You catch a whiff of pumpkin pie, school glue, newspaper, or fresh-cut grass and suddenly you’re immersed in a flurry of vivid memories, often from your childhood. What is it about smells that can trigger memories so strong and real it feels like you’ve been transported back in time?

It’s known as “odor-evoked autobiographical memory” or the Proust phenomenon, after French writer Marcel Proust. In his famous novel In Search of Lost Time, the narrator dips a madeleine cookie into a cup of tea and is transported back into time as long-forgotten memories of his childhood come flooding back.

Indeed, research shows that odors are especially effective as reminders of past experience, much more so than cues from other senses, such as sights or sounds.¹

One reason this might be has to do with the way your brain processes odors and memories. Smells get routed through your olfactory bulb, which the smell-analyzing region in your brain. It’s closely connected to your amygdala and hippocampus, brain regions that handle memory and emotion.

The close connection may explain why a scent might get tied to vivid memories in your brain, and then come flooding back when you’re exposed to that particular odor trigger. As noted by Psychology Today:²

“Interestingly, visual, auditory (sound), and tactile (touch) information do not pass through these brain areas. This may be why olfaction, more than any other sense, is so successful at triggering emotions and memories.”

Odor-Cued Memories Tend to Be Stronger, More Emotional, and from Earlier in Life

Before reaching your thalamus, smells first wind their way through other regions of your brain, including areas controlling memory and emotion. So with scents, you have all this extra processing even before you have conscious awareness of the scent.

Your body also contains far more receptors for smells (at least 1,000) than it does for other senses, like sight (four) and touch (at least four).³ What this means is you can discern between many different types of smells, even those you may not have the words to describe.

Taken together, this makes odor-cued memories particularly poignant and different than other memories. In one study of older adults, for instance, the participants were given three cue types (word, picture, or odor) and asked to recall memories triggered by the cue.⁴

It turned out the odor-cued memories tended to be older memories from the first decade of life, whereas those associated with verbal and visual information were from early adulthood.

The odor-evoked memories were also associated with “stronger feelings of being brought back in time” and had been “thought of less often” than memories evoked by the other cues.

Separate research also revealed that both young and old adults were able to recall more than twice as many memories when they were associated with an odor, which according to researchers provides “evidence for substantial olfactory cuing that is remarkably intact in old age.”⁵