I often go with my friend and her chihuahua Abby to Abby’s favorite place in the world, which is a large open prairie field at Beaudry Park. It’s the only place she can run around all she wants without encountering her least favorite things: other dogs, and human children.

Sometimes there’s a line of cylindrical haybales at the edge of the big field. One time, my friend stuffed a chicken treat into one of the haybales, low to the ground so Abby would find it. After retrieving it, Abby went straight to the same spot on the next haybale, looking for the chicken that all haybales apparently contain.

We laughed, but humans are the same. Every time I go near the Assiniboine Park neighborhood, I’m helpless not to think of a nearby ice cream parlor called Sargent Sundae. In fact, I can’t even think about that area of the city without entertaining the possibility of working an ice cream sortie into my day. I suppose that’s natural; remembering food locations is undoubtedly one of the main reasons our minds developed the tendency to make such quick associations.

The human mind is a high-horsepower free-association machine. Walk down a street you lived on as a child and notice the memories flood in, in astonishing detail — not just what grade you were in, who your friends were, and what you did on Saturday mornings, but the threadbare armrest on the basement easy chair, the sun-discolored cassettes that lived on your sister’s windowsill, and your pink-and-turquoise bouncy ball – the one with teeth marks in it — that ended up in the eavestrough.

Your memory banks contain millions of such details, and they shoot to the surface at the slightest provocation, each with their own emotional signature. The crunch of gravel driveway summons an image of the old grey Buick and its pungent air freshener. By just glancing at the old aluminum screen door, you can almost hear how it groaned when you opened it too wide.

With a hair-trigger, the mind connects what’s happening in the present to anything in its vast archives that might be relevant. It’s doing this virtually all the time, which is what allows us to remember where we live, what a ripe avocado feels like, and other important predictive information.
This article was hard to excerpt because David's introductory thoughts frame the whole but it increasingly becomes more and more fascinating.

How to Get out of Your Own Head — by David Cain