Why Strong Intentions Still Fail to Change Behavior

Why Strong Intentions Still Fail to Change Behavior

You decide to exercise three times a week. You buy the shoes, download the app, tell your friends. You mean it. You really mean it. And then, somehow, you don't do it.

This is the intention-behavior gap, and it is one of the most frustrating facts about being human. We want to change. We plan to change. We do not change. For decades, psychologists assumed the solution was simple: make your intentions stronger. Want it more. Commit harder. Be more certain.

Mark Conner and Paul Norman, two psychologists at the University of Leeds, spent years studying this assumption. Their 2022 paper in Frontiers in Psychology (Conner & Norman, 2022) arrives at a conclusion that is both intuitive and deeply unsettling: strong intentions do predict behavior better than weak ones. But the same features that make intentions strong also make them brittle, stubborn, and surprisingly resistant to the very interventions designed to strengthen them.

We have been thinking about willpower all wrong. The problem is not that your intentions are too weak. The problem is that strength itself has a dark side.

What Does It Mean for an Intention to Be "Strong"?

Conner and Norman define intention strength as having four distinct features. These features are not separate things. They feed into each other, forming a kind of psychological knot.

First, strong intentions are stable over time. You decide to exercise on Monday, and you still want to on Wednesday. This sounds obvious, but it is surprisingly rare. Most of us change our minds constantly without even noticing. A strong intention survives the week.

Second, strong intentions are pliable resistant to change. This sounds like the same thing as stability, but it is not. Stability means the intention does not change on its own. Pliability means it does not change when something tries to push it. If a friend invites you for drinks instead of the gym, a pliable intention stays put. A weak one folds.

Third, strong intentions bias information processing. Once you decide something firmly, your brain starts filtering reality to match that decision. You notice articles about the benefits of exercise. You forget studies about injury rates. Your intention becomes a lens, and everything you see confirms that you made the right choice.

Fourth, strong intentions predict behavior. This is the one everyone talks about. People with strong intentions actually do the thing more often.

But here is the twist. These features are not independent. They cluster together. And that clustering creates a paradox.

The Paradox of Strength

If you want to predict who will actually exercise, measure intention stability. A person whose intention stays constant over two weeks is far more likely to follow through than someone whose intention fluctuates. Conner and Norman argue that stability may be the most important single predictor of behavior (Conner & Norman, 2022).

But stability is hard to create. You cannot just tell someone to be more stable. You cannot inject stability like a vaccine. Stability emerges from the other features of strength: certainty, importance, and extremity.

Certainty means you are sure you will do it. Not hopeful. Not optimistic. Sure.

Importance means the behavior matters to your identity. You are not just trying to exercise. You are becoming someone who exercises.

Extremity means your intention is at the far end of the scale. Not "I kind of want to." Not "I intend to try." I absolutely intend to do this.

These three predictors of strength are what Conner and Norman call "moderators." They moderate the relationship between intention and behavior. If you score high on all three, your intention is strong. But here is the part that makes this research so interesting.

Strong Intentions Are Harder to Change

If you want someone to start exercising, you might try to increase their intention certainty. You give them information, testimonials, success stories. You try to make them more sure.

But people with already strong intentions are less responsive to this kind of intervention. Their intentions are pliable resistant. They have already decided. Their information processing is biased toward confirming their choice. They are not listening to you.

This means the people who most need their intentions strengthened are the least likely to respond to the standard tools of persuasion. And the people who already have strong intentions do not need strengthening at all. They just need to act.

Conner and Norman describe this as a fundamental asymmetry in the intention-behavior gap. Interventions that work on weak intentions may not work on strong ones. And interventions designed to strengthen intentions may only reach people who already have them.

The Study Behind the Idea

Conner and Norman's paper is a review, not a single experiment. They synthesized findings from dozens of studies on the intention-behavior gap, focusing on physical activity, diet, and health behaviors. The paper has been cited 418 times since 2022, which is a lot for a review in a specialty journal.

The authors drew on a tradition of research going back to Icek Ajzen's theory of planned behavior and the work of Paschal Sheeran, who first popularized the concept of the intention-behavior gap in the early 2000s. What Conner and Norman add is a systematic account of intention strength as a multidimensional construct.

They argue that most previous research treated intention strength as a single thing: how much you intend. But that misses the complexity. Two people can both say they intend to exercise, but one is certain, stable, and biased toward the behavior, while the other is uncertain, fluctuating, and open to alternatives. These two people are not in the same psychological state, even though they give the same survey response.

What They Measured

The studies Conner and Norman reviewed typically measured intention strength in two ways. First, they asked participants to rate their intentions on a scale: "I intend to exercise regularly over the next month" from 1 (strongly disagree) to 7 (strongly agree). Second, they measured the moderators: certainty, importance, and extremity.

Then they tracked actual behavior, usually through self-report or objective measures like accelerometers.

The consistent finding was that intention strength predicted behavior, but only when stability was high. People with strong but unstable intentions were not much better off than people with weak intentions. The stability mattered more than the initial strength.

The Stability Mechanism

Why does stability matter so much? Conner and Norman propose a mechanism. Stable intentions are more likely to be translated into concrete plans. If you intend to exercise on Monday, and you still intend to on Monday morning, you are more likely to have a plan for when, where, and how. You are more likely to have anticipated obstacles.

Unstable intentions, by contrast, never get the chance to become plans. They fade before the moment of action arrives.

This is why the paradox of pliability is so important. If you make someone's intention more certain, you also make it more stable. But you also make it more resistant to future change. That is fine if the intention is good. It is a disaster if the intention is bad.

What This Does Not Prove

Conner and Norman do not claim that strong intentions are always better. They are careful to note that the relationship between intention strength and behavior is nonlinear. At some point, making an intention stronger may not help. It may even hurt.

Consider the phenomenon of overconfidence. People who are extremely certain they will exercise often fail to anticipate obstacles. They do not plan for bad weather, fatigue, or competing priorities. They assume their intention is enough. And when the obstacle appears, they have no backup plan.

This is the dark side of information bias. If you are too certain, you stop processing information that might help you. You become blind to your own limitations.

The authors also note that most of the research has been correlational. We know that stability predicts behavior, but we do not know if increasing stability causes better behavior. The causal direction could be reversed. People who exercise regularly may develop stable intentions, not the other way around.

The Open Question

The biggest open question is how to strengthen intentions without making them brittle. Conner and Norman suggest that interventions should focus on stability directly, rather than on certainty or extremity. But we do not have good tools for that yet.

One possibility is implementation intentions: specific plans that specify when, where, and how you will act. "If it is 7 AM on Monday, I will go to the gym." These plans work by creating automatic triggers. They bypass the need for strong intentions altogether.

But implementation intentions have their own limitations. They work best for simple, discrete behaviors. They are less effective for complex, ongoing behaviors like maintaining a diet or managing a chronic condition.

What This Actually Means

The research from Conner and Norman does not tell you to give up on strong intentions. It tells you to be smarter about how you build them. Here is what that looks like in practice.

• ▸Stop trying to make yourself want it more. Wanting is not the bottleneck. The bottleneck is stability. Focus on keeping your intention alive across time. Check in with yourself daily. Reaffirm your commitment. Do not let the intention fade.

• ▸Be suspicious of certainty. Certainty feels good, but it can make you blind. Leave room for doubt. Plan for obstacles. Assume that something will go wrong and decide now what you will do when it does.

• ▸Do not change your mind lightly. If you intend to do something, treat that intention as a commitment. The more you let yourself reconsider, the more unstable your intentions become. Stability is built by refusing to reopen the decision.

• ▸Use implementation intentions to bypass the need for strength. If you cannot maintain a stable intention, do not try harder. Make a specific plan. Automate the decision. The goal is not to want it more. The goal is to do it without thinking.

• ▸Watch for the dark side of pliability. Strong intentions are hard to change. That is good if the intention serves you. It is dangerous if it does not. Be careful what you make yourself certain about. You might not be able to unmake it.

The intention-behavior gap is not a failure of will. It is a feature of how intentions work. They are not static things you possess. They are dynamic processes that need to be maintained, protected, and sometimes abandoned.

Conner and Norman's contribution is to show that strength is not a simple solution. It is a tradeoff. Strong intentions predict behavior better, but they also lock you in. They make you resistant to new information. They make you certain, and certainty is not always wisdom.

The best intentions are not the strongest. They are the most flexible. They are stable enough to survive the week, but pliable enough to change when the evidence demands it. That is a hard balance to strike. But it is the only one that works.