Smell and Memory

A smell can bring on a flood of memories, influence people's moods and even affect their work performance. Because the olfactory bulb is part of the brain'slimbic system, an area so closely associated with memory and feeling it's sometimes called the "emotional brain," smell can call up memories and powerful responses almost instantaneously.

The olfactory bulb has intimate access to the amygdala, which processes emotion, and thehippocampus, which is responsible for associative learning. Despite the tight wiring, however, smells would not trigger memories if it weren't for conditioned responses. When you first smell a new scent, you link it to an event, a person, a thing or even a moment. Your brain forges a link between the smell and a memory -- associating the smell of chlorine with summers at the pool or lilies with a funeral. When you encounter the smell again, the link is already there, ready to elicit a memory or a mood. Chlorine might call up a specific pool-related memory or simply make you feel content. Lilies might agitate you without your knowing why. This is part of the reason why not everyone likes the same smells.

Because we encounter most new odors in our youth, smells often call up childhood memories. But we actually begin making associations between smell and emotion before we're even born. Infants who were exposed to alcohol, cigarette smoke or garlic in the womb show a preference for the smells. To them, the smells that might upset other babies seem normal or even comforting.

In the next section, we'll find out how some people use smell's ability to trigger memory.

Scent Marketing

Advertisers are eager to cash in on the close link between smell, memory and mood. Real estate agents have long used scent marketing as a way of putting clients at ease. Sellers set fresh pie or cookies on countertops to make a house seem comfy and livable. But because there's a limit to how many pies one agent can bake, companies that sell aroma-marketing systems are stepping up. Housing developments, hotels, stores and even car manufacturers are turning to customized scents to help set a mood and maybe even make an impression.

Scent marketing is the latest trick to stand out from the visual and auditory barrage that dominates advertising. These scents, however, are a far cry from the strong smells of incense and patchouli at the bead store. They're subtle and almost imperceptible to the unwitting sniffer. Developers use carefully tuned scents to lure customers into a sense of well-being. Stores that sell shoes or shirts, items ideally not associated with odor, formulate aromas of ivy or crisp linen. Some companies even strive to develop a "brand scent," something that customers will associate with the company as much as a logo.

To learn more about smell and the other senses, sniff out the links on the next page.

....................\\\

Nostalgic smells

Nearly everyone has experienced a moment when a faint fragrance brings a memory of a long-lost moment in time crashing back to the forefront of their minds.

Often we will have forgotten about the event completely, yet it transpires our unfathomable minds have filed it neatly in some unreachable corner of the brain, primed for instant retrieval.

Pungent memories

It may be the perfume worn by a long-forgotten friend, the stench of petrol from a youth spent worshipping motorcycles or the haze of chlorine from summer months lazing by the pool.

It is amazing that a few simple airborne molecules can trigger such vivid recollections.

Dr Alan Hirsch is a US neurologist who specialises in the treatment of people who lose their sense of smell or taste.

Total recall

But at the Smell and Taste Treatment and Research Foundation, which Hirsch runs, he is carrying out research into immediate recall of childhood memories by a particular odour, a phenomenon he refers to as olfactory-evoked recall.

Hirsch believes that the details evoked by nostalgic smells are not as important as the emotions they recall. But our minds reshape these memories, sending them through a rose-tinted filter that redefines them as "good times".

Experiences that may have seemed bad at the time can be reconstructed in our minds to seem better than they were, because they represent periods in our life that are now gone forever.

Idealised childhood

Childhood memories, for example, represent times when we were free from the responsibilities and anxieties of adulthood, so we may redefine them in an idealised way, even though many of the experiences we went through were difficult at the time.

In order to study the different odours that evoked nostalgia amongst the public, Hirsch and his staff canvassed around 1,000 people on the streets of Chicago and asked them which smells stimulated a childhood memory.

Baked cakes

The results were interesting. Baked foods such as cakes and baking bread made up the largest category of nostalgic smells. Other cooking smells such as bacon, meatballs and spaghetti were the second largest category of reported smells.

But people born before 1930 tend to recall the odours associated with nature more than people born in later decades. This may reflect increasing urbanisation after the 30s.

Brain wiring

What is not in doubt is that smell is a powerful sense. The olfactory system, the apparatus responsible for our sense of smell, has a pathway in the brain closely associated with the limbic system. The limbic system contains the amygdala and the hippocampus parts of the brain which are closely associated with emotion and memory respectively.

Human beings tend to emphasise vision over all other senses, but our sense of smell is important enough to evoke its own form of déjà vu. Perhaps the foul and strange smells we experience today will be associated with fond memories in years to come.