ABSTRACT
The question of odor quality is more complex, and there have been several attempts to determine whether there are such things as 'primary' odors. Specific odors are represented by points within the triangular prism that indicate the relative contribution of each of the primary odors. The suggestion was that the shapes of the odorant molecules acted as keys that allowed them to bind to specific receptor sites on the surface of the olfactory membrane and hence give rise to specific odors. Unfortunately, research has since demonstrated that molecules with similar shapes can in fact give rise to very different odors, and it appears likely that a range of chemical properties are involved in the determination of odor. There is evidence that sensitivity for this and many other odorants interacts with hormonal variation during the menstrual cycle. Humans have very good memories for the sources of odors and laboratory studies show that smells associated with real-life experiences are particularly long lasting.
