When we’re looking to change or improve something, it’s in our nature to add rather than subtract. That’s the conclusion of recent research titled People systematically overlook subtractive changes in the journal Nature.

Consider the Lego structure below — if presented with this structure and a pile of additional Lego blocks how would you change it so that it could support a masonry brick without crushing the little Lego dude?

The vast majority of people presented with this Lego problem added blocks under the roof to make it more stable while only a small percent chose to remove the one pillar support block so that the roof sat flush on the base. Even when participants were prompted to think of subtracting by being charged ten cents for each Lego added, only 41% solved the problem by removing the single support pillar.

The research went way beyond just Lego structures. Over a course of years, the researchers asked participants “to make changes to designs, essays, recipes, itineraries, structures and even miniature-golf holes.” In each experiment, the studies showed that people’s first instinct is to change things by adding. Source.

In his book Subtract, Leidy Klotz, one of the study authors, describes an experiment where the researchers asked participants to improve an itinerary for a day spent in Washington, D.C.:

Over the course of fourteen consecutive hours, this itinerary had the participants visiting the White House, Capitol Building, Washington National Cathedral, United States National Arboretum, the Old Post Office, and Ford’s Theatre; with additional stops to pay their respects at the Lincoln, World War II, and Vietnam Veterans Memorials; and, rounding out the itinerary, a museum visit, shopping, and lunch at a five-star bistro. Travel time alone between all these stops would exceed two hours, and that is before considering D.C. traffic. Participants saw this original itinerary in two sections: “Morning: 8:00 a.m.–3:00 p.m.” and “Afternoon/Evening: 3:00 p.m.–10:00 p.m.” Using a drag-and-drop interface, participants could change their itinerary by rearranging, adding, and subtracting activities. Only one in four participants removed activities from the packed original.

Solving problems or making improvements by subtracting rather than adding can provide benefits:

• Subtracting can lead to use of less resources which saves cost and can provide an environmental benefit. A good example of this the hollow brick invented by Anna Keichline in 1927. “Before Anna Keichline, building blocks were solid. Solid blocks built Mesopotamian homes, Rome’s Colosseum, Coba’s pyramid, and the Washington Monument. If your house is more than a century old, it probably rests on solid blocks. But, in her 1927 patent for the K-brick, Keichline subtracted that mass. Keichline the engineer knew that as long as the load-bearing outside parts of the blocks were solid, the insides could be hollow. And Keichline the architect knew that hollow blocks would appear exactly the same from the outside.” Source. By removing the inside of bricks, the cost of the bricks went down as did the weight, making them easier to handle and less costly to transport. Here’s a solid brick, an early K-brick and its modern manifestation:

• Subtracting can provide additional resources to be used elsewhere. “When we add to change a system, we are left with the improved system. But when we subtract to improve a system, we are left with the new-and-improved system, plus whatever we have taken away from the old one.” For example, the removed center of bricks can be used to make additional bricks and the dough removed from the center of doughnuts can make doughnut holes.

• A subtracting solution might be a better result than an adding one. Since learning of this research and reading Leidy Klotz’s book I’ve tried to include subtracting in brainstorming solutions. For example, recently we determined that one of our client teams is understaffed — there is just too much work for the four members of the team. Our first thought was “who should we add to the team?” But then we stopped and asked, “how can we subtract?” By asking this question we saw that a better solution was to reduce the workload of two of the team members on other client teams so they have more time to focus on the client at issue. That’s a better solution than adding because smaller teams tend to be more effective than larger ones. For more on that point, check out this IFOD: Why Throwing People At A Project Will Slow It Down

• Less can enhance to happiness. Subtracting can provide time which is a non-renewable resource. Research has found that spending money to save time — like spending money on services like cleaning, cooking, and household maintenance — leads to greater life satisfaction than money spent to buy tangible items. Source.

That humans default to adding rather than subtracting is a cognitive bias of which we should be aware. Instead of approaching a problem only by thinking of what we can add, we should also think about what we can subtract.