The perception of fragrance is very personal. Every human grows up surrounded by certain stimuli that they associate with either fond or unsettling memories. Who doesn’t smile (and perhaps start salivating in anticipation) when exposed to the odor of Grandma’s cookies baking in the oven? And who doesn’t recoil from the odor of a smelly gym bag that hasn’t been opened in a week? Unless you are anosmic, which means that your sense of smell has been compromised, you probably are only marginally aware of how much you use your sense of smell in your everyday life.
However, there are many things that can affect your sense of smell. Perhaps you have a cold or allergies and your sinuses are inflamed — you might notice that your sense of smell is not as strong in this situation. You may notice that your first “sniff” of a fragrance will give you the strongest first impression – this is normal! It doesn’t take long for the olfactory receptors to become saturated by a certain odor and then you have trouble detecting it later. How many times have you been near someone who seems to have bathed in cologne and you wonder, can’t they smell how strong that cologne is? The answer is, no, they can’t, because they have become essentially immune to the odor – their olfactory receptors have been overloaded with that particular scent and they cannot smell it anymore. Pregnancy is known to enhance a woman’s sense of smell, and the theory is that it is vitally important to the survival of the human species for the mother to be aware of what foods she should avoid as they might be harmful.
Then there is the role of the brain in odor perception. Perhaps someone gives you a yellow candle but does not identify what the odor might be. Automatically, your brain expects one of certain fragrances – perhaps a lemon or citrus blend, perhaps a citrus-floral blend, perhaps a lemon-vanilla blend. But what if that yellow candle smells like blueberry? How do you think you would respond? You would probably think that something was wrong because your brain was already expecting a fragrance from a preconceived group that your brain conjured based on the candle’s color. Or perhaps your brain goes even farther and tricks you into thinking it’s some sort of exotic lemon.
There is also the issue of scent memory. Perhaps you have used that last bit of your favorite cologne, and you buy a new bottle. You feel that you know this fragrance well as you have worn it many times, but perhaps the day you open your new bottle you feel that it does not smell the same as the old one did. You may have the impression that the manufacturer changed the formulation. The only way to know for sure would be to analyze the fragrance through gas chromatography and mass spectrometry, but most of us do not have that luxury, so we rely on our scent memory to guide us. However, scent memory can be erroneous as it is based on our (often fuzzy) memory about the fragrance. The only way for us to compare 2 scents (other than through expensive analysis) is to put both fragrances on a blotter and compare them side by side, and even that method must be handled with care. Each fragrance should be dipped into the fragrance up to the same amount – if one fragrance covers more of the blotter than the other, the perception will be that one is stronger than the other. Also, you have to smell each blotter with both nostrils as one nostril might be more congested than the other. Of course, it’s always best to do a blind test when evaluating fragrance so that the brain’s preconceived notions do not come into play.
In fragrance evaluation, we are faced with perception challenges every day. We are constantly evaluating fragrances that are very similar or perhaps the same. We find that it is very easy to “trick” each other with regard to fragrance perception. Even something as simple as saying, “Do you think these 2 fragrances smell the same?” can prejudice the evaluator into either looking for a difference or looking for a similarity, depending on what he or she wishes the outcome to be. Naming the fragrances is also deceiving – I can’t tell you how many times we have giving an evaluator the same fragrance under two different names and the evaluator automatically assumed that the fragrances were different because the samples were named differently.
So the next time one of your customers says, “This candle doesn’t smell as strong as my previous purchase”, bear in mind that they might be right – or they might not!