Few scents are more emblematic of a season than pumpkin spice. One whiff of the combination of cinnamon, nutmeg, and ginger is enough to call to mind cozy sweaters, crunchy leaves, and other hallmarks of fall. Broken down to its components, there's nothing uniquely autumnal about pumpkin spice—the mixture doesn't even contain pumpkin. But thanks to the power of memory and suggestion, it dominates the weeks from September through November.

Perception researchers at Johns Hopkins University are looking into the appeal of pumpkin spice and other nostalgic scents. According to Sarah Cormiea, a Johns Hopkins doctoral candidate studying human olfactory perception, our brains are built to fill in the gaps between physical odors and the associations we have with them.

“You know how, if you're holding a coffee cup, you could rotate it all different angles, so at any point some part of it might be obscured from your view. But you can always recognize that object as the same thing even though all of it is not visible at once,” she explains to Mental Floss. “A similar thing happens to odor. Any odor is a mixture of all different types of molecules, and pumpkin spice is going to have really high overlaps with the smells that come from a pumpkin pie.”

Different sensory mechanisms process smells differently. When the sensory neurons in our nostrils pick up scent molecules, they process the physical components. At this stage of the sensory experience, our nose knows the difference between pumpkin pie and a pumpkin spice latte. Things become more abstract as that information moves up the hierarchy of our olfactory system. Once it reaches the brain's piriform cortex, identifying the odor molecules no longer takes priority. This part of the brain analyzes smell and connects it to experiences we've had with similar scents in the past—which is why a spice mixture can remind us of a squash, or at least our idea of it.

“It’s reflecting your brain's job of filling things in, or sort of rounding up,” Cormiea says of the mechanism.

When our brains fills in the gap between the smell beneath our nose and our past experiences, the result can be emotional. That's why so many people are eager to try a pumpkin spice latte the moment the temperature drops. The aroma is more than just pleasant; it's a reminder of high school football games, back-to-school shopping trips, and Thanksgiving dinners.

This phenomenon can be explained by the layout of our brains. Our olfactory system is close to the areas of the brain responsible for memory and emotional response. So when you smell the perfume your grandma loved, you may have a stronger emotional reaction than you would by seeing clothes she wore. When the smell is associated with autumn—a time of year many people think of fondly—that nostalgia can be especially concentrated.

Pumpkin spice mania is also an example of successful branding. Our association with the name is so powerful that just reading it on a coffee cup can change how we perceive its smell and taste.

“One particular topic we study in our lab is how reading labels of smells changes your experience of them,” Cormiea says. “We think that when you add a label it changes people's conscious experience. We have data where we ask people to rate odors, and when people rate unlabeled odors they rate them differently than when they’re rating labeled odors.”

So would people like pumpkin spice lattes as much if they were called something else and sold at a different time of year? Probably not, but that doesn't mean you should deny yourself the seasonal treat this autumn. Much of your perception of pumpkin spice is your brain working overtime, but that doesn't make the scent—or that muffin or coffee drink—any less enjoyable.