Fragrance (also perfume, olfactory, or scent) is the odor of flowers and other growing things. It is the combination of essential oils or other chemical compounds and may be diluted with alcohol or other solvents. Perfume is often associated with romance, seduction, and arousal. It has also been found to increase perceived attractiveness. Despite its prominence in culture, research on fragrance is relatively sparse. Perfume has been studied as a reinforcer, but the interplay between conscious and neurobiological processes is not well understood.
The olfactory sense is the human organ that perceives odors and sends them to the brain, where they are perceived as pleasure or unpleasantness. The olfactory system is composed of three parts: the nose, the olfactory bulb, and the limbic system. A combination of these components sends signals to the hippocampus and amygdala, which have been linked to emotion, memory, and reward. Interestingly, the receptors in the nose are also linked to sexual function and cognition.
Perfume has been used since ancient times, but only during the eighteenth century did it become an integral part of fashion. It was considered to be a sign of wealth and class, and different perfumes were created for the aristocracy, bourgeoisie, and middle classes. Aristocrats were expected to change their perfumes daily.
A perfume is a mix of different fragrance notes that are combined to create a harmonious scent accord. A perfume’s olfactory qualities can be described using musical metaphors; the top notes (also called head notes) produce the initial impression of the scent and evaporate quickly, followed by the deeper middle notes that develop as the top note fades, and finally the base notes emerge. These are the more intense scents that remain for two minutes to an hour after a person has applied the perfume.
There are many types of perfume, and their names are derived from the ingredients they contain. Depending on the concentration of the perfume, it can be referred to as an eau de parfum, eau de toilette, or eau de parfume concentrate, or simply as EdP, EdT, or EdC. Perfume ingredients are either natural or synthetic. Natural perfumes are based on plant extracts, while synthetic ones are synthesised by chemical companies using natural or non-natural raw materials such as aldehydes, alcohols, and esters.
Throughout most of history, perfume wearing and the use of certain fragrances were ungendered, with both men and women using them in equal proportions. However, during the nineteenth century, with the rise of germ theory and the belief that smells accompanied filth and illness, the public perception of perfume changed. It became a distinctly feminine fragrance, and the smell of floral blends and citruses was deemed exclusively feminine, while scents such as woody or musk-based perfumes were viewed as masculine. This resulted in a gender stereotype of perfume types and usage, which continues to this day. This article argues that future innovative research into the neurobiological underpinnings of perfume, including its rewarding properties, will help to dispel these stereotypes and allow people to choose their perfume according to their individual preferences.