Why is it significant for students to use think-addition for subtraction rather than take-away?

Consider the following questions: Do your resolutions more often start with “I should do more of . . .” than with “I should do less of . . .”? Do you spend more time acquiring information—whether through podcasts, websites, or conversation—than you spend distilling what you already know?

How about: Do you add new rules in your household or workplace more often than you take rules away? Have you started more organizations, initiatives, and activities than you have phased out? Do you think more about providing for the disadvantaged than about removing unearned privilege?

And: Do you have more stuff than you used to? Are you busier today than you were three years ago?

If you answered yes to any of these questions, you’re not alone. In our striving to improve our lives, our work, and our society, we overwhelmingly add.

In each of these situations, we’re all doing essentially the same thing—trying to change things from how they are to how we want them to be. And in this ubiquitous act of change, one option is always to add to what exists, be it objects, ideas, or social systems. Another option is to subtract from what is already there.

Subtraction is the act of getting to less, but it is not the same as doing less. In fact, getting to less often means doing, or at least thinking, more.

An epiphany in my thinking about less came when my son Ezra and I were building a bridge out of Legos. Because the support towers were different heights, we couldn’t span them, so I reached behind me to grab a block to add to the shorter tower. As I turned back toward the soon-to-be bridge, three-year-old Ezra was removing a block from the taller tower. My impulse had been to add to the short support, and in that moment, I realized it was wrong: taking away from the tall support was a faster and more efficient way to create a level bridge.

In our striving to improve our lives, our work, and our society, we overwhelmingly add. We overlook the option to subtract from what is already there.

Since I had become a professor, I had been trying to convert my interest in less into something I could study instead of just ponder. From the start, I studied ways that buildings and cities might use less energy—and therefore produce fewer climate-changing emissions. I studied architecture and urban design, the people using it, and the people designing it. Over time, I had homed in on the designers, finding that, even when it leads to suboptimal things, designers use mental shortcuts: anchoring on irrelevant numbers, unthinkingly accepting default choices, and being swayed by examples. Still, I could never quite get from studying buildings and cities to studying less itself.

Ezra’s encounter with Legos took my applied thinking about design to a more basic level. Here, right in my living room, was a relatively simple situation that could be changed by adding to it and by taking away from it. And when Ezra’s choice caught me by surprise, it made me realize that, whereas less is an end state, subtracting is the act of getting there.

Not only did Ezra’s bridge shift my focus from less to subtraction, it gave me a convincing way to share and test my epiphany. So I began carrying around a replica of Ezra’s bridge. I tried it out on unsuspecting students who came to meet with me, checking whether they would subtract, like Ezra, or add, like I had. All the students added.

I also brought the Lego bridge to meetings with professors and one of them was Gabrielle Adams. Because of her intellect and because of our prior conversations about less, I suspected Gabe might see right through the bridge challenge. But she was like the others, and like me. She added a block to the shorter column to make the bridge.

Subtraction is the act of getting to less, but it is not the same as doing less. In fact, getting to less often means doing, or at least thinking, more.

Excitedly, I told Gabe how Ezra had removed a block—and that’s when it clicked for her. Her response gave me the language to bring countless others up to speed. She said, “Oh. So, you’re wondering whether we neglect subtraction as a way to change things?”

That sounded right to me.

Once Gabe figured out the question I was asking, she was on board, and she convinced Ben Converse, another psychology and public policy professor, to join us. Our first studies used Legos. 

In one study, recently published in Nature, we challenged participants to modify a sandwich-like structure made from Legos so that it was strong enough and high enough to hold a masonry brick above the head of a stormtrooper figurine. Each participant received a structure consisting of parallel horizontal Lego panels connected by a vertical column that narrowed to only one block wide where it connected to the top panel. We asked participants to:

“Improve this project so that it can hold a brick above the storm trooper’s head without collapsing.”

And we offered an incentive:

“You will earn one dollar if you successfully complete this task. Each piece you add costs ten cents.”

The best solution is to remove the single block forming the thin part of the column. The top panel can then be attached to the larger section of the column, which stabilizes the structure and still leaves enough clearance to avoid the storm trooper getting squashed by the masonry brick.

The problem is that we neglect subtraction. Compared to changes that add, those that subtract are harder to think of. Even when we do manage to think of it, subtracting can be harder to implement. 

Subtracting one block was the fastest way to solve the problem. Plus, only subtracting allowed participants to earn the full dollar.

And yet participants were still more likely to add than subtract. This was evidence that people add to their detriment—at least when trying to modify a Lego structure so that it can hold a brick safely above the head of a stormtrooper.

To try to override the greater accessibility of adding, we also gave some participants subtle reminders, or cues, that subtraction was an option. If those who received the cue subtracted more often, then that would indicate that those who didn’t receive the cue were overlooking subtraction.

The experimenter said to all participants, “You will earn one dollar if you successfully complete this task. Each piece that you add costs ten cents.” Participants randomly assigned to the cue condition heard one more instruction from the experimenter: “but removing pieces is free and costs nothing.”

In the no-cue group, 41 percent subtracted a block. In the cue group, 61 percent subtracted. Those who were cued took home an average of eighty-eight cents, 10 percent more than those who didn’t get the cue. The simple and subtle eight-word cue showed people a profitable solution that they had otherwise been missing. It sure seemed like people who didn’t receive the cue were missing the subtractive option not by choice but because they couldn’t see it.

The problem is that we neglect subtraction. Compared to changes that add, those that subtract are harder to think of. Even when we do manage to think of it, subtracting can be harder to implement. 

But we have a choice. We don’t have to let this oversight go on taking its toll on our cities, our institutions, and our minds. And, make no mistake, overlooking an entire category of change takes a toll.

Neglecting subtraction is harmful in our households, which now commonly contain more than a quarter of a million items. Someone has to organize and keep track of all those juicers, ill-fitting clothes, Legos, and everything else we’ve accumulated. That’s a lot to pay for and to think about, and it represents a lot of our time, time that is only getting scarcer, especially when we overlook subtraction as a way to relieve our obviously overbooked schedules. We neglect subtraction in our institutions. In our governments and in our families, we default to adding requirements. Ezra gets more and more rules, and grown-ups deal with federal regulations that are twenty times as long as they were in 1950. Too many rules and too much red tape can distract from the behaviors we’re really hoping for.

Whenever we try to change how things are to how we want them to be, we often overlook subtraction. And until we do something about it, we’re missing ways to make our lives more fulfilling, our institutions more effective, and our planet more livable. 

Adapted from Subtract: The Untapped Science of Less by Leidy Klotz. Copyright (c) 2021 by Leidy Klotz. Used with permission from the publisher Flatiron Books. All rights reserved.

Disclosure: Leidy Klotz co-directs the Covergent Behavioral Science Initiative at the University of Virginia, which is a 2021 Supporting Partner of Behavioral Scientist. Evan Nesterak, of the Behavioral Scientist, served as an editorial consultant on Subtract.