In perfumery, a mixture that smells different from its components is called an accord.
However the nose retains its capacity to analyse the accord in order to detect each component.
This is very strange, because the new smell is different from the original ingredients. It is a smell on its own. ThisÂ is done through the olfactory memories.
Let us notethat the accord will be perceived as a smell of its own by everybody, but only the persons who know the ingredients will be able to analyse the accord.
Analysis of smell requires the help of the evolved part ofÂ the brain, particularly theÂ orbitofrontal cortexÂ and the language center.
I have met people who are able to detect the presence in a perfume of the smallest part of an essence that they abhor. Rose or Frankincense for instance.
Their nose does not detect these smells inside the perfume, it is not possible,Â there was too little of them in the fragrance to be detected. I know it well enough, having composed the perfume myself.
What they detect is the emotion that these smells awaken in them, because of their olfactory memories.
These persons did hate rose or Frankincense due to a past trauma. They had been exposed to them in a situation of stress and distress and had memorized these smells associating them with the negative emotions lived during that situation.
Their nose acted as a detector, it detected the presence of the essence associated with distress and notified the danger they represented (according to their personal experience) by reproducing the record of the emotion.
These reflections teach us three things about our nose and olfaction:
The nose has a synthetic perception of scents, thousands of aromatic molecules are identified as a single odour.
The nose has an analytic perception of scents, and can be used as an instrument by the brain in order to split an odour in each of its components by name.
The nose can act as a gas chromatography instrument, informing us about the presence of some components in a scent that are of particular relevance to us.
The conclusion is that human olfaction is no less than the one of animals, it is just different. We can smell with our brain in a way no animal can. Human beings, consciously or not, smell more with their brain than with their nose.