Put two identical cookies in front of someone, one from a full jar, one from a jar with almost none left, and they'll tell you the scarce one tastes better. The cookie didn't change. The supply did. That small, slightly absurd finding is a window onto a set of levers that quietly steer hiring, pricing, fundraising, and your own next decision.

The quick version

  • Scarcity and FOMO work because we read "running out" as a signal of value and we hate being the one left out, the same instinct, aimed at things or at experiences.
  • Loss aversion is the engine underneath: losing something hurts more than gaining the same thing pleases, so "you'll miss out" beats "you'll gain."
  • Nudges and defaults are the gentler end of the toolkit, change what happens when people do nothing, and you change what most people do.
  • The honest line: a fair lever steers toward a genuinely good option and leaves the exit easy. If you'd be embarrassed to explain the design out loud, it's a dark pattern.

The idea in depth: scarcity, FOMO, and the loss underneath

The cookie study is real. In 1975, Stephen Worchel, Jerry Lee and Akanbi Adewole reported in the Journal of Personality and Social Psychology ("Effects of Supply and Demand on Ratings of Object Value") that people rated cookies from a near-empty jar as more desirable than identical cookies from a full one, and rated them higher still when they had watched the jar empty. Scarcity raised perceived value; newly arrived scarcity raised it more. Robert Cialdini built the scarcity principle of his 1984 book Influence: The Psychology of Persuasion on exactly this: we treat "less available" as a proxy for "better," partly because if others are taking it, they may know something we don't.

FOMO, the fear of missing out, is scarcity pointed at experiences rather than objects, and it has real research behind it, not just marketing folklore. Andrew Przybylski and colleagues defined and measured it in "Motivational, Emotional, and Behavioral Correlates of Fear of Missing Out" (Computers in Human Behavior, 2013), describing FOMO as "a pervasive apprehension that others might be having rewarding experiences from which one is absent." Their data tied higher FOMO to people whose basic psychological needs, autonomy, competence, relatedness, were less satisfied. For a leader that's a tell: FOMO isn't only a consumer trigger, it's a symptom of how met or unmet your people feel.

So the move is: when you want action, make the cost of waiting concrete and the window real. "Two places left on the leadership cohort, and the next intake is in March" pulls harder than "places are available", because it names what's lost by not moving. The discipline is in the word real: invented scarcity ("only 3 left!" when there are hundreds) works once and corrodes trust forever. Use scarcity when it's true; never manufacture it.

flowchart TD
  A(["Loss aversion
a loss stings more
than an equal gain"]) --> B(["Scarcity
'running out' reads
as a signal of value"])
  A --> C(["FOMO
missing the experience
others are having"])
  B --> D(["The pull to act now,
before it's gone"])
  C --> D
  D --> E(["Honest use:
the scarcity is real
and the exit stays open"])
Scarcity and FOMO are loss aversion wearing two different coats, one for things, one for experiences. Leaders Loop

Loss aversion is the lever under the levers

Why does "you'll miss out" beat "you'll gain"? Because of the most load-bearing finding in the field. Daniel Kahneman and Amos Tversky's prospect-theory work ("Prospect Theory: An Analysis of Decision under Risk," Econometrica, 1979) showed that we judge outcomes as gains or losses from a reference point, and the curve is steeper on the loss side. A potential loss looms larger than an equivalent gain. Scarcity and FOMO are just loss aversion with a deadline attached: the thing you're about to lose is the cookie, the cohort place, the experience everyone else is having.

So the move is: frame the choice from the reference point your audience already holds. A team will fight to protect a budget line they would never have requested from scratch, because cutting it is framed as a loss. Use that honestly: when you want adoption of a new process, anchor on what people keep or stop losing ("this ends the Friday data-cleanup") rather than abstract upside. And turn the lens inward, the same pull makes you defend a failing project past the point of sense. Naming "I'm protecting against a loss here" is half the cure.

The idea in depth: nudges and defaults, the no-coercion end

Scarcity and FOMO are sharp instruments. The gentler, and often more powerful, lever is the default: whatever happens when a person does nothing. Richard Thaler and Cass Sunstein named the discipline in Nudge (2008; revised as The Final Edition, 2021), with one uncomfortable premise, there is no neutral choice. Someone always decides what the form pre-fills, which option sits first, what continues automatically. That someone is shaping behaviour whether they intend to or not.

A nudge steers without shoving. The test of a fair one: the option you favour is genuinely good for the person, and the exit is two clicks away.

The cleanest evidence is almost unfair in its starkness. In "Do Defaults Save Lives?" (Science, 2003), Eric Johnson and Daniel Goldstein compared organ-donation rates across European countries. Nations where you're a donor unless you opt out had effective consent rates near 90%; comparable countries where you must opt in sat closer to 15%, same broadly similar populations, wildly different outcomes, driven almost entirely by which box was pre-ticked. People didn't choose the default because they'd weighed it. They chose it because choosing is effort, and the default is the path of no decision.

So the move is: audit your defaults, because they are quietly doing your real policy. The meeting that recurs unless someone cancels it, the report nobody remembers to stop, the renewal that auto-continues, the "reply-all" that's pre-selected, each is a default carrying a behaviour. If you want something to happen, make it the do-nothing path. If you want something to stop, the change that pays off most is usually removing it from the default, not adding a rule on top.

flowchart LR
  A(["You want a
behaviour to happen"]) --> B(["What happens if
the person does nothing?"])
  B --> C(["That do-nothing path
is your real policy"])
  C --> D(["Make the good option
the default, opt-out,
pre-selected, automatic"])
  D --> E(["Leave the other
options easy to reach"])
The default is a decision you're already making for people. Make it deliberately, and keep the door open. Leaders Loop

The honest limitation: the effects are real, but softer than the hype

Behavioural levers sell a tempting promise, small tweak, big result, and the literature has been caught overselling it. In "No evidence for nudging after adjusting for publication bias" (PNAS, 2022), Maier and colleagues re-analysed a large nudge meta-analysis and argued that once you correct for studies with null results never getting published, the average nudge effect shrinks dramatically, by their estimate, close to nothing. The original authors pushed back, and the truth is contested rather than settled: some nudges (defaults especially) hold up well; many published effects are inflated. So the honest stance is to treat these levers as a checklist of things worth trying and measuring, not as dials with guaranteed settings. Run the cheap test in your own context before betting the quarter on the size of an effect. That scepticism is itself the behavioural mindset, turned on its own claims.

A worked example

You run an internal leadership programme and want more managers to actually finish it. Sign-ups are fine; completion is poor. The reflex is to email harder. (All figures here are illustrative.)

Instead, pull the levers honestly. Default: stop asking people to opt in to each module. Enrol every new manager into the full cohort by default, with an easy "not this round" link, the Johnson–Goldstein lesson applied to learning. Loss-aversion frame: instead of "complete the course to earn a certificate" (a gain), show progress as something at risk, "you've completed 4 of 6 modules; your place pauses if the last two lapse", so finishing protects what's already been built. Real scarcity / FOMO: run it as small, dated cohorts ("June intake, 10 seats, peer group fixed") rather than an always-open library, so there's a genuine room to be part of rather than an endless to-do.

Suppose completion moves from 35% to 58% (illustrative). You didn't add budget or pressure, you changed the default, the frame, and the structure. And you could explain every choice to the managers without flinching: the cohort is real, the deadline is real, the exit is one click. That's the whole ethics of this toolkit. A nudge you can describe out loud to the person you're nudging is fair; one that only works because they don't notice it is a dark pattern, worth avoiding even when it converts.

Frequently asked questions

Isn't this just manipulation dressed up?

It can be, that's the dark-pattern version, where the scarcity is fake, the "default" serves you at the person's expense, or the loss is invented. The honest version passes a plain test: the option you're steering toward is genuinely good for them, and you'd be comfortable explaining the design out loud. Thaler and Sunstein call this "libertarian paternalism", steer, but always leave the exit easy and cheap.

Does FOMO actually work on serious, experienced people?

The pull of scarcity and missing out shows up well beyond impulse shoppers, in executives weighing deals and in professionals who pride themselves on being rational. Przybylski's research frames FOMO as tied to unmet psychological needs, which is exactly why it doesn't switch off with seniority. The defence isn't being too smart to feel it; it's building checks, naming the deadline, asking "would I want this if it weren't scarce?"

What's the difference between a nudge and a rule?

A nudge changes the default but leaves every option open and cheap to reach; a rule removes options or adds real cost. Auto-enrolling staff in a development cohort they can leave in two clicks is a nudge. Mandating attendance is a rule. Reach for the nudge first, it's cheaper, less resented, and respects that people sometimes have good reasons to opt out.

If the research is contested, why use any of it?

Trust the direction, verify the size. That losses, scarcity, FOMO and defaults influence behaviour has held up across decades; how big the effect is in your setting is exactly what the publication-bias debate says varies. So treat any published effect size as a hypothesis and run a small test before scaling. Defaults are the safest bet of the set; sharp scarcity tactics, the least reliable.

What should I change first?

Your defaults. Most leaders pour energy into persuasion and incentives and never look at what happens when people do nothing, which is what people do most of the time. Find the choices in your organisation that run on inertia and ask whether the do-nothing path leads somewhere good. Fixing that is usually cheaper, and more durable, than any campaign.

Related in the Toolkit

Where to go next