What is the Diderot effect?

Imagine you buy a new shirt. You did not intend to buy a new jacket. You were perfectly happy with it until you wore it with the new shirt, However, you imagine that the new shirt makes the old jacket look worn. You weaken and buy a new jacket. You may then feel the need to buy new trousers. And perhaps new shoes. Before you realise it, you have a whole new wardrobe.

New clothes, new you. And maybe an empty bank account.

The Diderot Effect is often cited among reasons as to why people overspend, and it’s not hard to see why: a single item can trigger a string of purchases that could make the ‘new you’ someone who has to take up a few night time Deliveroo shifts in addition to their regular job.

The term Diderot Effect was coined by Grant McCracken in 1988 and explained that people’s purchases don’t depend solely on an item’s functionality or practicality.

The traditional belief that people made purely rational decisions would assume they would only replace or upgrade something once it no longer worked.

However, McCracken said that purchases are tied more closely to a person’s identity than to pure practicality.

This is an idea that companies have been playing with for a long time in an attempt to convince people to buy not just one product, but a whole series of them.

A great example is also mentioned in this video on the Diderot Effect by the BBC: IKEA. Anyone who has been to an IKEA is familiar with their display rooms.

These fully fitted and designed rooms are there to give you a sense of the type of person who would live there. And if you think that person is you, then buying that new sofa may also mean buying the TV furniture and the coffee table, to match, and so on.

The Diderot Effect tells us two things about ourselves:

1. We buy goods that complement each other and build towards a unified image we have of our own identity.
2. If we obtain an item that doesn’t fit that identity, we’ll be tempted to either disregard it or we’ll make it the centrepiece of our new identity (the ‘new you’).

This means we care about buying things, which in our opinion work together, and that we believe fit with who we are.

Denis Diderot, the eponymous 18th century French philosopher, ran into that very issue when he was gifted a fancy new bathrobe.

All of his other possessions simply didn’t live up to the pristine nature of the new robe and so he ended up replacing his shabby possessions to suit his new bathrobe.

In regular day-to-day life, the Diderot effect could mean that, just like Monsieur Denis Diderot, you’ll buy whatever you feel matches that classy new bathrobe.

For most, this may not pose a serious problem. Sure, they’ll feel a dent in their wallet that month, but they’ll recover.

But in the extreme, some may use up any savings they have and even fall into debt to satisfy their need for ‘the new’. Here are two pitfalls to look out for:

1. Simply seeing what is on offer is enough to trigger the Diderot Effect – window-shopping is not always as innocent as it seems. You don’t need to buy something new to feel the urge for a change, just seeing the options of the different ‘new yous’ available can do it.
2. Beware the snowball effect – what may start with new clothes can rapidly spiral to changing the wardrobe which doesn’t now seem right for the new clothes, and then the bedroom furniture that doesn’t fit with the new wardrobe, and so on. Your key defence against these traps is awareness. If you are aware that your purchases are being driven by the Diderot effect, you might be able to stop unnecessarily over-consuming.

Always beware, you’re no longer being sold only a single product, but an entirely new lifestyle – a new you.