Why Do We Value Things More When We Made Them?

You spent three hours assembling a bookshelf from a flat-pack box.

The result is functional. It’s probably not perfectly level. The cam locks are slightly off. If someone offered to trade it for an identical bookshelf that came pre-assembled, you might refuse — or you might feel some genuine reluctance that you’d struggle to justify rationally.

This is not sentimentality. It’s a documented cognitive bias with a name, a mechanism, and implications that extend far beyond furniture.

The Norton Study

In 2012, Michael Norton, Daniel Mochon, and Dan Ariely published a series of experiments examining what they called the IKEA effect — named for the Swedish furniture company that popularized self-assembly products.

In the experiments, participants either assembled or received pre-assembled IKEA products (boxes and shelves), origami figures, or Lego structures. They then valued their creations by indicating how much they would pay for them.

The results: people consistently valued their own creations more highly than identical versions made by others. Participants who built their own boxes valued them 63% more than other participants valued the identical pre-built boxes.

Critically, the effect disappeared when participants couldn’t complete the assembly — people who built a partially assembled box and then had to dismantle it without finishing showed no extra attachment. The effort alone wasn’t sufficient. Completion was required.

The Effort Justification Root

The psychology behind the IKEA effect connects to older research on effort justification — the tendency to value outcomes more when we’ve worked harder for them.

Aronson and Mills showed in 1959 that participants who underwent a severe initiation (reading embarrassing material to join a group) rated the group as more interesting than participants who had an easy initiation — even though the group was identical and objectively mediocre. The harder you work to get something, the better you need to believe it is.

The cognitive mechanism: effort is costly. Investing effort in something that turns out to be worthless would mean you made an irrational choice. To avoid that conclusion, the mind adjusts the value upward to justify the cost.

This is a form of cognitive dissonance reduction: “I worked hard on this” creates pressure to believe “therefore it must be worth it.”

Labor as Self-Expression

Norton and colleagues also found that the IKEA effect depends on the object being seen as the product of one’s own creation — not just labor.

When participants made objects that someone else told them to make (following strict instructions with no creativity), the effect was weaker. When there was some element of choice or customization, even minor, the effect strengthened.

This points toward a second mechanism: self-expression. Objects we created feel like extensions of ourselves. They represent our choices, our taste, our decisions — even if those decisions were minor (which color peg, which configuration). Owning something you made is, in a small way, owning a piece of your own agency expressed in the world.

The valuation isn’t purely effort — it’s authorship.

Why This Matters Beyond Furniture

The IKEA effect helps explain a set of otherwise puzzling behaviors:

Why we like our own ideas more than other people’s. An idea you developed, refined, and worked through has your labor and authorship invested in it. This makes it genuinely harder to evaluate your own ideas fairly — not from arrogance, but from the same mechanism that makes you overvalue your bookshelf.

Why it’s hard to throw out things you made. Home-sewn clothes, sketches, early code, handmade gifts — things with labor and authorship attached to them persist long after their utility justifies it.

Why “DIY” businesses build loyalty. Customers who configure their own product (color, features, customization options) value it more than customers who receive a standard product. The labor of choosing is part of the value.

Why startups overvalue their MVPs. The first version of something you built with significant effort often feels more valuable than an outside evaluation would confirm. The effort has been invested; the valuation follows.

The Completion Requirement

The fact that incomplete assembly removed the effect is one of the study’s most interesting findings.

Effort that doesn’t produce an outcome doesn’t justify itself. Only completed effort generates the dissonance that requires upward valuation. This means the IKEA effect is specifically about completed creation — not about liking challenges, or valuing process, but about the particular attachment that comes from having made something that exists in the world.

Half-finished projects don’t generate the same attachment. In fact, incompletion often generates negative affect — the Zeigarnik effect, the nagging sense of the unfinished. The reward, and the inflated valuation, comes from closure.

Your bookshelf is probably fine. The cam locks are probably close enough.

And the slight warp in the bottom shelf is, in a specific and irrational way, yours.