The IKEA effect is a term derived from the name of the IKEA furniture company that largely deals in furniture which is meant to be assembled by the purchaser in order to reduce cost.
According to research conducted by Michael I. Norton, Daniel Mochon, and Dan Ariely, the IKEA effect occurs when a person puts a disproportionate value on something they created. In relation to this, it refers to a greater sense of pride that a person may take in an event, decision, or achievement that they actually took part in creating.
There is believed to be a relation with justification of effort which has shown that the more effort someone puts into creation or an action the more it will be valued by that person. Marketers noted in the 1950s instant cake mixes were not selling well as homemakers felt they weren't invested in the process and didn't value the result as they didn't really contribute to it. By simply adding a step that required an egg to be cracked made the bakers feel more involved and therefore they valued the results more -- increasing instant cake mix sales.