Nudge and Sludge: The Vocabulary of Everyday Money Decisions

I'm Andy Temte and welcome to Money Lessons! Join me every Saturday morning for bite-sized lessons that are designed to improve financial literacy around the world. Today is September 5, 2026.

Last Saturday I told you we'd read a pay stub today, line by line. We'll do that next Saturday.

For three weeks we've taken apart the machinery that moves money out of your household without a decision anywhere in it — habits, defaults, and friction. I taught you how all three work and never gave you the words for them. Without the vocabulary, you can't name what you're looking at when you run into it, and you can't go read further on your own.

So today is the vocabulary. Five names, two books, and two terms.

Five Names and Two Books

In March of 2025, in an episode on cognitive bias, I introduced Daniel Kahneman, Amos Tversky, and Richard Thaler. Kahneman won the Nobel Prize in economics in 2002, for work he did with Tversky on how people make decisions when the outcome is uncertain. Thaler won the same prize in 2017. In that episode I also mentioned Thaler's book with the legal scholar Cass Sunstein — Nudge: Improving Decisions About Health, Wealth, and Happiness, published in 2008 — and Kahneman's Thinking, Fast and Slow, published in 2011.

Then I moved on and never came back to any of them.

Those two books sit underneath almost everything we've covered since the beginning of August. If you read one book about money and decision-making this year, make it one of those two. Neither one asks you to do any math.

The Perfect Information Problem

Before either book was written, Herbert Simon raised an objection to the way economists modeled human behavior. Simon wasn't an economist. He earned his doctorate in political science and spent fifty-two years at Carnegie Mellon teaching administration, psychology, and eventually computer science. In 1978 he won the Nobel Prize in economics anyway.

Accepted economic theory in Simon's era made sweeping assumptions about what buyers and sellers knew. The standard models assumed that a market participant had access to full information — every available option, every price, every consequence — because the mathematics required that assumption in order to work. Remove perfect information from those models and the equations stop producing clean answers.

Simon said the assumption of perfect information does not describe the real world. Nobody has unlimited time to search. Nobody has complete information. Nobody can trace every consequence of every option. What people do instead, Simon observed, is stop searching once they find an option that's good enough. He named the idea bounded rationality: decision-making that runs into limits.

One detail about Simon's research matters for what we've covered these last three weeks. Simon wasn't studying shoppers. His Nobel Prize was awarded for research into decision-making inside companies — he was watching managers. The imperfect information limits he identified turned up in boardrooms and purchasing departments years before anyone went looking for them in customers.

Choice Architecture

Richard Thaler gave a name to the way options get presented to you. He called it choice architecture, which put simply is the arrangement of the choices in front of you at the moment you decide.

Here, the word arrangement means how a transaction is organized. Which options appear on the screen in front of you, and which ones appear a level down? What order are they listed in? Which box arrives already checked? How many steps does each path take? Does the price show up next to the product, or at the end of checkout?

Both of the last two Saturdays were about choice architecture, and I never used the term. A retirement plan that enrolls you unless you decline is an arrangement — somebody decided that declining takes an action and enrolling doesn't. A saved card that turns a purchase into one tap, sitting next to a cancellation that takes six screens, is an arrangement — somebody decided how many steps each path would take.

Here is what makes the term worth knowing: no arrangement is neutral. Options have to appear in some order, and where an option sits in that order changes how often people pick it. A checkbox is either checked or unchecked when the page loads, and there's no third state. A cancellation link is either easy to find or it isn't. Whoever builds the page cannot decline to arrange it.

Copied, Not Designed

I want to be careful here, because it would be easy to leave this episode believing that every awkward form you've ever met was engineered by somebody at a whiteboard working out how to separate you from your money. Some were. Most were not.

Most businesses in this country are small, and small businesses don't employ behavioral economists. When a business opens an online store, the checkout sequence arrives with the off-the-shelf store software they decided to use. The cancellation policy gets copied from a competitor. The renewal terms come from whatever the rest of the industry does.

During my years in business, I watched small and mid-size company owners copy tactical operating practices from competitors and from larger firms. Sometimes out of convenience. More often because they lacked the resources to hire choice architects and pricing experts.

What the customer meets is an arrangement nobody designed on purpose, assembled out of parts that came from somewhere else.

Sludge

Some arrangements are deliberate, and Thaler named that too.

In 2018, ten years after Nudge came out, he published a one-page article in the journal Science titled "Nudge, Not Sludge." Sludge was his word for friction aimed at the person who has to get through it. He described two types of sludge. There's friction that blocks you from doing something in your own interest — claiming a rebate, collecting a tax credit, cancelling a service you no longer use. And there's friction that hurries you into something against your interest — a countdown clock, a limited-time offer, a box that arrives already checked.

Notice who gave us this new term. The economist who showed the world that arrangement changes behavior is the same one who, a decade later, published a warning about arrangement aimed at the customer. He closed that article by urging people to keep nudging for good and to start cleaning up sludge.

What This Means for You

You now have five names and two terms. Herbert Simon showed that nobody decides with complete information, and nobody has unlimited time to search for it. Kahneman and Tversky showed what the mind does when it's confronted with limited time and imperfect information — it takes shortcuts, and the shortcuts are predictable. Thaler and Sunstein showed what happens when somebody else controls how your options get presented to you. Choice architecture is that presentation: the order the options appear in, the box that arrives already checked, the number of steps each path takes. Sludge is that presentation built against your interest.

Next Saturday, your pay stub — and not a tour of the obvious lines. I want to spend the time on what most people skip past: what the gap between your gross pay and your take-home is made of, which deductions you chose and which ones you never had a say in, and the pay and benefit elections sitting in there that people leave unclaimed year after year without knowing they were available. That's the first of the six jobs your money has, and the one that starts everything else.

Until next week... Grace. Dignity. Compassion.