Ad Text and The Principles of Persuasion

A look at the six principles of persuasion from Robert Cialdini's Influence... through the lens of a PPC marketer…

Success in ad text lies in testing different messages to see what works. 

We could go pretty deep down the rabbit hole of theory about what kind of text should work and why… but all too often, theory and expectations get completely crushed by what happens in our campaigns in practice… and it’s what happens in practice that matters.

But… theory is still valuable. Effective testing should be intentional and specific… based on a hypothesis. We’ll form better hypotheses if we have a good idea of what works to persuade people, and why.

With this in mind, I recently read Robert Cialdini’s highly-rated book:Influence, all about techniques of persuasion and what causes people to comply with the wishes of others. 

And as I read it, I kept seeing how these ideas play into PPC ad text and LP content… 

So let’s take a look at the six principles of persuasion that Cialdini entertainingly explains in his book, as seen through the lens of a PPC marketer…

These are the six principles:

1 Reciprocity

2 Commitment & Consistency

3 Social Proof

4 Liking

5 Authority

6 Scarcity


 1) Reciprocity

The drive to return a favour. 

Simply, We’re much more likely to do something for someone who has done something for us.

When you give something, it creates a feeling of indebtedness that is hard to shake – even if the recipient didn’t ask for the favour.  

There’s a neat at experiment described in the book to illustrate this…

An actor gives a bottle of coke to the subject as an apparent favour, and then later asks the subject if they would like to buy some raffle tickets from them. 

Those who were given the coke bought twice as many tickets as those who weren’t (at much greater value than a bottle of coke…).

What does it mean for us marketers?

Freebies and Give-aways

If we can present a freebie to the user upfront, or frame what we’re offering as some kind of free gift, it will tap into that ‘indebtedness’ response, increasing the chances of a favourable response to any request we might make later.

Free samples also count as gifts for these purposes… (just consider the slight discomfort you feel when you take a free sample at a supermarket and then walk away.)


 2) Commitment & Consistency

People will go to great lengths – both consciously and unconsciously – to act in a way that is consistent with decisions they have already made.

Once you take a step in one direction, there’s strong drive keep going down that same path… (and of course if you can get someone to feel a strong drive in the direction that leads to a sale or conversion… happy days).

This principle is at work when we are led along a path of agreeing to being a certain type of person, in a certain type of situation, followed by the punchline: “Then you need [insert product or service]“. It’s a classic approach in ads, and you’ll see a version of it in many long-form sales pages.  

A related idea is the power of ‘commitment’… once you have explicitly agreed to something – even a trivial, obvious idea (e.g “I like to live in a clean neighbourhood”), you become much more likely to comply with some related request… (e.g. “would you come litter-picking tomorrow?”)

So for us marketers – this comes into play when we invite a small, trivial action (e.g with a ‘tripwire offer’) – then increasing likelihood of larger action (or purchase). It’s known as the Foot in the Door technique.


 3) Social Proof

This is an idea well known to marketers…. The tendency to see an action as appropriate when others are taking it.

As Caildini points out in the book, canned laughter is a prime example of this. It’s annoying as hell… but it’s there to provide social proof of how funny a show is, and it doesn’t even have to fool you consciously to work its magic.

For us marketers, star ratings, testimonials, awards, recommendations, ‘likes’, member or user numbers all draw on this psychological shortcut, and you’ll see these all over both ad text and landing pages.

Social proof is also shown to be much more effective when those seen taking an action – or responding to it in a certain way –  appear to be similar to ones self. 

This was illustrated by a devilishly clever study (you can read about here examining under what conditions people would/wouldn’t return a wallet found in the street.

 4) Liking

And that ties in with the fourth principle: Liking. We are more likely to do something for – or buy something from – someone we like than someone we don’t. No surprise there.

One place we see this is where the seller associates a purchase with taking an action for a friend. 

An example of this in book is the Tupperware Party (I haven’t been to many myself… but apparently the hostess of a Tupperware Party receives a cut of all sales that the rep makes to the partygoers, who are then – in a sense – making the purchase for a friend. Sales benefit accordingly. 

Among the many attributes and techniques that can influence likability, these two may be particularly useful:

1 Compliments. We are absolute suckers for praise – even when it’s quite plainly artificial. We seem to have an almost irresistible, automatically positive reaction to compliments. 


 2 Familiarity also improves ‘liking’. the more you’ve seen a face – even if you don’t remember having seen it – the more (in general) you like it. 

Practical applications in ad text:

Celebrity endorsements? – If you have them, mention them to draw on their likability by association.

Look for ways to compliment the user (you might have seen text like – “if you’re here, you’ve already shown you’re smarter or more motivated than 70% of people in your industry” etc…

As for familiarity, have you noticed the same faces again and again with retargeted ads… you might not like the practice, but those faces are probably growing on you.

 5) Authority

The power of authority to elicit compliance is dramatically demonstrated by the Milgram Experiment. If you’re not familiar with it, it’s well worth a read… it’s a fascinating (and quite alarming) illustration of just how compliant people really are in the face of authority. The conclusion is… very.

What does this mean for marketers? 
One of the sources of authority, is expertise. Expertise has power, and if an expert prescribes something as good for you, you are likely to buy it.

So if possible, take on the role of expert (or acquire the endorsement of an expert). If you want to see people practicing this principle, spend a couple of minutes looking around LinkedIn!

In ad text or landing page text, a phrase like ’10 years’ experience’ will help to establish some expertise, as would high-level, industry-related content.

If you’re an individual selling your services, an image of you speaking on stage would be a typical feature of your landing page … designed quickly to establish your credentials as an expert, and an authority.

 6) Scarcity

As we associate higher price with higher quality, a similar automatic association arises with availability. Rare = Valuable, and you’ll see the adjective ‘rare’ often used specifically to imply desirability.


Ads and landing pages often use phrases like: ‘limited-stock’, ‘limited-time offer’ etc.

Exclusive’ / ‘special edition’ are also used to drive desirability, and they work. 

Here’s a good example: 


“In high demand – only 2 left on our site”. Ring the alarm bells..!

While we’re looking at this listing, see how many instances of social proof you can spot…

The ‘risk free’ invitation to book without cost will also play on another one of the techniques we’ve looked at… 

Taking that low-barrier first step now, will activate the ‘Consistency and Commitment’ principles, making the user place a higher value on going all the way with their choice when it comes time to pull out the wallet.



Next time you run an ad test, see if you can weave one or more of these ideas into your new ads… 

They are already well known, but they’re powerful, and the psychological triggers they play on aren’t going away any time soon.



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