The Free Thing Is the Door

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On the forest floor in Borneo there’s a plant that solves a problem most plants never face. The soil where it grows is poor, stripped of nitrogen, and a root system alone won’t feed it. So it does something ambitious. It grows a jug.

The jug hangs from the end of a leaf, about the size of a coffee mug, with a broad curved rim running around the opening. Along the inside edge of that rim sit nectar glands, and they produce sugar. Real sugar, not a chemical imitation or a lure with nothing behind it. For an ant working a foraging route through the leaf litter, it’s an excellent find.

So the ant climbs the jug, walks the rim, drinks, and goes home. Nothing bad happens. It does the same thing the next day, and the day after that. Eventually it does what ants do when they find a reliable food source. It lays down a trail and brings the colony.

Here’s the part the ant has no way of knowing. The rim is made of a surface that behaves completely differently depending on whether it’s wet. Dry, it’s perfectly grippable, and an ant can stroll across it all afternoon. Wet, from rain or overnight condensation or from the nectar itself pulling moisture out of the humid air, it becomes one of the most slippery surfaces in the natural world. Insects don’t so much fall in as aquaplane in.

Researchers at Cambridge measured this in the field on Nepenthes rafflesiana and found capture rates swinging from zero to above eighty per cent depending on nothing but the wetness of that rim. And when they later experimented with keeping the rim permanently wet, the plant caught fewer ants, not more. A trap that’s always on gets avoided. A trap that’s off most of the time gets a scout, then a trail, then the whole column at once.

The nectar was never the trick. The nectar was completely genuine, and its genuineness was the entire mechanism. Pull the nectar glands out and the plant catches less. The free thing was real, it was reliable, and that’s precisely why it worked.

The line that isn’t a price

Somewhere between one cent and nothing, your brain stops doing arithmetic.

This isn’t a figure of speech. In 2007, Kristina Shampanier, Nina Mazar and Dan Ariely ran an experiment that’s since become one of the most cited papers in marketing. They offered people a choice between a Hershey’s Kiss and a Lindt truffle, a cheap chocolate and a good one. When the Kiss cost one cent and the truffle fifteen, most people chose the truffle. Then the researchers dropped both prices by exactly one cent. The Kiss became free, the truffle fourteen cents. The gap between them hadn’t moved at all.

Preferences flipped. People abandoned the truffle and grabbed the free Kiss in droves. Standard economics has no room for this, because the relative deal was identical in both conditions. What changed was that one option had crossed a border. The researchers concluded that people don’t treat zero as the bottom of a price scale. They treat it as a different kind of thing altogether.

I want to give that idea a name, because it does more damage than almost any other feature of financial psychology, and it does the damage invisibly. Call it the Zero Line. On one side of it, your brain runs a comparison: what do I get, what does it cost, is the trade worth making. On the other side, the comparison doesn’t run at all. There’s no cost term to put in the equation, so the equation doesn’t get set up. What you’re left with is pure appetite.

Why nothing switches something off

Two things happen at once when a price hits zero, and they compound.

The first is that the pain of paying disappears. Handing over money activates the same neural machinery associated with processing losses, which is why spending feels like something rather than registering as a neutral swap. Zero removes the sting entirely, so appeal is all that’s left in the room.

The second is subtler. Evaluation is effortful, and your brain allocates that effort roughly in proportion to what’s at stake. A price is a signal that something’s at stake. Remove it and you’ve removed the cue that told your mind to bother thinking, so the offer sails through the checkpoint because nothing flagged it for inspection.

Which means the danger of free was never that free things are bad. Most of them aren’t. The danger is that free arrives with your judgement switched off, and whatever comes attached to it arrives the same way.

The candy that taught us manners

Now for the finding that makes this genuinely strange.

Ariely and his colleagues also ran a study in which students were offered candy from a large box, either free or for the nominal price of a cent. As you’d expect, far more students took candy when it was free. The surprising part was how much each person took. When the candy was free, the great majority took exactly one. When it cost a single cent, the students who bought it often took several.

Free makes more of us want in. But it can also make each of us take less.

A price puts you in a market: you’ve paid, the transaction is settled, and maximising what you receive feels like your right. Remove the price and social norms enter the exchange. Taking too much no longer looks like getting a bargain. It makes you the person who took too much. Ariely describes these as market norms and social norms, and the switch between them can be abrupt.

This helps explain part of the architecture of the free sample. The taste may genuinely sell the product, but the gift changes the interaction too. A commercial exchange acquires a social layer. A stranger has just given you something, and you’re now standing there holding a toothpick and feeling faintly obliged.

The candy study was about restraint, but another social norm can now enter too: reciprocity. That’s one reason a free financial seminar may come with dinner. It may also be part of what makes free consultations, portfolio reviews and retirement planning sessions commercially useful. The meal may be hospitality, but it’s also a lever. You might not experience it as a debt, but you’re now slightly more inclined to return the favour.

What the free thing opens onto

In September 2004, Oprah Winfrey told a studio audience of 276 people that every one of them was getting a car. The footage is still circulating twenty two years later, and for good reason. It’s genuinely joyful television.

The cars were real. Brand new Pontiac G6 sedans, donated by Pontiac out of its advertising budget, worth around twenty eight thousand dollars each. What the audience didn’t yet know was that the tax office treats a car you’ve won as ordinary income. Winners were left with bills of roughly six to seven thousand dollars. Some took out loans to keep their free car. Others traded down to something cheaper, or let the car go.

Nobody deceived anybody. The car was free, exactly as advertised, but there was a hidden catch. That’s often true of a free offer. Free shipping over eighty dollars, so you add a fourth item to a cart that held three. Free delivery on the app, funded by menu prices set higher than the ones in the restaurant. A free trial that ends by charging you, on a date you agreed to and won’t recall. Free banking, free super comparison tools, free credit score checks that exist to sell you products. Someone paid for all of it, and it wasn’t the company.

The most useful question to carry into any free offer isn’t whether it’s a scam. Usually it isn’t. The question is what the free thing is a door to, and where the door leads.

The most expensive free thing in modern finance

In late 2019, the major American brokerages dropped trading commissions to zero within weeks of each other. Australian platforms followed with their own versions, from zero brokerage on selected trades to app based investing with no upfront fee.

The thing is, zero commission trading did genuinely reduce what retail investors pay to trade. The full picture is that the brokers made money elsewhere, largely through selling order flow to market makers, and there was real concern that worse execution prices would eat the savings. But when researchers actually measured total retail transaction costs before and after the change, costs fell. The free lunch was, in narrow dollar terms, mostly real.

The bill arrived somewhere else entirely. What a commission does, apart from cost you money, is make you stop and think. Twenty dollars a trade is a small tax on impulsiveness, and small taxes on impulsiveness are worth a great deal more than they cost. Take it to zero and you’ve made it weightless. No friction.

We have a fairly clear idea of what happens next. Barber and Odean’s landmark study of 66,465 households at a discount broker found that the most active traders earned 11.4 per cent a year while the market returned 17.9 per cent. Six and a half percentage points, annually, for the crime of doing more. Later work by Barber, Huang, Odean and Schwarz found that users of zero commission app platforms engaged in noticeably more attention driven trading, piling into whatever was loud that week.

So the commission you saved was maybe ten dollars. The behaviour the missing commission encouraged can cost multiples of that every year, compounding, for as long as you keep it up. Free removed the friction, and the friction was doing something valuable that nobody had thought to put a price on.

When free goes the other way

There’s a twist here that saves this from being a simple warning, and it’s one of my favourite findings in the whole area.

Zero pricing can backfire. Xiaomeng Fan, Fengyan Cindy Cai and Galen Bodenhausen ran five studies showing that when an offer carries what they call high incidental costs, meaning it’ll take real time or effort or involve some risk, a free version attracts less demand than a cheaply priced one. The trigger for the research was the observation that older residents in some Chinese cities were declining free flu vaccinations and paying for them instead.

Their explanation is that zero fires two processes simultaneously. It generates a warm rush of appeal AND it generates suspicion, a nagging question about what’s wrong with this. When the other costs are trivial, appeal wins easily. When they’re substantial, suspicion takes over and free starts reading as worthless.

Which tells you something quite specific about your own mind. Your scepticism about free isn’t absent, it’s just badly calibrated. It fires hardest when the stakes are visible and effortful, and it goes to sleep exactly when a free thing is easy to accept, which is when free does most of its work on you.

Five questions to ask at the rim

Run the one dollar test. Before accepting anything free, ask whether you’d take it at a dollar. Not fifty dollars, a dollar. If a dollar makes you hesitate, the thing was never worth having and free was doing all the persuading. This single question restores the evaluation that zero switched off, and it takes about two seconds.

Ask what it’s a door to. Free things are rarely the transaction. They’re the entry point to one. Look past the offer to the structure behind it: what happens on day thirty one, what the renewal price is, what you’ve had to hand over, who gets paid when you walk through. If you can’t work out where the money comes from, you haven’t found the answer yet.

Price the currencies that aren’t money. Zero refers only to dollars. It says nothing about your time, your attention, your data, your cupboard space or the mental load of one more account to manage. A free thing that costs you two hours isn’t free, it’s an hourly rate you agreed to without negotiating.

Put back the friction that free removed. Where zero has stripped out a pause, install one deliberately. A written rule that you don’t trade for forty eight hours after deciding to. A note of the renewal date in your own calendar rather than theirs. Deleting the app that makes buying take four seconds. You’re rebuilding a checkpoint that used to exist for a reason.

Accept the sample, decline the obligation. Take the free coffee, eat the free seminar dinner, use the free consultation. Then say a cheerful thank you and leave without deciding anything. The reciprocity you feel is real, well documented and entirely engineered.

A fair word before anyone feels lectured

None of this is an argument that free is a trick and you should be suspicious of generosity. Free is awesome. It’s how enormous numbers of people access things that genuinely improve their lives: libraries, public health services, no fee transaction accounts, community programmes, open source software, the free tier of things that would otherwise be out of reach. Free can absolutely be the difference between having something and not.

The distinction worth considering is between free as access and free as an acquisition channel. One is designed to get something to you. The other is designed to get you somewhere. They can look identical from the outside, and telling them apart takes about ten seconds of asking who’s paying for this and what they want in return.

Back to the rim

Think about that ant one more time, because it wasn’t foolish. It found a reliable source of good food, it took the food, and nothing bad happened. It did that many times. Every piece of evidence it gathered said the rim was safe, and every piece of evidence was accurate. The disaster was caused by a habit, built on a hundred honest transactions, occurring when the conditions had changed.

Free works the same way on us. Not by deceiving anybody, mostly, but by getting us to walk a particular rim often enough that we stop looking down. The free trial you cancelled in time, the sample you took and didn’t buy, the trade that cost nothing and worked out fine. All real, all harmless, and every one of them teaching you that this is a surface you don’t need to check.

The next time something arrives with a zero on it, don’t ask whether it’s too good to be true. That question flatters your scepticism and rarely catches anything. Ask the far duller question instead: what am I standing on, and what changes when it rains.

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