Knowledge Paper 003 · Behavioural Science

What is Costly Signalling?

Why the most believable messages are often the ones that are hardest to fake.

The short answer

Costly Signalling is an idea from evolutionary biology and psychology that explains why signals are only truly believable when they are difficult, expensive or risky to fake.

In marketing, it helps explain why people often trust what brands do more than what they say.

Anyone can claim to be the best.

Far fewer can afford to behave as though they are.

Why actions speak louder than words.

Imagine two whisky brands.

The first tells you:

“We are committed to quality.”

The second quietly matures its whisky for eighteen years before selling a bottle.

Which signal feels more believable?

The second.

Not because the words are better.

Because eighteen years is expensive.

Warehousing costs money.

Capital is tied up.

Mistakes become costly.

It is difficult for a poor-quality producer to imitate.

That is a costly signal.

Nature discovered this long before marketing.

The concept comes from evolutionary biology.

Why does a peacock grow an enormous tail that makes escaping predators more difficult?

Because only a healthy male can afford to carry such a burden.

The very cost of the signal makes it believable.

The same principle appears throughout nature.

• Large antlers.
• Birdsong.
• Elaborate nests.
• Courtship displays.

They all communicate underlying quality precisely because they are expensive to produce.

Cheap signals are easily copied.

Costly signals are harder to fake.

Humans never stopped using them.

Although our lives have changed dramatically, our psychology has not.

We still judge credibility by looking for costly signals.

Think about everyday life.

• Someone who volunteers years of their time.
• A company offering a lifetime guarantee.
• A university investing in research.
• A chef writing a cookbook.
• An airline training its own pilots.

These things communicate commitment.

Not because someone says they care.

Because they have invested something valuable.

Marketing is full of cheap signals.

“We are innovative.”

“We put customers first.”

“We are passionate.”

Anyone can write those words.

They cost almost nothing.

Consumers know this instinctively.

Which is why they often ignore them.

The more a claim resembles something every competitor could say tomorrow, the less persuasive it becomes.

The strongest brands send expensive signals.

Consider the whisky industry.

• A distillery that leaves spirit maturing for decades.
• A visitor centre built to world-class standards.
• Investment in sustainable production.
• Beautifully crafted packaging.
• Long-term sponsorship of cultural events.
• Exceptional customer service.

These all require real commitment.

They are difficult to fake consistently.

That makes them believable.

Cost creates credibility.

This is the central idea.

The signal does not work despite its cost.

It works because of its cost.

If it were cheap, everyone would do it.

Imagine a luxury whisky claiming it uses rare casks.

Now imagine discovering every competitor uses exactly the same casks.

The signal immediately loses value.

Its scarcity disappears.

Costly Signalling is not just about money.

Cost can take many forms.

• Time.
• Effort.
• Risk.
• Sacrifice.
• Commitment.

A founder personally answering customer complaints.

A distillery refusing to release immature whisky despite commercial pressure.

Publishing transparent sustainability data.

Offering an unusually generous guarantee.

These all involve meaningful cost.

That is why people notice them.

Why this matters for marketing.

Many organisations spend huge sums trying to appear trustworthy.

Often they would be better investing in behaviours that genuinely deserve trust.

Trust is rarely built by communication alone.

Communication amplifies behaviour.

It does not replace it.

Common mistakes

Confusing expensive with effective

Not every expensive activity is a costly signal.

Lavish offices or extravagant advertising may impress some audiences but mean little to others.

The cost has to communicate something relevant.

Assuming customers believe claims

Consumers have heard every superlative imaginable.

“Premium.”

“Trusted.”

“World-class.”

Without supporting behaviour, they are just words.

Copying competitors

A signal only works while it remains relatively difficult to imitate.

Once every brand behaves identically, its signalling value declines.

How to create Costly Signals.

Ask yourself:

The answer may not be another campaign.

It might be:

• a remarkable guarantee
• radical transparency
• extraordinary customer service
• investing in craftsmanship
• refusing short-term compromises
• publishing evidence
• standing behind your product for years

The best marketing often begins outside the marketing department.

Key Takeaways

• Costly Signalling comes from evolutionary biology.
• Signals become believable when they are difficult or expensive to fake.
• Consumers trust behaviour more than slogans.
• The strongest brands invest in actions that communicate commitment.
• Marketing is most powerful when it amplifies genuine evidence rather than compensating for its absence.

Frequently Asked Questions

Is Costly Signalling only relevant to luxury brands?

No.

Any organisation can create credible signals through commitment, transparency, guarantees, expertise or long-term investment.

Is expensive advertising a Costly Signal?

Sometimes.

Only if the audience interprets the investment as evidence of underlying quality or confidence.

Advertising alone is not automatically a credible signal.

Can small businesses use Costly Signalling?

Absolutely.

Exceptional service, founder accessibility, generous guarantees, specialist expertise and transparent communication can all function as powerful costly signals.

How does Costly Signalling relate to branding?

Distinctive Brand Assets make a brand easy to recognise.

Costly Signals make it easier to trust.

The strongest brands build both.

Further Reading

• Amotz Zahavi — The Handicap Principle
• Geoffrey Miller — Spent
• Geoffrey Miller — The Mating Mind
• Rory Sutherland — Alchemy
• Robert Trivers — research into reciprocal altruism

Related Knowledge

• What are Distinctive Brand Assets?

About The SignalWorks

At The SignalWorks, we believe the strongest marketing does not begin with communication.

It begins with behaviour.

Because the most persuasive message is not the one you write.

It is the one your actions have already written for you.