The Olfactory Process and its Effect on Human Behavior

The Olfactory Process and its Effect on Human Behavior

Early childhood memories can be evoked by many triggers, of which one of the most powerful is a particular smell. A couple of years ago, I was unpacking boxes of Christmas decorations from the attic. One of the boxes contained old, partially melted candles that were to be put on the fireplace mantle and lit on Christmas Eve. Unrolling each uniquely fragrant candle from the yellowed newspaper, I suddenly had a vivid recollection of a childhood experience. I was between the ages of two and three, wandering through a candle store with my parents in the Greek section of Detroit, Michigan. I gazed wide-eyed at the seemingly endless shelves of wax figurines, reaching through the restraining arms of my father in attempts to feel their smooth contours. After slowly returning to reality, I realized that the smell of the candles being used to decorate for the holidays triggered my earliest memory of childhood. I thought about the memory frequently after that, and longed to return to the store to see if my physical presence there would evoke other memories. When I visited Detroit a few months ago, I was disappointed to discover that the store had long been out of business and only my new memory would remain.

I found it somewhat disturbing that my earliest memory was of an insignificant retail store that would have no bearing on my adult life. Why did I not remember a more significant event, such as an early Christmas, or my second birthday? The answer is that the sense of smell, that is, olfaction, has a powerful command over many behaviors, including memory. Intrigued with this connection as an example of sensory input influencing behavior, it is my goal to examine the neurobiology of the olfaction process in humans and to investigate the ways in which odors elicit particular behaviors.

For humans, olfaction is a primitive sense, whereas other mammals, birds and insects rely predominately on their sense of smell for survival. The approach of a charging bear would be recognized by a human within seconds of its attack, while a dog would have certainly caught his scent long before the human companion had any knowledge of the bear's presence. Although smell seems far less meaningful to humans, there is an important link between olfaction and behavior. For example, in my memory described above, the simple visual cues provided by the sight of any ordinary candle does not evoke my memory of the sweet smelling store.