Fragrance is a combination of chemicals that give perfume and cologne its distinctive aroma. A single perfume can contain up to 200 different chemical ingredients. Perfumery has been a revered art since ancient times; Etruscan women carried scented oils as they walked and Roman gladiators used scented powder to prepare for combat. Despite the importance of fragrance, it has been a subject of little scientific research. In fact, there has been only one empirical study of the reward value of perfume – that conducted by the personal perfumer to Catherine de’ Medici in Renaissance Italy. The author concluded that perfume is an intrinsically rewarding stimulus. However, a more important question is whether it also acts as a reinforcer in the same way that other extrinsic rewards (such as money, power and status) do.
Most people who wear perfume do so because they enjoy the pleasant smell of it on their skin. But there is much more to the perfume experience than a simple pleasure in the aroma. For example, some studies suggest that perfume may act as a social signal of attractiveness, and can be a powerful sexual seduction tool for both men and women.
Perfume contains a wide range of chemicals, from natural raw materials to synthetic aroma compounds. Manufacturers of perfumes and colognes purchase the necessary mixtures of fragrance chemicals from companies that specialize in creating fragrance compositions. These chemical ingredients, which are known collectively as the fragrance compound, are then combined with other additives such as solvents, stabilizers, UV-absorbers and preservatives to produce a final product that is marketed as a perfume or cologne.
Currently, the FDA does not require that manufacturers disclose the individual fragrance ingredients on their product labels. Instead, the industry has developed and maintains a system of “trade secrets” that protects the proprietary blends of fragrance chemicals that make up perfume. The FDA should require disclosure of fragrance ingredients in order to ensure public safety and promote innovation in perfume neuroscience and reward.
It is well known that the olfactory cortex (OFC) and amygdala are involved in sensory and reward processing, and that hedonically positive odors such as perfumes activate these brain regions. It is less well appreciated that the OFC and the amygdala are innervated by dopaminergic neurons, and that the activation of these neurons correlates with the sensation of pleasure.
Although perfume is a highly reinforcing stimuli, to date there has been no empirical research assessing its behavioral role as a reinforcer in humans. The anecdotal evidence of the reward value of perfume is tantalizing and a rich source of material for future innovative research in perfume neuroscience and reward. In particular, it would be interesting to test whether the hedonically positive scent of perfume can also act as an unconditioned stimulus that increases the motivation for other stimuli (such as food) to which it is paired through classical conditioning. If this is the case, it will have profound implications for perfume design and use.