Your customers are irrational. You may think you already knew that, but — as recent research suggests — it's true. In fact, we're all irrational. By that I mean that we all perceive the world around us, and make decisions, and act based largely on what's happening in our "irrational" subconscious. Recent evidence suggests fully 95 percent of our cognitive processing is subconscious. That leaves all of 5 percent of the rational mind to do what it does best: rationalize (some might say "guess about") our decisions and actions to ourselves.

What that means is we're pretty poor at telling others what we like or don't like, and why we feel that way. And the science suggests we're even worse at predicting what we might like, or do, in the future. One might wonder then, if we're so horrible at this, just why businesses continue to crank out standardized customer satisfaction surveys. How can you get closer to the truth, to determining real, actionable steps to drive customer behavior, when you don't know what they're thinking in the first place?

Behavior is truth

And there lies the real paradox: our actions are driven by emotion (in our irrational subconscious) much more than logic. Yet, to really understand your customers, you can't look at those emotions. Instead you must take a step back, stop making assumptions and focus on their behavior. Behavior, it turns out, leads to the truth.

Paco Underhill, a self-described "retail anthropologist," has understood this for a long time. In his book, Why We Buy, The Science of Shopping, he makes a compelling case for employing observation of customer behavior over other techniques like surveys. To help his clients get closer to the truth, he doesn't ask customers; instead he sends his "trackers" out in the field to the actual retail environments, and observes customer behavior in real time.

It was through this power of observation that Underhill discovered what he referred to as the "butt brush factor." He noticed that there were serious and unintended consequences when two product displays stood in close proximity to each other. If a customer wanted to bend down to take a closer look at a product on a lower shelf, it forced passersby to turn and shuffle by, resulting in said "butt brush." This seemed particularly uncomfortable for women, and it meant very low sales on the products in those displays. The behavior, in other words, held the answer to an actionable improvement to the customer experience, and to desired customer behavior.

Just think: if, instead of observing behavior, a retailer relied on the conscious or "logical" responses from its customers. Do you believe they would articulate the embarrassing "butt brush" as a factor in their behavior?

To improve the customer experience, look at the numbers

This same idea — that behavior is truth — holds in the online retail world as well. You can't just ask customers your website is "satisfactory," or what improvements they'd like to see. They don't know. The scientific findings over the last 20 years show just how ignorant we all are about our true feelings. So don't bother going down that road. To get to their hearts' desires, it's much more effective to devote your company's time and resources watching customers' actions, and not probing their feelings (ironic, isn't it?).

And that's actually pretty easy for your online environment. For most businesses, grabbing the Web tracking numbers is no longer brain surgery, and a large part of the customer story lies in those metrics. Can you see just what your customers are trying to do on your site? Where do they enter, and what path do they start down? Where are the road blocks? It's been our experience that, once you look at the behavior, it's not that hard to see where customers are abandoning the site, where they are stalling or backtracking, and more.

So remember, it's not what they say, it's what they do. Your customers don't know what they're thinking, but you know what they're doing, and there's power in that knowledge. So use it.

William Cusick is CEO and founder of Vox, Inc., a Chicago-based customer experience consulting firm. His new book is "All Customers Are Irrational: Understanding What They Think, What They Feel, and What Keeps Them Coming Back."