Key takeaways
- Most of these tactics sell the set, not the item. They show you the new thing already surrounded by the things it will make you want.
- Each tactic works at a predictable moment, at checkout, on the product page or right after a gift, so you can decide in advance how you will answer it.
- The counter-move is nearly always the same. Separate the first purchase from the follow-ons, and make each follow-on its own decision, on its own day.
When Grant McCracken named the Diderot effect in 1988, he described a force that keeps a person’s possessions consistent with one another. For a seller, that force is a gift. The first sale is the hard one: you have to want something new. After that, the new thing does the selling, by making the old things beside it look wrong. Much of modern retail is arranged to put the next link in the chain within easy reach. Here are eight of the most common tactics, how to recognize each one, and the counter-move.
1. The complementary product
A printer needs ink, a grill needs tools, a new phone needs a case. Some pairings are real necessities. Marketing researchers have long modeled how buying one item raises the odds of buying its complement, and how a change in the price of one shifts sales of the other. The tactic lies in stretching “needs” to cover things that are merely nice beside the main item.
How to spot it. Phrases such as “pairs perfectly with,” “you’ll also need” and “essentials for your new…” on the product page.
Counter-move. Buy the main item alone and use it for a week. What you actually need will show up in that week. The rest will not.
2. “Complete the look”
The jacket is photographed on a model wearing trousers, shoes, a bag and a watch from the same store, all linked below the picture. A sofa appears in a room where every cushion and lamp has a price tag. The product is sold as a member of a set, which is exactly how McCracken said we judge our things.
How to spot it. The item never appears alone, and the styled photo comes with a shopping list.
Counter-move. Look at the item on a plain background, or imagine it with three things you already own. If it only works in the store’s set, it will pull that set into your home. A personal uniform makes this test fast for clothes.
3. The accessory at checkout
Retailers track how often a main sale comes with an add-on, and staff are often trained to ask. The moment is chosen with care: you have just committed to the big purchase, and a case or a protection plan looks small beside it.
How to spot it. The question comes after you have said yes to the main item: “Do you have a case for that?” “Would you like to protect it?”
Counter-move. Decide on accessories before you go in, and say “just the item, thanks.” Anything you skip can be bought later, usually for less, once you know you need it.
4. Bundles and starter kits
The camera with a bag, two lenses and a tripod. The espresso machine with a grinder and a milk jug. The starter kit for a new hobby. Bundling is one of the oldest pricing strategies, and a review by Stefan Stremersch and Gerard Tellis sets out the many forms it takes. For the buyer, a bundle can be a real saving. It also pre-builds a chain and prices it as one decision.
How to spot it. The headline is the discount, not the total, and the kit includes things you would have chosen differently or not at all.
Counter-move. Price only the pieces you would buy on their own anyway. If those cost less separately than the bundle, the “saving” is the price of the extras.
5. Ecosystems and lock-in
Some devices work best, or only, with other devices from the same maker: the watch that pairs fully with one brand of phone, the earbuds that switch seamlessly within one family, the smart lights that need the same hub. Economists call the cost of leaving a switching cost, and it is part of what holds customers in place. An ecosystem is a Diderot unity that the seller designed in advance.
How to spot it. Key features are described as working “with your other devices” from the same brand.
Counter-move. Price the ecosystem when you buy the first device, as a chain, and prefer products that follow open standards so the next purchase stays a free choice.
6. “Customers also bought”
The row of related products under almost every online listing is matched, item by item, to what other shoppers bought together. Banks and other sellers go further and study the order in which customers acquire related products, so they can time the next offer. The effect is to put the most likely next link one click away.
How to spot it. The recommendations change as you add items, and they always lean toward completing a set.
Counter-move. Shop from a written list and close the tab when the list is done. A recommendation is a guess about your chain, not a need.
7. The staged showroom
Furniture showrooms and model homes are dressed as complete rooms, each piece chosen to flatter the others. Researchers studying “consumption constellations” have mapped how people link whole sets of products to a role or a way of life. A staged room sells that picture. Your own room, with its old rug and its everyday clutter, will not look like it.
How to spot it. Everything in the room is for sale, and the lighting is better than yours.
Counter-move. Take a photo of your own room before you go, and hold the piece you like up against it, not against the display.
8. The free upgrade
The free upgrade to a better model, the premium trial, the gift with purchase. Diderot’s own chain began with a gift. A free upgrade is the cheapest way for a seller to put a newcomer into your set, and research by Silvia Bellezza and colleagues found that people treat what they own more carelessly when an appealing upgrade is available.
How to spot it. Something better than what you own arrives at no cost, with nothing in your home that matches it.
Counter-move. Treat a free item as the first link in a chain. Write down what it will make look wrong before you accept it, and remember that you are allowed to decline, or to leave it in its box.
The common thread
Every tactic on this list does the same thing: it presents the set, so that the follow-on purchases arrive bundled with the first decision. Juliet Schor’s advice in The Overspent American was to start by noticing the process. Our seven rules for stopping a chain turn that into habits, the 30-day rule slows the follow-ons, and the Chain Cost Calculator puts a number on the set before you buy into it. For the bigger picture, see the Diderot effect in economics.
Questions readers ask
Is using the Diderot effect in marketing dishonest?
Not in itself. Showing a sofa in a furnished room, or pointing out that a camera needs a memory card, is useful information. It becomes a problem when the presentation makes a set feel necessary, or hides its total price behind the price of the first item. Knowing the tactics lets you take the useful part and leave the rest.
Why do stores care so much about accessories?
Because an add-on is the easiest sale in the store. The customer is already at the register, has already said yes to something bigger, and judges the extra against that larger price rather than on its own. A case or a protection plan that would be a hard sell by itself rides on a decision already made.
Do recommendation rows actually change what people buy?
They are built to. The "customers who bought this also bought" row on large shopping sites matches each item to others that tend to be bought with it. That makes the most common next link in the chain the easiest thing on the page to click.
How can I shop without getting pulled into a set?
Shop from a written list, look at the product alone rather than in its styled photo, decide on accessories before you reach checkout, and give any follow-on purchase a waiting period. Our seven rules for stopping a chain go into each step.
Sources
- Culture and Consumption (Grant McCracken, Indiana University Press, 1988; this page is the 1990 paperback) Chapter 8 introduces Diderot unities, the sets of goods that feel as if they belong together, and the Diderot effect that keeps them consistent.
- The Overspent American: Upscaling, Downshifting, and the New Consumer (Juliet Schor, Basic Books, 1998), library record Schor discusses the Diderot effect as part of the upward pressure on what households feel they need, and argues that the first defense is noticing the process.
- Manchanda, Ansari and Gupta (1999), The shopping basket: A model for multicategory purchase incidence decisions, Marketing Science 18(2) How buying in one category raises the chance of buying in a complementary one, and how a price change in one shifts purchases in the other.
- Stremersch and Tellis (2002), Strategic bundling of products and prices: A new synthesis for marketing, Journal of Marketing 66(1) A review that classifies bundling strategies and sets out when each one pays for the seller.
- Linden, Smith and York (2003), Amazon.com recommendations: Item-to-item collaborative filtering, IEEE Internet Computing 7(1) The method behind rows of items that other customers bought together.
- Li, Sun and Wilcox (2005), Cross-selling sequentially ordered products: An application to consumer banking services, Journal of Marketing Research 42(2) Evidence that customers buy related products in a predictable order, which sellers use to time their next offer.
- Solomon and Buchanan (1991), A role-theoretic approach to product symbolism: Mapping a consumption constellation, Journal of Business Research 22(2) Research on the sets of products people associate with a social role, the shopper's version of a Diderot unity.
- Farrell and Klemperer (2007), Coordination and lock-in: Competition with switching costs and network effects, Handbook of Industrial Organization, volume 3 The economics of switching costs, the reason ecosystems hold on to their customers.
- Bellezza, Ackerman and Gino (2017), Be careless with that: Availability of product upgrades increases cavalier behavior toward possessions, Journal of Marketing Research 54(5) Studies showing that an appealing upgrade makes people careless with what they already own.
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