The Connections Between Smell, Memory, and Health
The ability of odors to bring to mind past experiences has intriguing scientific and therapeutic implications.
“What can you do with your nose?”
That’s the question psychologist Donald Laird posed in a 1935 paper — one of the first studies exploring links between odor and memory. Even as many of his contemporaries in sensory neurobiology were preoccupied with vision, and prominent scientists, including Darwin and Freud, had disparaged humans’ sense of smell, Laird, a Colgate University professor, argued that olfaction had been unduly dismissed. “Even our contemporary psychologists,” he wrote, “with dignified aplomb, casually pass by the sense of smell as something that is notable among animals but sadly deficient in mankind.”
Laird had an inkling that the human nose could do more than it got credit for, that it could even hold clues to the inner workings of memory. So he and colleagues asked 254 study participants to record moments in which smells spurred flashbacks to the past. They received hundreds of anecdotes, from a whiff of perfume reviving the discomfort of an awkward dance class to the smell of wool recalling a long-lost uncle’s overcoat. One participant, the son of a sawmill worker, reported that the smell of sawdust brought on “a series of vivid pictures so graphic that for the moment I live the scenes again.” The mere sight of sawdust, in contrast, fell flat.
The memories these passing odors evoked were remarkably intense, emotional, and deep-seated — more than just “casual will-o’-the-wisps in our mental fabric,” Laird wrote. The study’s insights provoked a bigger question about smell: “Can this be a sense which educators have overlooked,” he posited, “as an avenue into the mind?”
Fast-forward nearly a century, and scientists are making strides in understanding the connection Laird intuited — and even harnessing it to improve health. “It’s now clear that even though our sense of smell is not as robust as that of a mouse or bloodhound, it is deeply tied to our cognitive centers, our emotional centers, and our memory centers,” says Sandeep Robert Datta, a professor of neurobiology at Harvard Medical School. “We’re dependent on it for a sense of well-being and centeredness in the world.”
How smells trigger memories
Datta, whose HMS lab studies how animals use senses to understand the world around them, says that neuroscience has revealed the mechanisms behind odor’s power to spur memory — a power with evolutionary origins. Our ancient ancestors relied on smell to build maps of their surroundings and remember where they’d been. “You can think of the original brain as being a sense of smell plus a sense of navigation plus a sense of memory,” Datta says. “That explains why all those structures are so intimately connected, and why odor memories are so evocative.”
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