Have you ever caught a whiff of something and suddenly been thrust back to another time and place? I know that whenever I smell a particular ginger/molasses aroma, I am instantly back in the warm cozy kitchen of my grandmother Margaret. Scientists have a name for this: The Madeleine Effect. This is based on a passage written by Marcel Proust in Remembrance of Things Past. He describes how the fragrance of a madeleine cake dipped into linden tea suddently sent him back to his childhood. When a strong memory is evoked by catching a sudden sniff of a scent, "the madeleine effect" is present.
This reference is found in an article in the current issue of Scientific American Mind. Author Eleonore Von Bothmer points out that the sense of smell is one of the oldest senses, from an evolutionary point of view, and is strongly associated with emotions and memory. Interestingly, loss of smell may be indicative of some neurodegenerative diseases. For example, at the onset of Parkinson's and Alzheimer's, people frequently lose their ability to smell.