I came across the Consistency Principle years ago, without knowing it, when reading about sales techniques.

It was embedded in the method used — ingeniously in its time — by Encyclopedia Britannica door-to-door sales reps. When someone came to the door, they would ask a series of questions that elicited a “yes”: “Do you live here?” “Do you have children?” “Do you want them to do well in school?” … ultimately leading to “Are you ready to invest in your child’s success?”

This stuff goes on all around us today. Here’s what you need to know to protect yourself.

Why Your Brain Loves Consistency

Our brains automatically default to being consistent. It’s a shortcut they use, to avoid thinking too hard about making individual decisions. That way, we can save our brainpower for tougher work.

Once we decide we like something — such as Portillo’s chocolate cake (had too much of that over the holidays) — we don’t have to spend time considering this when someone asks if we want it.

This is why we often say “yes” to something without thinking, and then immediately wish we hadn’t. But we follow through, no matter how we now feel, because we want to be consistent with our word.

No: we don’t want to turn off all automatic drives for consistency. Our brains really don’t have the bandwidth to give equal time to each of the decisions we make every day.

How can we 1) see when this is happening and 2) protect ourselves from those who understand the Consistency Principle and use it to flim-flam us?

Watch for Two “Tells”

In his book Influence: The Psychology of Persuasion, Robert Cialdini offers two suggestions.

First, notice that sinking feeling in the pit of your stomach. It’s that tightening or churning you feel when you’ve just committed to doing something you know you don’t want to or shouldn’t.

We make decisions in our emotional brain, and then back and fill with our logical brain. That means we experience our feelings before our thoughts. These often show up in our bodies: in this case, our stomachs. Pay attention.

Second, answer an important question. Often we’re taken by surprise. We didn’t expect the lead-up conversation/interaction to bring us to a choice that now gives us the gut clench.

It’s time to answer, “Knowing what I know now, if I could go back in time, would I make the same decision?”

Cialdini says this taps into another part of your body: your heart of hearts. If your answer is “yes,” then this is good consistency. If “no,” then don’t feel bound to do it.

Don’t Get Comfortable with Discomfort

When you realize someone is using the Consistency Principle against your will, you’ll feel uncomfortable. You may already have agreed, and don’t want to look indecisive or like a jerk.

Remember: often these people are trying to manipulate you into doing something against your better judgment. Now that you know this is their game — and they haven’t been straight with you in getting your agreement — don’t feel bound to follow through.

You may choose to explain why you’re not going to comply, or call them on what they’ve done.

With that door-to-door sales person: “I understand what’s happened here. It’s your job to sell encyclopedias. And your process is to get me into a pattern of saying ‘yes’ without much thought, so I’ll agree to buy the set, and then be embarrassed to appear to change my mind. But the truth is I don’t need this for my children. Thanks for your time and good luck.”

Over 175 years ago, the American writer Ralph Waldo Emerson said, “A foolish consistency is the hobgoblin of little minds.” Make sure yours is intentional. It will save some wear and tear on your stomach and heart.