In the mid 1900s, sales of cake mixes were lagging. The boxed mixes had recently been introduced, but the product simply wasn't taking off.
One day, someone at General Mills had the insight to take the dried eggs out of the mix.
As the story goes, sales immediately started to increase. All of a sudden, people felt ownership over the final product, and adding their own eggs assuaged people of their guilt over not making their family a "real" cake.
The problem with the story is that it's mostly not true.
For starters, cake mixes simply taste better when the eggs are added fresh. Plus, an overall decline in formal exposure to cooking, coupled with a shift in home economics courses to using prepackaged mixes, solidified their popularity.
But the story has staying power, because it speaks to some underlying truths about craft and care.
The Ikea effect is the cognitive bias associated with placing a higher value on something you've crafted yourself, rather than purchased fully formed. The effect is named, of course, after the sense of satisfaction you get from assembling your own flat-pack furniture from Ikea.
When we're involved in the creation of something — even if our involvement is simply adding water and an egg, then baking it — we tend to like the final product more.
There's also something intangible at play in the cake mix story. All else being equal, we enjoy a cake made from scratch more than one from a box, because we know how much more work went into the former.
A cake made from scratch by someone who cares about you is more than just sugar, butter, and flour.
It's also got another ingredient that you'll never find listed on a box.