The Diderot effect is the term for when you buy something new, but then it makes your other possessions look old and used up by comparison, so you end up replacing them, too. The Diderot effect works because we invest possessions with so much symbolic power. Often we’ll buy things we don’t really need because of the symbolism applied, a faster computer or the latest iPhone for example, when our old one is meeting our needs perfectly well.
The Diderot effect can lead us to a never ending spiral of shopping because every time we upgrade one item we’ll find that other items need to be upgraded as well. Each time we upgrade an item we’ll feel happy for a short time, until we realize we need to upgrade something else. It’s easy to see how we can get trapped in the spiral of shopping for happiness.
For more on this topic, check out Can you shop your way to happiness? by Oliver Burkeman posted at The Guardian.