. Moskowitz and Barbe found only moderate differences in complexity among these stimuli. There was some correlation between perceived complexity and chemical complexity: the three least complex stimuli were single chemicals, and perceived complexity usually increased with the number of components of the mixture. However, there were contradictions thus one of the single chemicals (isobutyl isobutyrate) was among the highest rated in complexity of the entire set of stimuli. There was no significant correlation between the perceived complexity of the stimuli and their pleasantness or their familiarity, although there was some trend for stimuli rated as more familiar to be rated as less complex (r = -- 0.49). It was the purpose of the present study to obtain a clearer picture of the significance and meaning of perceived complexity of perfumes to untrained subjects, using an array of stimuli more relevant to practical perfumery, and a larger group of test