The story is about Betty Crocker Instant Cake Mix. Most of us are familiar with the stuff. Bought in a box at the grocery store, all it requires is the addition of oil, water and an egg. Mix then bake. Viola! Let them eat cake!

This seemingly simple process is the result of a lot of customer insights and user testing. When the product was first released, the preparation process was actually simpler. The mix contained dehydrated egg and oil, and the user (usually a homemaker) only had to add water. The cake tasted exactly the same, but what the Betty Crocker company saw unimpressive sales and a product category that wasn’t growing. They eventually discovered that these homemakers didn’t feel like they’d baked. It was too easy, and they weren’t proud of the result.

So they turned to user testing . During these tests, they varied the amount of ingredients the study participant was required to add. Some just added water, some water and an egg, some more. Then they interviewed them about how satisfied they were with the result. Keep in mind that every cake, regardless of the ingredients required of the participant, tasted exactly the same.

The result led to the formula we all know today. When the participants were asked to add water, oil and an egg, they felt like the cake was theirs. They felt like they’d baked. They were proud of their creation and continued to come back for more.

When there were fewer ingredients, it was too easy and they didn’t come back. When they were asked to add more ingredients, it was too much work and they didn’t want to do it again. The sweet spot was water, oil and an egg. And millions of cakes later, it still is.