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6 Proven Psychological Principles That Convert Browsers Into Buyers


Written by

Phil Coleman


21 MIN

6 Proven Psychological Principles That Convert Browsers Into Buyers

6 Proven Psychological Principles That Convert Browsers Into Buyers

In 1984, Dr. Robert B. Cialdini published a book called Influence: The Psychology of Persuasion. Since then, it has become a must-read for any serious marketer.

The reason for this is simple.

You cannot sell without tapping into human psychology. In fact, how well you do it determines your results. Whatever we’re buying, we all respond to simple psychological ‘triggers’.

Marketers can harness these to boost the persuasion level of their marketing. And this masterpiece contains a gold mine of seriously powerful and proven principles you can harness to boost the results of your marketing.

But it was published 35 years ago. Before online marketing’, I hear you scream.

Don’t worry, these principles are evergreen. They are not based on specific advertising channels, platforms or mediums – they are all based on simple human psychology.

Along with looking at other people’s research, Dr Cialdini spent 3 years “undercover” applying for and training at fundraising organisations, used car dealerships, and telemarketing firms.

Thanks to this, he was able to observe and document persuasion situations as they happened.

His findings showed that influence is based on six key principles:

  1. Reciprocity
  2. Commitment and Consistency
  3. Social Proof
  4. Authority
  5. Liking
  6. Scarcity

Let’s take a closer look at each one, with examples of how you can use them in your marketing.


This principle is based on the fact that by nature we feel the need to return favours and good deeds, and treat others as they treat us.

If you do something for someone with no conditions or expectations, they are more likely to do something for you in return.

Here’s what Dr. Cialdini says about this:

“It’s the principle that suggests that people give back to you the kind of treatment that they’ve received from you. If you do something first, by giving them an item of value, a piece of information, or a positive attitude, it will all come back to you. The key is to go first.

If you smile at a stranger, you get a smile back. If you don’t, you don’t get a smile back. That’s essentially the rule. Whatever it is that you would like to get from a situation, you can increase the likelihood that it will be forthcoming if you provide it first.”

Have you ever received a direct mail piece from an insurance company which included a free pen? That’s harnessing this specific principle.

The free, unexpected gift makes many people want to reciprocate. Even if it’s just giving your offer serious consideration.

It obviously doesn’t work on everyone. However, it works on enough of the population to make a difference to conversions.

How can I use this in my marketing?

Offer free stuff to your potential customers!

Free content, research, or even professional advice, all take advantage of reciprocity. Many people feel beholden to act on your offer, thanks to your gift triggering the law of reciprocation.

Try posting expert tips, how-to guides, latest research, time-saving ideas etc on your website. Your visitors will be grateful for your free help and much more likely to respond favourably to your offers.

You’ll also have the extra benefit of new content for the search engines to index, attracting more potential customers.

A classic example of how this principle is used in digital marketing is to offer free reports, guides, samples, tips, videos, coaching etc, in exchange for a prospect’s email. Ask for an email without offering anything first and your response is usually much lower, as there is no act to reciprocate.

Look at what other people in your industry are doing to come up with ideas. However, try and be original so you stand out from your competitors.

And always test different things, as you never know what will bring you the best results.

A couple holding rings
Marriage – an example of reciprocity and commitment

Commitment and Consistency

As humans, we subconsciously feel the need to behave in a manner consistent with our past behaviour. And once we’ve made a commitment publicly, we’re far more likely to stick to our guns and deliver on it.

Here’s what Dr. Cialdini says about this:

“There’s a great study that I like to cite having to do with one restaurant owner in Chicago who was able to reduce the number of no-shows at his restaurant by just having his receptionist change two words that she used when she took a booking. Previously she said, “Thank you for calling Gordon’s Restaurant. If you have to change or cancel your reservation, please call.” That was the standard approach and it was producing about 30 percent no-shows.

If she changed to saying instead of “Please call if you have to change or cancel your reservation,” if she said, “Will you please call if you have to change or cancel your reservation?” and waited for people to say yes, as they all did, then no-shows dropped to 10 percent because people were going to be consistent with what they had said publicly they would do.”

In a famous study, researchers asked people to erect a Drive Safely advertising board in their garden. Very few people agreed, even though it was to support a Drive Safely campaign.

Meanwhile, in a similar neighbourhood, four times as many agreed. How come?

Simply because ten days previously, these people agreed to place a postcard in their front window supporting the Drive Safely campaign.

In a nutshell, the initial commitment of the postcard led to a 400% increase in those agreeing to the large board, because it was consistent with their past, albeit smaller, commitment.

How can I use this in my marketing?

Instead of going straight for the sale, try getting your visitors to commit to something small and preferably free, such as a video, report, guide or cheat sheet.

The simple act of accepting your free offer increases the chance of those visitors eventually seeing themselves as customers. And this change in self-perception means they’re more likely to be receptive to your follow up offers.

Simply break up larger commitments or actions into smaller micro-commitments. It’s not only less daunting, but it also triggers this principle.

You can also use multi-page forms to exploit this principle. Rather than have a large complex form, split it up. When a visitor fills in a few fields then clicks through, that’s a ‘micro commitment’.

If they are then presented with another page with more fields, the need for consistency drives them to complete it.

Social proof

This is based on the old adage, ‘There’s safety in numbers’. Cialdini defines social proof as simply people doing what they observe other people doing.

This principle is stronger when:

  • We’re unsure what to do
  • Those we observe are similar to us

Here’s what Dr. Cialdini says about this:

“People will be likely to say yes to your request if you give them evidence that people just like them have been saying yes to it, too. For example, I saw a recent study that came from Beijing. If a manager put on the menu of the restaurant, “These are our most popular dishes,” each one immediately became 13 to 20 percent more popular.

What I like about that is, not only did a very small change produce a big effect, it was entirely costless and entirely ethical. It was only the case that these popular items were identified as popular items. That was enough to cause people to want to go along with what they saw as the wisdom of the crowd.”

If a potential customer sees that you’re popular with other people, it can draw them towards you. They feel safer in a group and they are more confident that they’re making the right buying decision.

‘If all these people love them, they must be pretty good.’

How can I use this in my marketing?

There are many ways to harness this principle in your business, and the great thing is, they’re easy to implement.

  • Show off the great reviews and comments about your products from current customers.
  • Got a large number of satisfied customers, members or clients? Tell your prospects!
  • Does your product outsell your competitors? You’re popular. Shout about it.
  • Got celebrity endorsements? Let people know. ‘If Famous McFamous has bought this, it must be good
  • Has your product or business been mentioned in the media? Excellent. This kind of social exposure attracts other people.

You need to promote anything that shows popularity and customer satisfaction. This will help potential customers to trust you, as that many people can’t be wrong about you!


A doctor at a computer
Trust me, I’m a doctor from the 80s!

Have you noticed that we tend to trust and obey authority figures, even the objectionable ones? We simply can’t resist human nature.

Job titles such as ‘Dr’ and anyone in a position of authority or a uniform, immediately gain our respect and make us more likely to accept what they say. This is why so many health products have a doctor in a white coat endorsing them.

‘If a Doctor says it works, it must be ok’. The trust and proof implied when an authoritative figure is promoting the product cannot be underestimated.

In fact, you probably trust this information because the author of the referenced book is a doctor! A perfect example of the principle in action.

So here’s what the trusted doctor says about this:

“Authority refers to the tendency of people to be persuaded in your direction when they see you as having knowledge and credibility on the topic. What’s interesting is how many people fail to properly inform their audience of their genuine credentials before launching into an influence attempt. It’s a big mistake.

A crucial point here with regard to authority is I’m not talking about being in authority and using that lever to move people in your direction. There are all kinds of problems associated with that, including resentment and resistance. I’m talking about being an authority. Someone who is perceived as a credible source of information that people can use to make good choices.”

Authority is one of the most powerful principles on this list.

Psychologist Stanley Milgram’s famous study showed that test subjects were so deferential to the perceived authority of a white lab coat wearing experimenter, they subjected an unseen person with electric shocks!

Don’t worry, the screams were simulated, and nobody was actually hurt in the experiment.

How can I use this in my marketing?

You can add authority to your own brand by showing off awards you’ve won, books you’ve written, guest appearances you’ve made or high-level partnerships you’ve formed.

You can also borrow other people’s authority by hiring a professional to endorse your brand or product. It can be expensive, but the boost it can give to your results can pay off handsomely.

It’s hard to stand out in crowded marketplaces, but these kinds of things really resonate in people, as they raise you above your competitors.


According to Cialdini, how much you can be influenced by someone, depends on how much you like them. He also adds a key element of liking is having things in common with each other.

Here’s what the good Dr. has to say about this:

“No surprise that people prefer to say yes to a request to the degree that they know and like the requester. A simple way to make things happen in your direction is to uncover genuine similarities or parallels that exist between you and the person you want to influence, and then raise them to the surface. That increases rapport.

Similarly, uncovering genuinely admirable or commendable features of a person, and complimenting the person on those things will lead to liking. Simple things that we can easily get access to. Instead of burying them and keeping them under wraps, we mention those similarities, we mention those compliments that are genuine to provide. That establishes a rapport that leads to a yes.”

This is why good salespeople try to establish common ground with their potential customers.

If they can find a shared interest, hobby, sport, education etc, they can use that to build rapport and come across as human and likeable.

‘Hey, I’m the same as you. Buy my stuff!’

How can I use this in my marketing?

The best way to harness this principle is to ensure you show your prospects you’re likeable.

How do you do that? The best place to start is on your about page. It’s the perfect place to show off your human side and to bond with your potential customers.

A 2015 study [PDF] revealed that 52% of visitors visit your about page, after your homepage.

This is a sign that they want to know more about you. If your page has your business details and a few paragraphs of self-praise, you’re going to lose that visitor in a heartbeat.

People do not want to deal with anonymous brands. How can they trust you if you don’t show yourself? Why are you hiding? Aren’t you legit?

You can overcome this by including photos of the founders, the staff (Smiling of course), group activities, workplace events, premises, office dog etc. Think of it like your business profile, where you show off the human side of your business.

The more human you make it, the more the customers you are trying to attract will resonate with you.

Only one more point remaining, read it before it’s gone…

Heart drawn in the sand
Who doesn’t like the beach?


What happens when there’s a shortage of something? More people want it. There’s something about human psychology that makes us hate to miss out. Especially on a bargain.

Our fear acts as a powerful motivator to encourage us to act quickly. That’s why the suggestion of scarcity works so well to boost conversions.

Here’s what Dr. Cialdini says about this:

“People will try to seize those opportunities that you offer them that are rare or scarce, dwindling in availability. That’s an important reminder that we need to differentiate what we have to offer that is different from our rivals or competitors. That way we can tell people honestly, “You can only get this aspect, or this feature, or this combination of advantages by moving in the direction that I’m recommending.”

FOMO (Fear Of Missing Out) has driven many sales over the years, as it’s such a powerful force. The popularity of Black Friday sales, for instance, is staggering.

It is defined as a “pervasive apprehension that others might be having rewarding experiences from which one is absent. It is characterized by the ‘desire to stay continually connected with what others are doing.’”

It seems like if we can’t have something, we want it more. If something is scarce, we’ll pay more for it.

How can I use this in my marketing?

Obviously, we’re not suggesting you lie about availability. But you should announce when you have genuine limited stock.

Any of these will work:

  • Genuinely limited stock
  • Limited time sale
  • Ending a product line and only a few left
  • Limited introductory price
  • Limited free bonuses

And here are some classic uses of this principle:

  • Only 3 left
  • Offer expires at midnight
  • Only 4 seats left at this price
  • Only 2 room left
  • Last ones available
  • Special deal
  • 50% off – today only

Another benefit of this principle is the fact that when you announce low or limited stock, visitors who aren’t quite ready to buy, may feel the need to buy earlier so they don’t miss out. You can read more about this in our guide to psychological pricing.

Finally, please don’t ever fake scarcity. If you overuse it your visitors will see right through you.


All marketing is based on psychology. If you learn how to tap into this in a proven and effective way, you can seriously improve your results.

Dr. Cialdini’s research can be invaluable to your business if you learn to harness it. You may find some of these work better than others for you, so always test everything.

Remember that understanding buying psychology is the key to understanding your prospects. Familiarise yourself with these principles, learn to apply them and you really can improve your results.

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