Does fresh-cut grass instantly transport you to the soccer field you played on as a kid? Do lilies remind you of your grandmother’s perfume? Everyone’s experienced this at one time or another: You could all but forget a memory, just for a random whiff of something to bring it, quickly and intensely, to the forefront of your mind.
To put it simply, your sense of smell is super emotive and the sense that’s most closely linked to memory. Even without necessarily putting words to it, we remember smells pretty distinctly. In fact, we can’t really put words to smells. Think about it: You either describe smells as “like so-and-so” or you name a smell from the thing it comes from.
“That smells like clean laundry.” “It’s coconut-scented.” Right?
But the neurological reasoning is actually pretty fascinating. Our sense of smell is the most rudimentary, being the sense with the longest evolutionary history, meaning organisms were connecting chemical smells before seeing or touching anything.
As far as our brains, the sense of smell has at least 1,000 signal receptors, while other senses only have about four. So, smell’s already at an advantage within the confines of our brains.
More than that, though, all sensory information from sight, hearing, touch and taste go through a neurological relay center called the thalamus before moving on to the hippocampus (which is responsible for creating memories) and the amygdala (the emotional processing hub). Smell, though, bypasses the thalamus altogether and moves right to the olfactory bulb, or smell center, which can also store long-term memories. The olfactory bulb is directly connected to the hippocampus and amygdala, so the memory connection and emotional processing are more immediate.
Thus, getting a whiff of something results in a swift, intense memory and attached emotion -- whether you like it or not!