How Inflation Eats Savings: The Error Behind the Erosion

Researchers replicated a landmark study on how people handle inflation, then added an extension to test something obvious: does knowing the inflation rate protect you from misjudging it?

The answer was no. They found no support for the notion that knowing about or correctly estimating the inflation rate affected money illusion.

Which means the standard advice on this topic — understand inflation, be aware of it, factor it in — was tested and didn’t work.

The Short Answer

Inflation erodes savings by reducing what each unit of currency buys, so cash held at a return below the inflation rate loses real value even while the balance grows. But the larger cost is perceptual: people systematically evaluate money in nominal terms, which causes them to accept real losses that look like nominal gains — and knowing the inflation rate doesn’t correct it.

The Bias Isn’t Ignorance

Money illusion is the tendency to think in terms of nominal rather than real monetary values. The original 1997 paper by Shafir, Diamond and Tversky proposed something more precise than “people don’t understand inflation,” and the precision matters.

Their argument: people think about transactions in both nominal and real terms simultaneously. The illusion arises from the interaction between those two representations — and the nominal one wins, because the nominal representation of money is more salient and simpler than the real one.

So the real-terms calculation is present. It’s just louder in the other channel. You aren’t missing the information — you’re being outvoted by the version of the number that’s easier to hold in your head.

That explains why the education fix fails. You can add more information to a system whose problem isn’t a shortage of information, and nothing happens.

The Three Errors That Actually Cost You

The erosion of purchasing power is the part everyone knows about. These are the decisions the illusion causes, and they do more damage:

Accepting a real pay cut as a raise. The research names this directly — the oversized appreciation of a nominal wage raise that is actually a real wage cut in times of high inflation. A 4% increase when prices rose 6% is a 2% pay cut that arrives feeling like good news. You’ll thank someone for it.

The inverse is Keynes’s sticky wages, which Brookings summarises well: if prices fall and nominal wages fall equally, workers are no worse off than before, but they still resist the cut because a loss in dollar terms is hard to bear. Same real position, opposite emotional reaction, purely from which number is displayed.

Refusing to sell at a nominal loss that’s a real gain. The reluctance to sell a house or an asset because the headline number is below what you paid — even when, adjusted for inflation, you’re ahead. The nominal figure anchors the decision and the real one gets ignored.

Treating cash as risk-free. This is the most expensive one for most people. Cash carries no nominal risk and substantial real risk, and because the nominal number never falls, the loss is completely invisible. Your balance goes up every month while what it buys goes down. There is no statement, no alert, no moment where anything looks wrong.

That invisibility is why this compounds so effectively against people who are otherwise careful with money.

Why “Just Be Aware of Inflation” Is Bad Advice

The replication finding deserves more weight than it gets. Awareness was tested as a moderator and didn’t moderate.

And this is a well-replicated effect, not a fragile lab curiosity — the original work has been reproduced with 604 participants online and separately in a Brazilian sample of 372 participants, with results closely mirroring the original findings. Different countries, different inflation experiences, same pattern.

My position: stop trying to be more aware of inflation and change what unit you make decisions in. Awareness is a mental correction applied after the fact, competing against a representation that is structurally more salient. It loses. What works is not having to make the correction at all.

What Actually Helps

Convert before you evaluate, not after. Any figure that spans more than a year gets adjusted before you form an opinion about it. Not “that’s a 4% raise, and inflation is 6%, so…” — that’s the awareness approach and it arrives too late. The number you look at should already be the real one.

Treat cash as a position with a cost, not as neutral. Cash isn’t the absence of a decision; it’s a decision with an ongoing charge attached. This doesn’t mean holding none — a liquid buffer earns its cost by preventing forced selling and new debt. It means holding it deliberately, sized to a purpose, rather than by default.

Negotiate against the real number. Going into a salary or rate conversation with the inflation figure already applied changes what you’re asking for. Most people anchor on last year’s nominal figure and negotiate upward from it, which builds the illusion into the starting position.

Watch for the raise that isn’t. If your income rises and your position doesn’t improve, one of two things is happening: inflation absorbed it, or your spending did. The second is the income-doubled-savings-flat pattern. They feel identical and require opposite fixes, so it’s worth knowing which one you’re dealing with.

Denominate long-term goals in things, not currency. A target expressed as a fixed sum quietly shrinks every year. A target expressed as what it needs to cover doesn’t. This is one of the few places where a small change in how you write down a goal materially changes the outcome.

Where This Interacts With Everything Else

Money illusion doesn’t operate alone, and its combinations are worse than the parts.

Paired with the systematic underestimation of compound growth, it produces a double error on any long-horizon plan: you undercount the growth and overcount what the resulting sum will buy. Both errors point the same direction, toward complacency.

Paired with present bias, it makes deferring action feel cheaper than it is, since the future cost is expressed in nominal terms that look manageable.

And it distorts the return-chasing decision in both directions. Someone who over-corrects for inflation takes more risk than their situation warrants, which runs into the sequence problems covered in consistent compounding returns. Someone who under-corrects holds cash indefinitely. Both are responses to the same misperception.

The Honest Limits

Two things worth stating rather than glossing over.

First, published inflation figures are averages across a basket that may not resemble your spending. Your personal inflation rate depends on your housing situation, whether you have children, how much you drive, and where you live. The headline number is a starting point, not a personal measurement — and for some households it substantially understates what they experience.

Second, and more importantly: nothing above tells you what to hold instead of cash. That’s a genuinely different question involving risk tolerance, time horizon, and jurisdiction, and the honest answer is that the correct response to “cash loses real value” is not automatically “so buy assets.” Over-correcting into volatile positions you’ll exit at the wrong moment can cost more than the erosion you were avoiding — which is why the sequencing questions come before the allocation ones.

What this article can say confidently is narrower and still useful: the perception error is real, well-replicated, and not fixed by knowing the inflation rate. Changing the unit you think in is the intervention with actual evidence behind it.

Questions Worth Asking

If knowing the inflation rate doesn’t help, what does?

Changing the unit you evaluate in rather than applying a mental correction afterwards. Adjust any figure spanning more than a year before you form an opinion about it, so the number you’re reacting to is already the real one. The correction fails because it competes against a representation that’s structurally more prominent; pre-conversion avoids the competition entirely.

Is holding cash always a mistake during inflation?

No. Cash held for a defined purpose — a buffer that prevents forced selling or new borrowing — earns its cost. The mistake is holding it by default, without a purpose or a size, while believing it carries no risk. Deliberate cash and residual cash are different positions.

How do I know whether my raise was real or nominal?

Compare the percentage increase against inflation over the same period, before you decide how you feel about it. If the increase is smaller, your real income fell. Doing this comparison before rather than after the emotional response is the entire trick.

Does money illusion affect people in high-inflation countries less?

Replication in a country with substantial inflation experience produced results closely mirroring the original findings, which suggests exposure alone doesn’t neutralise it. That’s consistent with the wider finding that knowing the rate doesn’t help.

Should I use the official inflation figure or estimate my own?

The official figure is a reasonable default, but it’s a basket average that may not match your spending pattern. If your costs are concentrated in categories rising faster than the headline rate, the published number understates what you’re actually experiencing.