COMMITMENTS : Sniffing Our Way Down Memory Lane

A woman washing dishes cries as she inhales the familiar odor of the detergent, the same soap used by her beloved, deceased grandmother.

Another woman loathes the fragrance of roses, a scent she first experienced at her mother’s funeral.

A man is transported back to the frivolous, irresponsible days of high school by the thick odor of patchouli.

Nothing elicits memories with the same emotional punch as odor. Sight, touch and words appear to be equally powerful at retrieving memory content, experts say, but pale next to odor’s almost mystical ability to conjure rich emotions with a single whiff.

The most famous example is Marcel Proust’s “Remembrance of Things Past” (1928), inspired by the fragrance of a petite madeleine dipped in tea. “Whence could it have come to me, this all powerful joy? I was conscious that it was connected with the taste of tea and not cake, but that it infinitely transcended those savors, could not, indeed, be the same nature as theirs.”

Surely Proust had seen many madeleines in bakery windows, had perhaps even asked for a dozen of the spongy cookies and served them to guests. But it was the emotional intelligence of Proust’s nose that eventually led to one of literature’s greatest works.

“People have long claimed that odors are the best way to unlock a memory,” says experimental psychologist Rachel Herz, who is currently comparing the memory retrieval cues of odor, sight, touch and words at the Monell Chemical Senses Center, a nonprofit research institute in Philadelphia. “My preliminary findings are that there is not a difference in the accuracy of a memory based on touch, sight, odor and word. But odor-evoked memories are more emotionally loaded than these other types of cue-evoked memories. Memory evoked by smell is the Proustian kind.”

There are anatomical explanations. The nose is connected through the olfactory pathway in the brain to the limbic system, the area of the brain considered to control memory and emotion. Vision and hearing travel pathways to the brain that are more involved in cognitive functions. Upon first whiff, the brain determines if an odor is pleasurable or not and whether it is a threat. Only after this approach-or-avoid dance does the brain try to identify what we are smelling.

“Our experience of emotion is like a higher order of approach or avoid,” Herz says. “The underlying motive is survival. It may well be that without smell we would not experience emotion.”

With smell memory, the first time is the most memorable. “The first association with an odor” dominates our memory of it, says Trygg Engen, professor emeritus of psychology at Brown University and author of “Odor Sensation and Memory” (Praeger, 1991). An odor is committed in memory by its association to a salient, unique time, place and type of stimulation.

“Smell has no identifiable attributes of its own but exists as an inherent part of a unitary, holistic perceptual event,” Engen says. “It is as if the memory of an odor is protected somehow, so that other experiences don’t interfere with the memory of it, whereas pictures and sounds don’t have that same protective effect.”

Unlike colors and tastes, odors do not have their own names, but are described as smelling “like” something else.

“That is why it is difficult to identify isolated odors outside of context,” says Engen, who, in a 1977 study, found that subjects could identify one out of 10 odors when presented with a selection. The average person with a normal sense of smell can identify about 50% of common odors.

“I have done experiments where people have had full-blown episodic emotional experiences by smelling an odor,” Herz says. “But they can’t name the smell.”

Failing to name that smell is something researchers call “tip-of-the-nose” phenomenon. But unlike tip-of-the-tongue phenomenon, where the first and last letter of a word is recalled along with a word’s number of syllables, a tip-of-the nose experience allows no verbal information.

“Smell is really a recognition system, not a naming system,” Engen says. “Sight and hearing are more cognitive. Smell is emotional and doesn’t have to be rational.

But the emotion linked to a smell is not static. Herz has found that the feeling experienced at the time an odor is sensed can change. Immediately following a painful split with a paramour, a whiff of a signature fragrance is painful. Five years later, the fragrance might bring flashes of pleasure. And a decade later, the fragrance may have a nostalgic effect, recalling young, frivolous, naive romance.

So it’s not that the nose knows a thousand odors, as the folklore has it, but that the nose never forgets , Engen says.

Perhaps this explains the legendary memory of elephants?