88 out of 90 people fall for this bias. Do you?

Summary

Podcast Summary: Nudge, Episode 88 – "88 out of 90 people fall for this bias. Do you?"
Host: Phill Agnew
Guest: Prof. Leidy Klotz (University of Virginia, author of Subtract)
Date: July 13, 2026

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Overview

In this episode of Nudge, Phill Agnew explores a pervasive human bias: the tendency to solve problems through addition rather than subtraction. Featuring Leidy Klotz, author of Subtract, and incorporating insights from Richard Shotten and Todd Rogers, the episode delves into real-world examples and scientific studies showing that "doing less" or removing elements can often be the key to improvement—especially in marketing, design, and communication.

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Key Discussion Points & Insights

1. The Lego Bridge Problem – Why We Default to Addition

[00:03]–[01:56]

• Phill Agnew opens with a thought experiment: given a crooked Lego bridge with three blocks on one side and two on the other, most people instinctively solve it by adding blocks rather than subtracting.
  • “Most of us, most adults at least, immediately think about addition.” [01:11]
• Leidy Klotz observes this with his own son and in studies: when presented with the bridge, 88% add blocks; only 12% subtract.
  • “When we're presented with a situation... our first instinct to try to make it better is to add something to it.” – Leidy Klotz [01:40]

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2. Subtraction in Everyday Life – From Cooking to Marketing

[02:58]–[04:26]

• This "additive bias" appears in various domains:
  • Cooking: In a soup experiment, 88 of 90 participants added ingredients to improve flavor instead of removing any.
    • "We were doing it for ingredients in soup and asking people to make this better. And yeah, people definitely added." – Leidy [03:23]
  • Pop culture reference to The Bear: professional chefs emphasizing subtraction.
    • “What the fuck is this shit? It’s way too many components. Basically made nachos. You want to add another fucking sauce?” – Chef (clip from The Bear) [04:08]
  • Marketing: More features or messages often harm rather than enhance persuasion.

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3. Specialization, Quality Perception, and the Goal Dilution Effect

[04:34]–[07:46]

• Richard Shotten recounts how Five Guys’ success was built on subtraction: focusing the menu solely on burgers and fries increased perceived quality.
  • “We have this idea, we have this assumption that those who specialise are higher quality.” – Richard Shotten [04:34]
• Goal Dilution Effect: More benefits/message points dilute the perceived efficacy.
  • Study: When told tomatoes prevent both cancer and eye degeneration (vs. just cancer), people rate them 12% less effective at preventing cancer.
    • “People rated eating tomatoes as 12% more effective at preventing cancer when this was given as the only benefit compared to it being listed alongside with another benefit.” – Phill Agnew [07:46]
  • “...if you add on extra reasons about why a vegetable is super healthy... they actually reduce it. Because people have a rule of thumb that we can't be all things to all people...” – Richard Shotten [08:14]

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4. Subtraction Gives a Competitive Edge

[08:49]–[09:26]

• Leidy Klotz: Brands that embrace subtraction have access to unexploited opportunities.

  • “If people are systematically overlooking a whole class of options, if you can think of that class of options, you’re going to be exploiting this inefficiency... you have a huge advantage.” – Leidy Klotz [09:02]

• Case Studies:

  • Companies like Nike, Adidas overload their messages with benefits—making each one feel less credible.
  • Suggestion: Focus on a single, sharp message for more persuasive impact.

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5. AI and the Additive Bias

[11:48]–[12:52]

• Studies show that AI also exhibits this additive bias, compounding the problem when humans and machines collaborate.
  • “AI does the exact same thing as humans. So AI has this additive bias and that can be kind of like a multiplicative effect...” – Leidy Klotz [11:48]
• Example: When using AI to write marketing copy or persuasive emails, both the human and the machine tend toward longer, more complex messages.
• But research (see below) proves the opposite is more effective.

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6. The Power of Shorter Messages – Todd Rogers’ Email Study

[12:52]–[14:49]

• Todd Rogers ran a study on email effectiveness among 7,000 school board members.

  • Two conditions: a wordy, deferential email vs. a concise, to-the-point message.

  • “Almost Everybody, literally, like 93%... are like, oh, obviously the longer one... will be more effective.” – Todd Rogers [13:24]

  • Actual results: Simple message doubled the response rate (4.8% vs 2.7%).

    • “...Deleting all the extra content made people more than twice as likely to respond and complete our survey, despite almost everybody thinking the opposite.” – Todd Rogers [14:25]

  • Enduring lesson echoed by writers and teachers:

    • “…the most assign in the US on college syllabi is Strunk in White’s Elements of Style... omit needless words. And yet it’s so hard, so hard to do.” – Leidy Klotz [14:49]

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7. Stress, Distraction, and the Bias Toward Addition

[15:05]–[16:08]

• Stress or cognitive overload makes the addition bias worse.
  • “When people were mentally distracted, they were even more likely to rely on the additive solution....when you're overwhelmed, you are less likely to subtract.” – Leidy Klotz [15:13]

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8. The Broader Value of Subtraction

[16:18]–[16:56]

• Subtraction opens up overlooked solutions, reduces clutter, aids focus, and allows for higher impact.
  • “It's really, you're just opening yourself to a whole other world of opportunities... Those are some of the kind of the general benefits of subtracting, but I think the overarching one is just a whole set of solutions that you may not have otherwise considered.” – Leidy Klotz [16:18]

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Notable Quotes & Memorable Moments

• Leidy Klotz:

  • “When we're presented with a situation... our first instinct...is to add something.” [01:40]
  • “AI does the exact same thing as humans. So AI has this additive bias and that can be kind of like a multiplicative effect...” [11:48]
  • “It's really, you're just opening yourself to a whole other world of opportunities...” [16:18]

• Richard Shotten:

  • “Those who specialise are higher quality...” [04:34]
  • “If you give people multiple reasons, rather than those additional reasons adding... they actually reduce it.” [08:14]

• Todd Rogers:

  • “Deleting all the extra content made people more than twice as likely to respond and complete our survey, despite almost everybody thinking the opposite.” [14:25]

• Phill Agnew (host):

  • “In life, less is often more.” [16:56 closing takeaway]

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Main Takeaways

1. Humans have a deep, unconscious bias to add rather than subtract when faced with problems—this shapes our work, creativity, and persuasion.
2. Subtraction is rarely considered—in Leidy Klotz’s studies, only ~12% of people solved problems by removing elements rather than adding.
3. More is (often) less: In communicating benefits, focusing on one sharp point is more persuasive than listing many (goal dilution effect).
4. Case studies: Subtraction in branding (e.g., Five Guys), product messaging, and copywriting leads to greater perceived quality and engagement.
5. AI tends to amplify the additive bias: Collaboration with AI tools usually produces even longer, more complex outputs—despite evidence that conciseness wins.
6. Embrace subtraction for a strategic edge: Brands and individuals who break the instinct to add can claim overlooked ground and simplify their work for better results.

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Timestamps for Key Segments

• [00:03] Lego bridge introduction – additive bias in problem-solving
• [01:40] Leidy Klotz’s research: why we add, not subtract
• [03:23] Cooking/soup experiment – additive bias in the kitchen
• [04:34] Specialization vs. generalization – Five Guys example
• [06:34] Tomato study – goal dilution effect explained
• [09:02] Competitive advantage of subtraction in business
• [11:48] Subtraction bias in AI-generated outputs
• [12:52] Todd Rogers’ email study – concise beats wordy communication
• [14:49] Classic writing advice: omit needless words
• [15:05] Stress/distraction makes us add even more
• [16:18] General value of subtracting—offers new solutions, reduces clutter
• [16:56] Closing: embrace subtraction; less is more

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Final Takeaway:
If you want to stand out—whether in marketing, communication, or creative problem-solving—remember: subtraction is a rare but powerful strategy. Doing less, saying less, and focusing more almost always wins.

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Transcript

[A]

In front of me right now, I have a Lego bridge. The bridge is, is very simple. This is not a complex piece of Lego. There are two long pieces connected together that form the bridge span. That's where the, the drivers and the pedestrians would drive and walk across. And then there are columns on either side of the bridge to form the foundations, the foundations that lifted above the river below. However, on the left side of the foundation, I have three pieces stacked on top of each other. On the right side, it is just two pieces stacked on top. My goal is to make the bridge level. How should I do it? Ask yourself, what would you do? You've got three pieces on one side, two on the other. What do you do to make the bridge level? You've got a pile of other Legos sitting next to you. What do you do? This exact problem inspired today's guest on Nudge to write his critically acclaimed book.

[B]

This is the basic issue that we had with my 3 year old son at the time. And it's like, how do we make this bridge level? And of course, I turned around behind me to grab a block to add to the shorter column, and by the time I had turned around, he had removed a block from the longer column.

[A]

Most of us, most adults at least, immediately think about addition. We think about how we should add a block to fix the problem. My guess is that most of you thought the same way when we introduced the problem at the start of the show. Because today's guest on Nudge has studied this exact scenario alongside his three colleagues, he recruited participants and gave them a slightly bigger bridge. It had eight or 10 blocks at the base. When asked to balance the bridge, 88% added a block. Only 12% removed a block.

[B]

When we're presented with a situation, whether it's a Lego bridge or an essay or a podcast episode or, you know, your calendar, our first instinct to try to make it better is to add something to it.

[A]

But often addition doesn't make something better. In many cases, especially in marketing and especially in business, it makes your offering worse. We'll explain how in today's episode of Nudge. Here's something that's happened to me a lot in using AI over the past couple of years. I've spent, you know, 20 minutes writing the perfect prompt. The output looks pretty good. It sounds, you know, authoritative, but it completely misses the point. That is what you get when AI doesn't have a clue about your business. HubSpot's AI works off your actual customer data. It looks at every interaction, every signal. Your team has built up over time. So rather than just prompt and cross your fingers and then start again with HubSpot, you can ask just once and get a great results. So check out HubSpot.com, the agentic customer platform for growing businesses. Hello and welcome. You are listening to Nudge with me, Phil Agnew. And I'm delighted to be joined again by the award winning professor and acclaimed author, Lydy Koltz.

[B]

My official job is as a professor in this department of Engineering and society at the University of Virginia.

[A]

While teaching at Virginia, Leidy wrote Subtract. The book presents a simple Humans have a tendency to add rather than take away. He first noticed this with his son building Lego bridges. And Liddy then studied this Lego scenario. But he didn't stop there. He tested the same human desire to subtract with cooking.

[B]

We were doing it for ingredients in soup and asking people to make this better. And yeah, people definitely added.

[A]

Specifically, they asked 90 participants to improve a five ingredient soup. 88 of those 90 participants added ingredients. Only two chose to remove ingredients to improve food. We assume that more is better.

[B]

There's an episode of the Bear, which is a cooking show in the US that people will send me clips of because there's a comment where like the head chef comes around and the new chef is putting things in and the head chef gets like really mad at them about adding too many ingredients and then puts a sticky note that says subtract.

[C]

What the fuck is this shit? It's way too many components. Basically made nachos. You want to add another fucking sauce?

[A]

Anybody got any more sauce we can add to this?

[D]

We already have a dish with dill in it.

[C]

You knew that, right?

[B]

Yes, Chef. Never repeat ingredients. Move on. So, yes, it happens in cooking.

[A]

So we have this tendency to add. And yet if you're trying to persuade or convince, adding is often the worst thing you can do.

[C]

We have this idea, we have this assumption that those who specialise are higher quality.

[A]

That's a previous guest on Nudge. He detailed how subtraction can often improve your marketing. He argues not to generalize and do many, many things, but instead to specialise and just do some things very well.

[C]

My name's Richard shorten and I specialise in applying behavioural science to marketing.

[A]

Richard told me in a previous episode of Nudge how one of the world's fastest growing fast food brands succeeded because they took on Lidi's advice and subtracted from their offering.

[C]

And there's this fascinating story about this guy called Jerry Murrell. He gives his sons an offer. I'll either pay for you to go to college or I'll give you some cash to set up a business. And they decide that they're going to set up a business and forego college. Merle decides this is going to be the kind of key focus of his brand. He sets up his restaurant with his four sons. So straightforwardly enough, he calls it five guys. And he just offers a very, very short menu. It's basically burgers and fries. He doesn't have to begin with yogurts and salads and chicken. He specializes in one area. Now, from a kind of, I don't know, economic or logistical point of view, there are benefits to doing that. But what's really interesting is there is also a psychological benefit. Now, let's say there's an alternative universe where there's five guys and there's six guys and their competitors, and five guys do brilliant burgers, nine out of ten. And six guys do brilliant burgers, and they score nine out of ten in terms of taste. Well, if six guys offer pizza and chicken and Chinese, even if the physical quality of their offering is just as amazing as five guys, people will not perceive it that way. We have this idea, we have this assumption that those who specialize are higher quality.

[A]

Richard has evidence to prove this, Specifically a study on the goal dilution effect.

[C]

Now, that's not speculation. You mentioned this idea of the gold dilution effect. So that's a study back from 2007 by Zhang and Fischbach, the University of Chicago. And they did this beautifully simple study. They recruit a group of people and then they split them into two subgroups. And half the people hear about the benefits of tomatoes. So you eat tomatoes and you have a reduced cancer risk. And those people are then asked, how good is tomato consumption at reducing cancer? They get their answer. They then get a new group, the second subgroup. They give them the same paragraph about cancer prevention, but then at the end, they add on a bit about tomatoes being good for stopping the degeneration of the eye.

[A]

So the first group is told of one benefit of eating tomatoes, and the second group is told about two benefits you'll get if you eat tomatoes.

[C]

That second group are then asked about, how good are tomatoes at preventing cancer? And even though they have exactly the same information regarding cancer, they score it about 12, 13% lower.

[A]

This is totally irrational. People rated eating tomatoes as 12% more effective at preventing cancer when this was given as the only benefit compared to it being listed alongside with another benefit. It's not logical, but we are more confident when just one advantage is presented. To Zhang and Fischbach, this suggested that conveying one clear benefit is simply just more persuasive. Adding multiple benefits seems to dilute credibility.

[C]

So the point here is if you add on extra reasons about why a vegetable is super healthy or a burger joint is really tasty, if you give people multiple reasons, rather than those additional reasons adding to the appeal or the believability of the offering, they actually reduce it. Because people have a rule of thumb that we can't be all things to all people, that a jack of all trades is a master of none. And once we have this rule in our head, we apply it even in situations where it's probably not appropriate.

[A]

Subtracting can make our offer, our service and our product appear to be better quality, and yet so few people and brands do it. In fact, it's so uncommon that subtraction can really give you a competitive advantage.

[B]

The biggest benefit of this is that just in the marketplace of ideas, right, if people are systematically overlooking a whole class of options, if you can think of that class of options, you're going to be exploiting this inefficiency that less people are thinking of subtracting to make this thing better. And if you can be the first one that does it, then you have a huge advantage.

[A]

Zhang and Fischbach covered more of that advantage in their study. In follow up experiments, participants saw messages promoting cardio exercise running. For example, half were told, cardio exercise helps protect you from heart disease. The other half were told, not only does cardio exercise protect you from heart disease, but it also helps maintain healthy bones. The 97 participants on average thought that cardio exercise was less effective when they heard about the two goals, heart disease and healthy bones. Subtracting makes cardio seem better for you, but most brands ignore this. I went to Nike's website and looked at a blog they had written about why running is good for you, and they list seven reasons. Adidas, Asics, they all do the same. But after the break, Leidy explains how Nike could use subtraction to become more competitive. Science of Scaling, hosted by Mark Roberge, is brought to you by the HubSpot Podcast Network, the audio destination for business professionals. In each episode, Mark, a senior lecturer at Harvard Business School, sits down with the most successful sales leaders in tech to learn the secret strategies and tactics to scaling your company's growth. It's a fantastic show, so go and listen to the science of Scaling wherever you get your podcasts. Late payments are One of the most frustrating parts of running a small business. Chasing invoices can take time, and without the right support, it's easy to let invoices slide. The Federation of Small Businesses have recovered over 6 million pounds for small businesses and they give you free template letters step by step, guidance and specialist support to get your cash flow back on track. It's one of the reasons I joined in the first place. And honestly, it's one of the benefits I probably use the most. Visit get.fsb.orguknudge or click the link in the show notes and use code nudge to get 10% off your membership. Hello, welcome back. You're listening to Nudge with me, Phil Agnew. So far, Lady Koltz has covered how humans have a natural bias for addition. We like to add rather than remove. However, we've also heard from Richard Shotten, who shared how addition can dilute our offering. If we want to persuade, we should say less rather than more. Because of this, Lidi shared that merely subtracting from your ideas can give you a competitive advantage. And Lidi says this is even more important in a world where many are using AI.

[B]

People have replicated our subtraction studies with AI, and the AI does the exact same thing as humans. So AI has this additive bias and that can be kind of like a multiplicative effect, right? Where it's like you've got the tool itself has this additive bias and then it's multiplied by the human's additive bias and you are getting even more of this problem.

[A]

Say you're writing an email designed at persuading someone. Perhaps you're writing an email persuading someone to buy your product or someone to join your company, or someone to come to your event. Naturally, you will feel a tendency to write more, to say more. If you use AI, it will attempt to do the same, to add more and more and more. And yet study after study shows that writing more is less effective. A few years back, I spoke to the Harvard professor Todd Rogers about this very topic. He's run one of these studies which showcases how adding more isn't best. He's proved that adding words to your email will not make that email more persuasive. Here's Todd.

[D]

Sure. So we scraped 7,000 email addresses of elected school board members in the United States, and we were going to email them, asking them to fill out a survey about important decisions they were making during the pandemic. And the actual first draft that we wrote was, I'm a professor, I'd like to ask you some questions. I know what you do is important. I know you're very busy. I know that you're serving lots of others. Thank you for everything you're doing. It's a very hard job you have. You're balancing competing interests and like, maybe six or seven sentences of just gratitude and appreciation and recognition. And then it ends by. Please click this link to fill out our survey. The other condition, which was just a suggestion someone had during our development of this message, they're like, well, what if we just said, I'm a professor, I'd like to ask you some questions. You're doing important work. Will you please fill out the survey? So just reduce the words by two thirds before running the experiment. We actually have people predict which of these two do they think will be more effective. And people read both. And almost Everybody, literally, like 93% of people reading both are like, oh, obviously the longer one that is more deferential and expresses more gratitude will be more effective. So we run the experiment. More than twice as effective is the one that is much shorter. Deleting all the extra content made people more than twice as likely to respond and complete our survey, despite almost everybody thinking the opposite.

[A]

One of Todd's emails had 127 words. The other had just 49 words. Despite the majority of people thinking the wordier email would perform better, Todd found the concise email was far more effective. It yielded nearly twice as many survey responses as the wordy email. That's a 4.8 response rate compared to just 2.7%.

[B]

I mean, the most assign in the US on college syllabi is Strunk in White's Elements of Style. And like, one of the core pieces of advice in that is omit needless words. Right? I mean, we've all been told this, and yet it's so hard, so hard to do.

[A]

Often saying less is more. And yet, like Leidy says, it is very hard to do, especially when we're stressed and have limited time to think.

[B]

Yeah, we gave participants in our studies one of the subtracting tasks was like random grids on a computer screen, and you had to make them symmetrical from left to right and top, bottom. And one of the ways to do it was the. The right way to do it was to subtract blocks to make the pattern symmetrical. What most people would do is add the blocks and then we would. There was a version of that study where while they were trying to solve the problem, they would also have, like, a scroll of numbers going across the bottom of the screen. And every time a five went by, they had to press an F on their. So it's like you're texting and driving. Basically, you're mentally distracted. And when people were mentally distracted, they were even more likely to rely on the additive solution. So again, that was for our research. It was to show that, okay, this seems like it's like a heuristic, but for the rest of life. It shows that when you're overwhelmed, you're even less likely to look for this type of solution.

[A]

When you're stressed and overwhelmed, you are less likely to subtract. But as Lydie, Richard and Todd have each shared, subtracting tends to make the thing you're working on better.

[B]

It's really, you're just opening yourself to a whole other world of opportunities, right? This whole class of solutions that you otherwise may not think of. And then the benefits, you know, it ties into having less clutter in your physical world, having less clutter in your mind, and being able to focus on things that really matter, having more time in your schedule. Like, those are some of the kind of the general benefits of subtracting, But I think the overarching one is just a whole set of solutions that you may not have otherwise considered. No matter what the problem is subtraction,

[A]

most of us don't do it. When presented with the lego Bridge, only 12% removed bricks and only two participants removed ingredients from that soup recipe. Yet subtracting can often make things better. It made five guys more popular, can make cardio seem more effective, tomatoes a better health food, and makes a newsletter more likely to generate donations. If there is one takeaway from today's episode of Nudge, it is this. In life, less is often more. Well, thank you so much for listening to today's episode of Nudge, folks. And thank you again for the brilliant Lidi for joining me on today's show. If you've liked today's episode, you will love this book, subtract. It is critically acclaimed. I think it's award winning. It's well worth the read. It's easy to read and still very relevant despite being written in 2021. So if you want to read that, go and pick up a copy. There's a link to it in the show notes. Before ending today's show, I want to say another thank you to the Federation of Small Businesses. They have sponsored today's episode. And as I mentioned in the advert I did in the middle of the show, I'm a member of the FSB and I'M a member and I signed up with my own money before they sponsored the show, so I'm really happy to have them as a sponsor because I think they're a really important asset for small businesses. I signed up to them because I run a small business that really benefits from their support. As a member, I get stuff like members only discounts, which have saved me hundreds of pounds on my subscription products. I'm in a community of 500,000 other businesses, so I can get really good advice but also really good training as well. From everything to making tax digital to really marketing advice as well. But more importantly, I get legal advice. This is really important. If I'm ever in legal trouble, they're able to cover my legal fees. I get £100,000 worth of COVID for things like tax, investigation, protection, and I even get help with recovering debt from clients who haven't paid their invoices. As I have no employees, I pay just £195 per year for this subscription and I have made that back already in just the discounts alone. But if I ever have any problems, legal problems or problems like that, It'll be worth 10 times, even 100 times more than that. So thank you again to the FSB for supporting today's show. As a reminder, they've kindly agreed to give out a 10% discount to nudge listeners. They don't really do discount codes, so this is a genuinely good deal. To get that, click the link in the show notes and use the code nudge at checkout. So please do go and become a member of the FSB today if you run your own small business. Thanks again. I'll be back on Nudge next Monday for another episode. Thank you so much for listening. Cheers.